------ -RE51'RICTED"
---_________-....
AN 16-40SCR624-2
HANDBOOK
MAINTENANCE INSTRUCTIONS
RADIO SET
5CR-624-A AND 5CR-624-B
LATEST REVISED PAGES SUPERSEDE
THE SAME PAGES OF PREVIOUS DATE
Insert revised pages into basic
publication. Destroy superseded pages.
PUBLISHED UNDER AUTHORITY OF THE SECRETARY OF THE AIR FORCE AND
THE CHIEF OF THE BUREAU OF AERONAUTICS
------- RESTRICTED
Air Force·WPAFB-O-18 FEB 52 3,800
---------______
30 JUNE 1945
REVI SED 2 JANUARY 1952
AN 1 6-40SCR62 4 - 2
Reproduction for non-military use of the information or illustrations contained in
this publication is not permitted without specific approval of the issuing service
(BuAer or AMC). The policy for use of Classified Publications is established for
the Air Force in AFR 205-1 and for the Navy in Navy Regulations, Article 1509.
�----.....;..--- LlST OF REVIS E D PAGES ISSUED --------__..
INSERT LATEST REVISED PAGES. DESTROY SUPERSEDED PAGES.
NOTE: The portion of the text affected by the current revision is indicated by a vertical
line in the outer margins of the page.
Page
No.
Dale of Latest
Reflision
i . . ... ,..................27 May 1949
ii ... . ...
. .. . . . 27 May 1949
... . . .27 May 1949
iv .. .. . .
1-1 ......................."..27 May 1949
1-3 ..........................27 May 1949
1-6-2-0 ..................27 May 1949
2-9 ..........................27 May 1949
17 July 1951
4-10
*4-24 ....................2 January 1952
4-25 ........................27 May 1951
4-26-5-0 ................27 May 1951
*5-28 ....................2 January 1952
*5-29 ....................2 January 1952
*7·29 ....................2 January 1952
*7-30 ....................2 January 1952
*7-31 ....................2 January 1952
*7-32 ....................2 January 1952
7-37 ........................27 May 1951
7-38 ........................27 May 1951
*8-5-:-8-6 ............2 January 1952
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*The asterisk indicates pages revised, added or deleted by the current revision.
ADDITIONAL COPIES OF THIS PUBLICATION MAY BE OBTAINED AS FOLLOWS:
A
USAF ACTIVITIES.-In accordance with Technical Order No. 00-5-2.
NA VY ACTIYITIES.-Submit request to nearest supply point listed below, using form NavAer 140:
NAS, Alameda, Calif.; ASD, Orote, Guam; NAS, Jacksonville, Fla.; NAS, Norfolk, Va.; NASD, Oahu;
NASD, Philadelphia, Pa.; NAS, San Diego, Calif.; NAS, Seattle, Wash.
For listing of available material and details of distribution see Naval Aeronautics Publication I ndex
NavAer 00-500.
USAF
Revised 2 January 1 95 2
AN 16-405CR624-2
TaBLE OF CONTENTS
Page
Sect;01l
Destruction of Abandoned Material in the Combat
Zone .........................................:............................... V
Unsatisfactory Report ................................................ V
I . G ENERAL DESCRIPTION ................. 1-1-1-6
1. General
1-1
2. Equipment Supplied .............................. 1 - 1
3. Equipment Required But Not Supplied 1-4
4. Description of Principal Assemblies .... 1-4
a. General .............................................. 1-4
b. Transmitter-Receiver Assembly........ 1-4
c. Rectifier RA-62-B or RA-62-c.......... 1-5
d. Antenna AN-94-A, AN-94-B, or
AN-94-C and Cord CD-950-A...... 1-5
e. Antenna AN- 1 88 and Cord
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .
CD-1333 ........................................... 1-5
f. A ntenn a Mast MA-7-A.................... 1-6
BC-1175-A, BC1171-A, BC- 1 1 76-A, BC-1312,
BC- 1 313, and BC-1314.................. 1-6
g. Control Boxes
I
h.
n.
Loudspeaker LS-IO-A, LS-IO-B
and LS-IO-C... . . . ........ . ....
Section
Page
4. Defense Against Jamming . .... . .
. 3-1
a. General .............................................. 3-1
b. Procedure .......................................... 3- 1
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5. Disassembly After Operation.. .
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Revised 27 May 1 949
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b. Oscillator ..........................................
c. First Harmonic Amplifier................
d. Second Harmonic Amplifier.... . . .
e. Power Amplifier . ..
. ............... ...
f. Speech Amplifier ..............................
g. Modulator ........................................
h. Meter Shunt Circuits...... ...............
3. Radio Receiver BC-624-A or
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BC-624-AM ............................. ..........
General ..............................................
R-F Amplifier .... . . .. . ... . ... . .
Crystal Oscillator .. . . . ..... . ... . ...
Harmonic Generator . . . . . . . .
Harmonic Amplifier . . . . . .. ....
Mixer .. .... .. . . ... .
.. . .
First, Second, and Third I-F. . . ...
h. Detector and AVC Circuits in
Radio Receiver BC-624-A..............
i. Detector, Noise Limiter, AVC
a.
b.
c.
d.
e.
f.
g.
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Delay Circuits in Radio
Receiver BC-624-AM......................
j. First A udi o- Frequency Amplifier....
k. Second Au dio- F requ en cy Amplifier
1. Audio Squelch ..................................
Radio Receiver BC-624-C......................
a . General ... ...
............................
b. Detector and A Ve ...........................
c. Noise Limiter .... .... ..... . . .. . . ....
d. Squelch .............................................
e. Second and Third Audio Stages
Rack FT-244-A ......................................
Rectifier RA-62-B and RA-62-C............
a. General
.. .. . . . .. . . . .
b. A-C Input . . . ......................................
c. D-C Heater Voltage Output..... .......
d. D-C Bias V olta ge Output.......... .....
e. D-C Plate Voltage Output.......... .....
Control Boxes ........................................
a. General .............................................
b . Control Bo x BC- 1I75-A....................
c. Contro l Box BC-lI71-A.............. .....
d. Co ntrol Box BC- 1 1 76-A (Remote) ..
e. Control Box BC-1312 ........................
f. Co ntrol Box BC-1314........................
g. Control Box BC-131 3................ . . .. .
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. . . .3-0-3-1
1. Starting and Stopping the Equipment.. 3-0
2. Normal Operation ................................ 3-0
(Used with Radio Set SCR- 624-A )
a. Using Control Box BC-1175-A ....... 3-0
b. Using Control Box BC- 1 312 ........... 3-0
(Used with Radio Set SCR-624-B )
c. Using Control Box BC-l171-A........ 3-0
d. Using Control Box BC-1314............ 3-0
e. Using Control Box BC-1176-A
(Remote)
. ... ... . .. . . . .. ..
3-1
f. Using Control Box BC-I313............ 3-1
3. Land-Line (Telephone) Communication .................................................. 3-1
Ill. OPERATION
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1. General ........................................... ....... 4-1
2. Radio Transmitters BC-625-A or
BC-625-AM ..................... ; .................. 4-2
a. Gene ral . . ....................................... 4-2
.
. . . .
.
IV. THEORY OF OPERATION............... .4- 1-4-26
1-6
SCR-624-A ...................................... 2-0
2. Install �tion ............................................ 2-4
a. Choice of Site.................................... 2-4
b. A r rangement of Equipment on Site 2-4
c. Assembly of Antenna Mast MA-7-A 2-5
d. Adjustment of A ntenna AN-94-A,
AN-94-B, or AN-94-C.................... 2-8
e . Assembly of Antenna AN-188........ 2-8
f. Erection of Antenna M ast MA-7-A 2-8
g. Interconnection of Assemblies ....... 2-9
3. Adjustments . ..... . . . ..
. . . . ;. 2-9
4. After-Installation Tests ......................... 2-9
.
.
. . .. . . . . . . . .. . . .2- 0-2-11
1. Pre-Transpo rtation Check .................... 2 -0
a. Equipment Check ............................ 2-0
b. Check of Power Unit PE-75-D........ 2-0
c. Bench Check for Radio Set
INSTALLATION AND ADJUST-
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5.
6.
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4-2
4-2
4-2
4-6
4-6
4-6
4-6
4-6
4-6
4-10
4-10
4-10
.4-10
4-10
4- 1 1
4- 1 1
4- 1 1
4-13
4- 1 3
4- 1 3
4- 13
4-13
4- 13
4-13
4- 16
4-20
4-2 1
4-2 1
4-2 1
4-23
4-23
4-23
4-23
4-23
4-23
4-23
4-24
4-24
4-24
4-24
4-24
AN 16-405CR62.4-2
IABLE OF COIlTEIITS-Contl..uecl
Page
Sect;(J1I
6.
a. Frequency Changing Operation........ 4-24
b. Transmit Operation ........................ 4-26
9. Loudspeaker LS·lO·A, LS·lO·B
I
.
...
..
b. Cleaning and Lubrication................ 5-34
4-26
c.
MAINTENANCE ...................... ............ 5-0-5-54
7.
1. Daily Inspection .................................... 5-0
b. Operational Inspection .................... 5-0
Adjustment and Reassembly ............ 5-35
Over-all Performance Tests for
.a.
a. Visual Inspection .............................. 5-0
Receiver· Transmitter Assembly.......... 5-39
General .............................................. 5-39
b. Standard Test Conditions................ 5-39
c. Methods of Measurement.................. 5-40
2. Weekey Inspection ................................ 5-0
8. Over·alI Performance Tests (Radio
a. Inspection of Antenna Mast
Receiver BC-624·AM or BC-624-C) .. 5-42
MA-7-A ........................................ 5-0
b. Inspection of Control Boxes
a. Methods of Measurement.................. 5-42
b. Selectivity .......................................... 5-42
BC-ll75-A, BC-ll7l-A,
BC-1I76-A, BC-1312, BC-1314,
c. Receiver A-F Power.......................... 5-42
c. Inspection of Rack FT-244-A.......... 5-1
e. Inputs for Standard Output.............. 5-42
and BC-1313 ............................ ..... 5-0
d.
Noise Suppressor .............................. 5-42
d. Inspection of the Receiver................ 5-2
9. Alignment of Radio Set SCR-624-A
f. Transmitter and Receiver Tuning.... 5-3
a. Transmitter Tuning Using Test
or Radio Set SCR-624-B.................... 5-42
e. Inspection of the Transmitter.......... 5-2
Equipment IE-19-(*)t ................. 5-42
3. Trouble Location .................................. 5-3
b. Transmitter Tuning Using Test
a. Transmitter-Receiver Assembly ...... 5-3
b. Radio Receiver BC-624-A, BC-624c.
c.
AM, or BC-624-c.......................... 5-3
BC-625-AM
d. Receiver Tuning Using Test
.................................. 5-4
Equipment IE-19-(*) .................... 5-49
e. Control Boxes BC-1175-A, BC-1312,
e.-Receiver Tuning Using Test Equip­
ment IE-36 and a Suitable
BC-lI7l·A, BC-U14, BC-1I76-A,
Headset .............. : ........................... 5-52
or BC-1313 .................................... 5-5
4. Trouble Shooting-Detailed ................ 5-5
a. Transmitter Tube Socket Voltage
Measurements .............................. 5-5
b. Receiver Tube Socket Voltage
Measurements .............................. 5-5
c.
Transmitter Continuity and Resist-
f. Testing Remote (Press·to-Talk)
Operation Using Test Equipment
IE-36 .............................................. 5-53
VI. SUPPLEMENT ARY DATA . ...............6-0-6-9
1. Characteristics of Radio Set SCR-624-A 6-0
a. Frequency Range ........................ ..... 6-0
b. Power Supply .................................... 6-0
ance Measurements ................ ..... 5-9
d.
e.
c. Input Current Requirements...... ..... 6-0
Receiver Continuity and Resistance
Measurements ........................ ..... 5-16
d.' Type
f. Beat Frequency Oscillator.......... ..... 6-0
g. Crystal Filter .............................. ..... 6-0
f. Rectifier Continuity and Resistance
Measurements ........................ ..... 5-27
2. Types of Radio Jamming ...................... 6-0
h. Squelch Circuit Characteristics........ 6-0
g. Continuity and Resistance Measure­
for
Control
Boxes
of Modulation.................... ..... 6-0
e. Method of Modulation................ ..... 6-0
Rack Continuity and Resistance
Measurements .............................. 5-24
ments
Equipment IE-36 .......................... 5-45
Receiver I-F Amplier Transformer Alignment ....................... 5-47
Radio Transmitter BC-625-A or
d. Rectifier RA-62-B or RA-62-C........ 5-4
3. Tube Complement .......................... ..... 6-0
BC·
5. Differences Between Radio Receivers
Il75-A, BC-1312, BC-1314, and
4. Supplementary Parts List...................... 6-1
5. Replacement of Vacuum Tubes and
6. Crystal Frequency Chart........................ 6-5
BC-1313
a.
Fuses
........................................ 5-27
. .. . . . . . . .... . ... . . . .. .. . . . .. .. . . . . .. . . . .
. .. . . . . . .
5-32
Replacement of Transmitter
Vacuum Tubes .............................. 5-32
b. Replacement of Receiver Vacuum
Tubes .............................................. 5-33
ii
Replacement ot Rectifier Tubes . ..
d. Replacement of Rectifier Fuses .. ......
-
and LS·IO·C . . . . . . . . . . . . . . . . . . . .
V.
'-33
5-33
Special Maintenance Procedures........... 5-33
a. Disassembly
...................................... 5 3 3
c.
8. Control Circuit ............ , ......................... 4-24
Page
BC-624-A and BC-624-AM ........ ..... 6-4
VII.
TABLE OF REPLACEABLE PARTS ... 7-D-7-36
VIII. DRAWINGS ......................8-1-8-3- 8-4-8-58-6-8-7-8-8-8-9-8-10-8-11-8-128-13 -8-14-8-15-8-16-8-17-8-18
Revi sed 27 May 1 949
AN 1 6-405 C R 624-2
LIST OF TABLES
Page
Tables
1-1.
Equipment Supplied with Radio Set
2-1.
Adjustment of Antennas AN-94-A,
SCR-624-A or SCR-624-B ........................ 1-1
AN-94-B, or AN-94-C for Optimum
Efficiency ..................................................... 2-8
5-1.
Trouble Location Chart for Radio Set
SCR-624
.................................................... 5-3
5-2.
Trouble Location Chart for the Radio
Receiver BC-624 ...................................... 5-4
5-3.
Transmitter Tube Socket Voltage Meas·
5-4A.
Radio Receiver BC-624-A, BC-624-AM­
5-7.
Rack Continuity and Resistance Measure·
5-8.
Rectifier Continuity and Resistance Meas·
ments
5-9.
Continuity and Resistance Measurements
5-10.
Continuity and Resistance Measurements
Receiver
BC-624-C-Tube
Socket
Voltage Measurements .............................. 5-7
5-5.
Transmitter Continuity and Resistance
Measurements .......................................... 5-9
5-6A.
Radio Receiver BC-624-A or BC-624-AM­
for Control Box BC-1312........................ 5-29
5-11.
Continuity and Resistance Measurements
for Control Box BC-1314.......................... 5-29
5-12.
Continuity and Resistance Measurements
for Control Box BC-1313........................... 5-32
5-13.
Cleaning Chart ............................................ 5-35
5-14.
Lubrication Chart ........................................ 5-35
6-1.
Supplementary Parts List for Radio Re·
ceiver BC-624-C ........................................ 6-1
Continuity and Resistance Measure·
ments ......................................................... 5-16
5-6B.
5-24
for Control Box BC-1175-A.................... 5-27
Tube Socket Voltage Measurements........ 5-7
Radio
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . .
urements .................................................... 5-27'
urements ....... ...................... ........................ 5-5
5-4B.
Page
Tables
6-2.
624-A and BC-624-AM............................ 6-4
Radio Receiver BC-624.C-Continuity and
Resistance Measurements ..................'...... 5-19
-------
Differencc:.s Between Radio Receivers BC·
6-3.
Crystal Frequency Chart......................... , ..... 6-5
* -------
LIST OF ILLUSTRATIONS
Page
F;g�e
1-1.
Radio Sets SCR-624-A and SCR-624-B-
4-2.
Radio Transmitters BC-625-A and
4-3.
Radio Transmitters BC-625-A and
4-4.
Radio Transmitters BC-625-A and
4-5.
Radio Transmitters BC-625-A and
Major Assemblies .................................... 1-0
2-1.
2-2.
2-3.
Transmitter·Receiver
Assembly - Covers
BC-625-AM-Front View ........................ 4-3
Open, Top View .................................... .... 2-2
Antenna Mast MA· 7-A-Components......... 2-3
Antenna
Mast
MA-7-A-Location
BC-625-AM-Rear View ........................ 4-4
BC-625-AM-Bottom Oblique View...... 4-4
and
Assembly Size .................................... ..... 2·4
Page
Figure
2-4A.
Antenna Mast MA· 7-A-Assembly Details 2-5
BC-625-AM-Showing Locking Type
2�4B.
Antenna AN-188-Assembled ............. " ..... 2-5
Antenna Coupling ..................................... 4-5
2-5.
Antenna Mast MA· 7-A-Assembled.......... 2-6
2-6.
Antenna Mast MA-7-A-Erected ................ 2-7
2-7.
Radio Set SCR-624-A-Installation..... " ..... 2-10
2-8.
Radio Set SCR-624-B-Installation ............ 2-11
4-1.
4-6.
BC-625-AM-ShowiJ:ig
Non.Locking
Type Antenna Coupling......,.................... 4-5
4-7.
Radio Receivers BC-624-A and
BC-624.AM-Top View .......................... 4-7
Radio Transmitter BC-625-A and
BC-625-AM-Top View ........................ 4-2
Radio Transmitters BC-625-A and
4-8.
Radio Receiver BC.624.C-Top View.." ..... 4-7
iii
AN 1 6-40SCR624-2
Page
Figure
4,9.
4-10.
4-11.
4-12.
4-13.
4-14.
4-15.
4-17.
4-18.
4-19.
4-20.
I
4-21.
4-22.
4-2').
4-24.
5-1.
5-2.
5-3.
5-4A.
5-4B.
..
5-10.
Rectifiers RA-62-B and RA-62-CTransformer Terminal Layout. .. . . ...
Control Box BC-1l75-A-Wiring
Diagram ....................................................
Control Box BC-1312-Wiring
Diagram ......................... .........................
Control Box BC-ll71-A-Wiring
Diagram ....................................................
Control Box BC-1176-A-( Remote)
Wiring Diagram ......................................
Control Box BC-1314-Wiring Diagram....
5-11.
Control Box BC-1313-Wiring Diagram.... 5-3 1
5-12.
Rack Mechanism and Ratchet Motor........ 5-37
AWS Color Code-Fixed Moulde a Paper
Dielectric Capacitors .............................. 6-7
5-5.
Radio Receivers BC-624-i\ and
BC-624-AM-Rear View ........................ 4-8
Radio Receiver BC-624-C-Rear View....... 4-9
and BC-624-C-Right Side View.......... 4-12
Radio Receivers BC-624-A, BC-624-AM
Radio Receivers BC-624-A, BC-624-AM..
and BC-624-C-Front View................... 4-14
Radio Receivers BC-624-A, BC-tl24-AM
and BC-624-C-Front Oblique View...... 4-14
R-F Oscillator Assembly ............................ 4-15
Radio Receiver BC-624-AM-Simplified
Schematic of AVC and Noise Suppressor
4-16
Radio Receiver BC-624-A-Rewiring of
the Squelch Circuit .................................. 4-17
Simplifi-ed Diagram of the Transmitter­
Receiver Microphone Mixing Circuit.... 4-17
Receiver R-F and Oscillator AssemblyWiring Diagram .................................... 4-18
Receiver I-F Transformers--Wiring
Diagram .................................................... 4-19
Rack FT-244-A-Center Cover RemovedTop View .......................................... ..... 4-20
Rack FT-244-A-Wiring Diagram............ 4-22
Loudspeaker LS-lO-A-Circuit Diagram .... 4-25
Loudspeaker LS-lO-B--Circuit Diagram.... 4-25
Loudspeaker LS-lO-C-Circuit Diagram . 4-25
Transmitter-Receiver Assembly-Front
Oblique View .......................................... 5-1
Transmitter Tube Socket Layout and
Voltages ....... ................. .......................... 5-6
Radio Receiver BC-624-A or BC-624-AM
Tube Socket Layout and Voltages........ 5-10
Radio Receiver BC-624-A-Continuity Test
Diagram .............................................. ..... 5-14
Radio Receiver BC-624-C-Location of
Components Terminals and Terminal
Boards ................ .................................. ..... 5-20
.
5-6.
5-7 .
..
5-8.
5-9.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . .
4-16.
Page
Figure
6-1.
.
...
.
...
5-2 5
5-26
5-28
5-30
5-30
5-31
6-2.
AWS Color Code-Fixed Mica Dielectric
Capacitors .................................................. 6-8
6-3.
AWS Color Code-Fixed Ceramic D ielectric Capacitors .......................................... 6-9
8-1.
Radio Se� SCR-624-A-Complete Sche. Diagram ................................... 8-3-8-4
matic
8 -2.
Radio Set SCR-624-B--Control Network,
Schematic Diagram ...........................8-5-8-6
8-3.
Radio Receiver BC-624-C-Schematic
Diagram .............................................8-7-8-8
8-4.
Radio Transmitter BC-625-AM- Schematic Diagram ................................. 8-9-8-10
Radio Transmitter BC-625-A-Wiring
Diagram .......................................... 8 -11-8-12
8-5.
8-6.
Radio Receiver BC-624-A-Wiring
Diagram ........................................... 8-13-8-14
8-7.
Radio Receiver BC-624-AM-Wiring
Diagram ............................................8-15-8-16
8-8.
Radio Receiver BC-624-C-Wiring
Diagram ...........................................8-17-8-18
*
SAFETY NOTICE
This equipment employs .high voltages which are dangerous and may be fatal if
contacted by personnel. Use extreme caution when working with this equipment.
iv
Revised 27 May 1 949
AN 1 6-40S CR624-2
R ES T R I CTED
Z)� tJf
/I� 7Itate'Zid
Ue
de
� '1fN1e
In case it should become necessary to prevent the capture of this equipment and when ordered to do
so,
DESTROY IT SO TIlAT NO PART OF IT CAN BE SALVAGED, RECOGNIZED OR USED BY THE
ENEMY.
BURN ALL PAPERS AND BOOKS.
Means:1. Explosives, when provided.
3. Burning by means of incendiaries such as gasoline, oil, paper, or wood.
2. Hammers, axes, sledges, machetes, or whatever heavy object is readily available.
4. Grenades and shots from available arms.
5. Burying all debris or disposing of it in streams or other bodies of water, where possible and
when time permits.
Procedure:1.
2.
3.
4.
5.
7.
6.
8.
Obliterate all identifying marks. Destroy nameplates and circuit labels.
Demolish all panels, castings, switch- and instrument-boards.
Destroy all controls, switches, relays, connections, and meters.
Rip out all wiring and cut interconnections of electrical equipment. Smash gas, oil, and watercooling systems in gas-engine generators, etc.
Smash every electrical or mechanical part, whether rotating, moving, or fixed.
Break up all operating instruments such as keys, phones, microphones, etc.
Destroy all classes of carrying cases, straps, containers, etc.
Bury or scatter all debris.
DESTROY EVERYTHING!
*
For U. S. Army Air Force Personnel:
.
In the event of malfunctioning, unsatisfactory design, or unsatisfactory installation of any of the compo­
nent units of this equipment, or if the material contained in this book is considered inadequate or erroneous,
an Unsatisfactory Report, AAF Form No. 54, or a report in similar form, shall be submitted in accordance
with the provisions of , Army Air Force Regulation No. 1 5-54 listing :
1. Station and organization.
2. Nameplate data (type number or complete nomenclature if nameplate is not
attached to the equipment) .
3. Date and nature of failure.
4. Radio model and serial number.
5. Remedy used or proposed to prevent recurrence.
6. Handbook errors or inadequacies, if applicable.
For U. S. Navy Pers,onnel:
Report of failure of any part of this equipment during its guaranteed life shall be made on Form N. Aer.
41 12, "Report of Unsatisfactory or Defective Material," or a report in similar form, and forwarded in accord­
ance with the latest instructions of the Bureau of Aeronautics. In addition to other distribution required, one
copy shall be furnished to the inspector of Naval Materiel (location to be specified) and the Bureau of Ships.
Such reports of failure shall include :
1. Reporting activity.
2. Nameplate data.
3. Date placed in service.
4. Part which failed.
5. Nature and cause of failure.
6. Replacement needed (yes-no) .
7. Remedy used or proposed to prevent recurrence.
For British Personnel:
Form 1022 procedure shall be used when reporting failure of radio equipment.
R ESTRI CTED
v
Section I
Figure 1-1
RESTRICTED
AN 16-40SCR624-2
HEeT/P!ER
Rt\-62-B
mAP CRATE (ANTENNA
f i g u re J - J.
1-0
MA-7A)
R a d io Sels SCR-624-A and SCR-624-B-Ma;or Assemblies
RESTRICTED
Section I
Paragra phs 1 -2
AN 1 6- 40SCR 624-2
SPECIAL
NOTICE
All material in this handbook applies to both
Radio Set SCR-624-A and SCR-624-B except as
otherwis� designated. All similar units are me­
chanically interchangeable.
SECTION I
GENERAL DESCRIPTION
1.
GENE RAL.
a. Radio Set SCR-624-A is a complete radio ground
station consisting of a transmitter and receiver designed
for communications work at very high frequencies. It
is especially constructed for transportation by air.
b. Radio Set SCR-624-A may be operated on anyone
of four crystal-controlled channels within 100 to 156
megacycles. Control facilities are provided so that the
transmitter and receiver may be operated at the station,
at a remote distance of 500 feet from the station, or at
a remote distance up to two miles. Channel selection
can be made at the station or at the 500-foot remote
2.
c. The normal carrier power of this equipment is 6
to 8 watts at a frequency of 100 to 156 megacycles.
A-C power requirements are 40 to 60-cycle, single
phase, 100 to 130 volts or 200 to 260 volts, supplied
by an a-c power line or by an auxiliary power unit.
The power source must be able to furnish 325 watts at
11 5 volts or 320 watts at 230 volts.
EQU I PMENT SUPPLIED.
(See Table 1-1.)
TABLE
pn
l -1-EQU I PMENT SUPPLIED WITH RADIO SET SCR-624-A OR SCR-624-B
Qua"t;ty
Equipment
,1
2
I
points of control, while only send-receive communica­
tion is possible at the two-mile remote point. Land
line telephone control is possible between any two
points of control by use of Telephone EE-8-A or EE·8-B.
(See fig. 2-7 for installation.)
1
2
2
Army Type
Designation
Name of Unit
( 1 ) RADIO SET SCR·624·A
Chest Including:
Control Box
Control Box
Control Box
Telephone
Tool roll
Cord
Cord
Cord
Loudspeaker
Chest Sets
Headsets
Transmitter·Receiver As·
sembly, consisting of:
Radio Transmitter
Radio Receiver
Spare Tubes Box, containing:
Revised 27 May 1949
Navy Type
Designation
-
LS·lO·A, LS·lO-B,
TD·2
HS·33
Dimensions
34" x 16%" x 13%"
7'4"x4%"x4%"
6%"x3%"x3%"
6·5 /6" x 2t;;." x 2%"
CH· 1 7 3·A
BC· 1l75-A
BC-ll71-A
BC- 1l76·A
EE·8·A
CD·875·A
CD 80 9·A
CD-951·A
·O.'er·ali
or
LS·10·(;
Ihs.
Weight
134
Numerical
Series of
Reference
Nt).
200
200
200
6" long
6" long
6" long
16a\" x 12�&"
x
BC·625·A
or
BC·625·AM
BC·624·A
or
BC·624·AM
or
BC-624·C
lOti"
49
100
200
12%" x9" x 3"
1-1
Section I
P a ra g ra p h 2-Ta b l e l-l-ICon'tl
AN 1 6-40S C R 6 2 4 - 2
T A B L E I-I-EQU I PMENT S U P P L I E D WITH RADIO SET SCR-624 -A O R SCR-624 - B (Con't) .
Quantity
per
Equipment
3
2
1
2
1
·3
2
10
I
4
1
4
4
1
4
4
1
2
22
4
1
4
4
8
4
2
2
2
1
2
2
1
8
1 -2
Name of Unit
Tube
Tube
Tube
Tube
Tube
Tube
Tube
Tube
Tube
Chest, including:
Rectifier
Army Type
Designatiotl
JAN-S32 (VT- l lS)
JAN- 1 2 A6 (VT- 134)
JAN- 1 2J 5 (VT- 1 3 5 )
JAN- 12CS (VT- 169)
JAN-6G6G (VT- 19S)
JAN-6SS7 (VT- 199)
JAN-9002 (VT-202 )
JAN- 12AH7GT (VT-207)
JAN- 12SG7 (VT-209)
CH- l 72-A
RA-62-B or
RA-62-C
Spare Parts Box containing:
JAN-6X5GT (VT- 126-B)
Tube
JAN-5U4G (VT-244)
Tube
FU- 50
Fuse
Cord
CD-SIO-A
Cord, with reel
Crank
Chest including:
CH- 1 70-A
AN-94-A or
Antenna
AN-94-B or
AN-94-C
Cord
C D-950-A
Mast Strap Crate, including:
Antenna Mast MA-7-A,
consisting of:
Mast sections
Mast section
Coupling sleeve
assemblies
Digging bar
Anchors (screw)
Anchors (straight)
Stays Box, including:
Stays, bottom (orange)
Stays, top (black)
Radius rope (black)
Guy ropes (boom vang)
Block and tackle assembly
Shackles
Shackles
Base plate assembly
Boom and assembly
Sledge
Ring and chain
Stakes
Mast end clamp assembly
Clamps (coaxial cable)
Wrenches (T socket)
Wrenches (end)
Wrenches (spintite)
Wrenches (spindte)
Spare Parts Box, includes:
Shackles
Shackles
Rope
Clamps (coaxial cable)
Coupling sleeve assembly
(plain)
Ot'er-all
Navy Type
Designatiolz
JAN-S32
JAN- 12A6
JAN- 12J5
JAN- 12C8
JAN-6G6G
JAN-6SS7
jAN-9002
JAN- 1 2 AH7GT
JAN- 12SG7
DilllenS;QllS
34" x 16%" x 1 3%"
16" x 1 1 i'/' x 10'}�
If
Weight
Ibs.
205
75
JAN-6X5GT
JAN-5U4G
25'
(a-c line)
500'
41
201//' long
75' long
1 1 " x 16'1.," x 12"
152
10' 10"
4' 8"
23" x 13Y/' x 1 1 "
12 1
11"
1';"
7
T� "
27" x 1 3\1:,' x 1 1 "
1/
::! "
4"
Numerical
Series of
Referellc,
No.
45
100
Section I
Para gra ph 2-Table 1 - 1 -ICo n'"
AN 16-40SCR624-2
Coupling sleeve assembly
(1) R ADIO SET SCR-614-B
4"
(with eyebolts)
Chest, including:
BC-I3L�
Control Box
BC-1314
Control Box
BC-1313
Telephone
1
.,
Cord
CD-S75-A
Cord
CD-S09-A
Cord
CD-95 1-A
TD-2
HS-33
Chest sets
2
6' long
CD-1I91
Loudspeaker
2
6' long
6' long
6" lo ng
LS-ID-A, LS-ID-B, or
LS-l0-C
Cord
1
200
200
200
EE-S-A or
EE:S-B
2
ISS
6%"x 3%" x 3%"
6%" x 2 V.' x 2%"
Tool roll
1
I
34" x 160/,' x 15%"
7',1," x4'/g" x 4:%"
CH-IB-B
Control Box
Headsets
Receiver-Transmitter As­
sembly consisting of:
Radio
Tr ansmit ter
Radio
Receiver
BC -6 2 5 - A M
BC-625-A or
100
260
BC-624-A or
BC-624-AM or
BC-624-C
1
Spare Tubes Box, containing:
Tube
Tube
Tube
Tube
Tube
Tube
Tube
Tube
Tube
Tube
Tube
3
3
I
3
2
I
Antenna
Cord
Chest, including:
Rectifier
Spare Parts Box, includes:
2
10
Tube
Tube
Fuse
I
Cord .(with reel)
Cord
JAN- 12A6 (VT: 1 34)
JAN- 12J5 (VT- 135)
)
JAN- 12H6 (VT
JAN-i2CS (VT- 169)
JAN-6G6G (VT- 19S-A )
JAN-6SS7 (VT- 199)
JAN-9002 (VT-202)
JAN-9003 (VT-203)
JAN- 12AH7GT (VT-207)
JAN- 12SG7 (VT-209)
JAN-S32A (VT-lIS)
AN-94-A or
AN-94-B or
AN-94-C or
AN-ISS*
CD-9S0-A or
CD- 1333*
CH-I72-B
RA-62-B or
RA-62-C
JAN- 12A6
JAN- 12J5
JAN- 12H6
JAN- 12CS
JAN-6G6G
JAN-6SS7
JAN-9002
JAN-9003
JAN-12AH7GT
JAN- 12SG7
JAN-S32A
JAN-6X5GT (VT- 126-B)
JAN-5U4G (VT-244)
FU- SO
CD-IIlO-A
JAN-6X5GT
JAN-SU4G
11'%" x 9" x 3"
75' long
7<;' long
34" x 16%"
x
15'%"
16" x 1112" x 10%"
205
75
100
'100' long
25'
Crank
1 1 " x 16%" x 12"
Mast Strap Crate, including:
1'52
Antenna Mast MA-7-A,
consisting of:
S
Mast sections
I
Mast section
4
I
4
4
*
Coupling sleeve
10' 10"
4 ' s"
assemblies
Digging bar
Anchors (screw)
Anchors
(straight)
Sup pli ed with later models of Radio Se t SCR-624-B.
Revised 2'7 May 1 949
1 -3
Section I
Para gra phs 3-4 a -4b(2 )(b l
TABLE
Quantity
per
Equipmmt
1
4
4
l-1-EQUI PMENT SUPPLIED WITH RADIO S E T SCR-624-A oR. SCR·624·B (Con't).
Name 0/ Unit
A,.,ny Type
Designation
6
4
1
4
4
4
2
2
2
2
2
5 "
Tt1
\
Note
Chest CH-170-A has been
eliminated in Radio
its contents have been
CH-173-B.
Set SCR-624-B and
b. TRANSMITTER-RECEIVER ASSEMBLY.-This
assembly i s comprised of Radio Transmitter BC-625-A
(See figs. 2-1 and 5-1.) When prop­
BC-625-AM, and Radio Receiver BC-624-A, BC-624-
AM
or
erly
interconnected to the other components,
1-4
BC-624-C.
Numerical
Series of
Reference
No.
12 1
45
4"
GENERAL.
( 1 ) RADIO SET SCR-624-A-The assemblies of
Radio Set SCR-624-A are contained in three chests, two
boxes, and one crate, namely: Chest CH-l72-A, CH1 73-A, and CH-170-A, the mast stays and the mast spare
parts boxes, and the mast strap crate. (See fig. 1-1.)
Their total weight is 7 1 1 pounds.
(2) RADIO SE T SCR-624-B.-The assemblies of
Radio Set S.CR-624-B are contained in two chests, two
boxes, and one crate, namely: Chest CH-l72-B and CH173-B the mast stays and the mast spare parts boxes and
the mast strap case. Their t otal weight is 669 pounds.
or
Weight
lb..
4"
DESCRI PTION OF MAJOR ASSEMBLIES.
placed in Chest
DimensiOlls
27" x 13%" x 1 1"
EQU I PMENT REQU I R E D BUT N OT SUPPLIED.
a.
Ol}e"�all
11"
IT;
tt"
TIf
11"
/2
5 "
16
·
One Power Unit PE-75-D, an auxiliary a-c power
supply, is required when no a-c power line is available.
This unit is not supplied with the radio set, however.
4.
Navy Type
Designalioll
23" x 13'1/' xlI"
Stays Box, including:
Stays, bottom (orange)
Stays, top (black)
Radius rope
Guy ropes (boom vang)
Block and tackle
assembly
Shackles
Shackles
Base plate assembly
Boom end assembly
Sledge
Ring and Chain
Stakes
Mast and clamp
assembly
Wrenches (T socket)
Wrenches (end)
Wrenches (spintite)
Wrenches (spintite)
Spare Parts Box, includes:
Shackles
Shackles
Coupling sleeve
assembly (plain)
Coupling sleeve
assembly (with eyebolts)
2
3.
AN 1 6-40S C R 6 2 4 - 2
this as-
sembly provides transmission or reception of voice, am­
plitude-modulated signals on any one of four crystal­
controlled frequencies within the range 1 00 to 156
megacycles. The description of each part follows:
(1) CASE CS-BO-A OR CS-BO-C.
(a) Case CS-BO-A is the metal housing provided
for the assembly of the radio transmitter, the radio reo
ceiver and Rack FT-244-A. The case is equipped with 4
shockmounts and a ground strap, and is located in the
right-hand compartment of Chest CH-l73-A (or in the
left-hand compartment in Chest CH- 1 73-B . )
(b) Case CS-BO-C is similar t o Case CS-BO-A ex­
cept that it is equipped with a metal plate bolted to the
shockmounts to provide for installation of Mounting
FT-4BB.
(2) RACK FT -244 - A.-R A CK FT-244-A (see fig.
4-2.0) is a shallow tray which contains interconnecting
wires for the receiver and transmitter, pl ug sockets for
th e attachment of cables from other components of the
equipment, th e ante nn a changeov er re lay, the channel­
control motor and associated mecha nisms , etc. The rack
also serves as a mounting base for the transmitter and
connections between the rack
or receiver are m ad e . through plugs .
and sockets mounted in these un its.
( b) Eight red-painted long-shank screws are
receiver. (See fig. 4-20.)
and the t ran sm itt er
(a) All electrical
\,
AN 1 6- 40S C R 62 4 - 2
employed to hold the transmitter and receiver units
firmly in place.
( c) Recessed handles at each end of the center
channel are provided to facilitate removal of the rack,
receiver, and transmitter from Case CS-SO-A or CS-SO-c.
(d) The rack (see fig. 4-20)-isptovided with
covers attached by means of a slot-and-screw arrange­
ment which makes it possible to slide them away from
ovu the controls of the transmitter and receiver and to
let them drop alongside the front ( transmitter side)
and rear ( receiver side) of the case.
( 3 ) RADIO TRANSMITTER.-The transmitter
occupies half of Case CS-so-A or CS-SO-c. The top
(see fig. 2-1) is equipped with four tuning controls,
a receptacle for the doc meter cord, and a "METER
SWITCH." The antenna-coupling control (see fig. 2-1)
is located on the right side of the transmitter p anel,
and the "GAIN" control* is on the left. Four crystal
sockets are to the right of the "METER SWITCH" and
are identified by the channel l etters "A," "B," "C," and
(4) RADIO RECEIVER BC-624-A OR BC-624AM OR BC-624-C.-The radio receiver occupies the
other half of Case CS-SO-A or CS-SO-c. The top con­
tains the audio control, the relay control t, two receiver
tuning controls, four oscillator plate coil tuning screws,
the channel shifter release button, and sockets for the
four receiver crystals. (See fig. 2-1.)
(5 ) CRYSTAL UNIT CR-I/A.
(a) The fundamental frequency of each crystal
unit appears on the crystal nameplate.
( b) Receiver and transmitter crystals are mechan­
ically interchangeable but differ in frequency due to the
receiver intermediate frequency of 12 megacycles.
(c) Crystal Unit CRollA will operate satisfac­
torily in any ambient temperature within the limits
--4o°C and +50°C. ( -30°F and + 1 220F.)
Note
Crystal Unit DC-llA may also be used.
c.
RECTIFIER RA-62-B OR RA-62 -C.
( 1 ) Rectifier RA-62-B or RA-62-C is located in the
right-hand compartment of Chest CH-I72-A or CH1 72-B but is not secured to the chest as it must be
removed for operation.
(2) Rectifier RA-62-B or RA-62-C is a self-con­
tained unit used to furnish operating power for the
transmitter-receiver assembly. All control s and recep­
tacles are mounted on the lower front control panel.
The receptacles and controls, from left to right are as
follows: receptacle for 1 10/220-volt single phase,
40/60-cycle a-c input which is a straight plug in Recti­
fier RA-62-B and a twist lock plug in Rectifier RA-62-C;
a voltage selec t or switch with taps for input voltages
105, 1 1 5 , 1 2 5, 2 1 0, 230 and 2 5 0 volts; a power "ON­
OFF" switch; and a six-prong doc output receptacle.
Also located on the control panel, at the left of the
power "ON-OFF" switch, is a double-pole hinged-type
S e ct i on I
Paragra ph 4 b(1 )(d-4e(3)
main fuse container. The upper front'panel is removed
by taking out 6 flat-head screws which secure it to the
top cover. A "SPARE FUSE" container with 3-ampere
2 50-volt spare fuses is mounted on the outside of the
removable front panel.
( 3 ) Tubes for rectifying the a-c input voltage to
the required three doc output voltages are two rectifier
tubes JAN-5U4G ( for plate supply) , one rectifier tube
JAN-6X5GT ( for bias supply), and one magnesium
copper sulphide rectifier, type IS36B7 ( for heater
supply) .
( 4 ) The 2 5-foot line cord for connecting the recti­
fier unit to the a-c power source is contained, with the
rectifier unit, in Chest CH-l72-A or (CH-I72B ) .
d. ANTENNA AN-94-A, AN-94-B OR AN-94-C
AND CORD CD-950-A.
( 1 ) Antenna AN-94-A, AN-94-B or AN-94-C is
used with Radio Set SCR-624-A or Radio Set SCR-624-B
and is packed with Cord CD-950-A in Chest CH-I70-A
or Chest CH-I73-B.
( 2 ) The antenna is a J-type antenna with a long
(radiator) section and a short (matching) section
mounted in a base for connection to Antenna Mast
MA-7-A. The long an<l short sections of the antenna
are telescopic for adjusting the length to accommodate
the transmitting frequency. On one end of Cord CD950-A is a small straight plug for connection to the
receptacle in the base of the antenna, and on the
other end is a large straight plug for connection to the
transmitter-receiver assembly.
, (3 ) The extended length of Antenna AN-94-A is
70-3/4 inches and the collapsed length is 26-3/S inches.
( 4) Antenna AN-94-C is electrically interchange­
able with Antenna AN-94-A or AN-94-B and is p acked
with Cord CD-950-A in Chest CH-I72-B. Antenna AN94-C is used with Radio Set SCR-624-B.
(5 ) The radiator element of Antenna AN-94-C is
22- 1 /2 inches long when extended and 1 7-7/S inches
long when collapsed.
e. ANTENNA AN-ISS AND CORD CD- 1 33 3 .
(1) Antenna AN-ISS is used with later models of
Radio Set SCR-624-B and is packed with Cord CD133 3 in Chest CH-I73-B .
( 2 ) The antenna is a broadband coaxial type radi­
ator with the lower end of the 3-inch diameter sleeve
designed to engage Antenna Mast MA-7-A. Cord CD1 333 is provided with Plug PL-2 59 on one end for con­
nection to the receptacle in the base of the antenna, and
with a large right-angle Plug PL-QI70 on the other end
for connection to the transmitter-receiver assembly.
( 3 ) AntenQa AN-ISS is mechanically interchange­
able and offers 'improved electrical characteristics over
Antenna AN-94-A, AN-94-B, or AN-94-C.
* The "GAIN" control has been eliminated on later models of
Radio Transmitter BC-625-A and all models of Radio Trans­
mitter BC-625-AM,
t The relay control has been replaced by the squelched control
on Radio Receiver BC-624-C.
1-5
AN 1 6- 40S C R 6 2 4 - 2
Secti o n s I - I I
Pa ra g ra ph s 4fh-I I - 1 a c l 1 )(f)
f. ANTENNA MAST MA-7-A.
( 1 ) Antenna Mast MA-7-A is contained in a strap
crate and two boxes. It is tubular plywood mast, 50 feet
high, used to support Antenna AN-94-A, AN-94-B,
AN-94-C or AN- I 8S.
( 2 ) The mast sections, with a boom section, are
packed in the strap crate. There are five l O-foot 1 0inch sections, one 4-foot 8-inch section, and four coup­
ling sleeve assemblies_ Clamped to one of the long mast
sections is a digging bar while in another long section
are four anchors.
( 3 ) The stays box contains all other accessories
and tools required for assembly and erection of the
mast ( refer to par. 2a, this sec. for a list of items con­
tained in the stays box) .
(4) The spare parts box contains items used only
for replacement and repair purposes.
g. CONTROL BOXES BC- 1I75-A, BC- l I 7 1 -A,
BC- I I 76-A, BC- 1 3 I 2 , BC-I3 1 3 AND BC- 1 3 1 4.
( 1 ) Only three control boxes are used in any one
installation. Control Boxes BC- 1 1 75-A, BC- t l 7 1 -A, and
BC- 1 l 76-A ( these contain no volume control ) , are fur­
nished with Radio Set SCR-624-A while the l ast three
Control Boxes BC1 3 1 2 , BC- 1 3 1 3 and B (;- 1 3I4 (thes e
contain a volume control and a socket) are furnished
with Radio Set SCR-624-B. They provide complete
control of communication functions.
( 2 ) The control boxes are packed for transporta­
tion in three compartments of the chest.
( 3 ) Control Box BC- 1 l 7 5 -A is used for master '
control and channel selection at the station location fOlr
Radio Set SCR-624-A. In use, it is mounted directly tOl
the center receptacle of the transmitter-receiver assem­
bly. Control Box BC- 1 3 I 2 replaces Control BOI x BC1 1 75-A in Radio Set SCR-624-B installation.
(4) COIntrol Box BC- l l 7 1 -A provides the send­
receive control and channel selection from a remote
point up to a maximum of 500 feet from the station or
RadiOl Set SCR-624-A, while ContrOll Box BC- 1 3 I 4 per­
forms a similar function for Radio Set SCR-624-B.
( 5 ) Control Box BC- l l 76-A provides a send­
receive control from a remote point up to a maximum
of two miles over telephone lines for Radio Set SCR624-A. Control Box BC- 1 3 1 3 is used as a replacement
for Control Box BC- 1 1 76-A in Radio Set SCR�624-B.
( 6 ) The control boxes also provide connection fOlr
land-phone communications between any twOl of the
three locations, utilizing Telephone EE-8-A or EE-S-B.
h.
L OU D S PEAKER LS- l O -A .-Loudspeaker LS- l O - A ,
LS- l O-B, or LS- 1 0C i s located u nder neath t h e three control boxes in the left rear of Chest CH- 1 7 3 -A or CH-
1 7 3 - B . . The loudspeaker is a self-contained u n it, wh ich
has
an
amplifier and rect i fier.
a leather ha ndle, LS- l O-B has
a
Loudspeaker LS- l O-A has
metal handle and LS- I O-C
has no handle.
SECTION II
INSTALLATION AND ADJUSTMENT
1 . P RE TRANSPORTATION CHECK.
-
Radio Set SCR-624-A or SCR-624-B is packed so that
it is easily transported by air. Prior to transportation,
take precautions to see that the equipment is in proper
operating condition as it is necessary that there be no
delay in establishing communication. Also prior to trans­
portation, perform the checks listed below.
a.
EQUIPMENT CHECK.-Check that each chest
and box contains the proper equipment as listed in
section I, paragraphs 2 and 3.
N ote
Two Batteries BA-30 should be In place in
Telephone EE-8-A or EE-8-B.
h. CHECK O F POWER. UNIT PE-7 5 -D.-1f the
auxiliary source of a-c power, the gasoline driven gen­
erator Power Unit PE- 7 5 -D, is to be used, see that there
is sufficient fuel for the gasoline motor.
C, BENCH CHECK FOR RADIO SET SCR-624-A
OR. SCR-624-B.
( 1 ) USING TEST EQU I PMENT I E- 1 9 - ( * ) .
1 - 6-2 - 0
N ote
Radio Set SCR-624-A or SCR-624-B is nor­
mally shipped from factory with all vacuum
tubes installed. When exceptions occur, install
the tubes according to the directions given in
section V, paragraph 5a( 1 ) .
(a) Place the transmitter-receiver assembly on
the test bench.
(h) Loosen the Dzus fasteners on the rack cov­
ers, raise the covers, and slide them away from the
center.
(c) Connect Control Box BC- 1 l 7 5 - A or BC- 1 3 I 2
to the I S-contact socket on the rack.
( d) Connect Rectifier RA-62-B or RA-62-C to
Power Unit PE- 7 5 -D or to a 40- to 6O-cycle, 1 00- to
1 30-volt or 200- to 260-volt source of a-c power, if
available.
( e) Connect Rectifier Unit RA-62-B or RA-62-C
to the 1 2 -contact socket on Rack FT-244-A by Cord
CD-809-A.
( f) Set the voltage selector switch on the recti­
fier to the proper input voltage.
Revi sed 27 May
1 94 9
I
AN 1 6-40S C R 6 2 4 - 2
N ote
Depress the small detent button at the top of
the voltage switch as the switch is turned in
order to change from the low voltage to the
high voltage side.
(g) Place the "LOCAL-REMOTE" switch on
the control box in the "LOCAL" positiOon.
(b ) Place the "ON-OFF" switch Oon the rectifier .
unit in the "ON" position.
(i) Place the "SEND-REC" switch at "SEND"
when using Radio Set SCR-624-B, or push the "PRESS­
TO-TALK" button when using Radio Set SCR-624-A.
These controls are located on the contrOoI boxes.
(j) Select channel "A" by means of the "A-B­
C-D-CHANNEL" switch on the cOontrOoI box. The top
channel slides on both transmitter and receiver fre­
quency shifter assemblies will be actu ated. If the shifter
mechanism dOo e s not operate when channel "A" is se­
lected, press the channel release buttOon 426 in Rack
FT-244-A because the mOotor may be stopped on an
open contact POosition.
(k) Make a similar check for channels "B," "C,"
and "D. "
(I) Connect Antenna AN-94-A, AN-94�B, Oo r
AN-94-C tOo Socket SO- 1 5 3 on the rack by means of
Cord CD-950-A, or connect Antenna AN- 1 98 tOo SOocket
SO- 1 5 3 by means Oo f Cord CD- 1 3 3 3 . Insert the proper
crystals for the pre-tuned channels in the transmitter.
(Refer to sec. V, par. 9a ( 2 ) . ) Select channel "A" Oon
the control bOox.
( m ) Set up Field Strength Meter 1-95 - ( * ) and
extend the antenna on the meter to the desired l ength,
depending on the strength Oof. the signal. Turn the
"ON-OFF" switch on the meter tOo "ON." Adjust the
"ZERO ADJ." control soo that the "RELATIVE FIELD
STRENGTH" meter Oon the field strength meter reaches
zero . . Set the "TUNING" dial Oon the field strength
meter to the frequency of the transmitter and adjust the
dial for a maximum reading Oon the "RELATIVE
FIELD STRENGTH" meter.
(n) Connect a microphone tOo the proper termi­
nal and speak into the microphone. There should be a
slight. increase in the reading Oof the indicating meter Oon
Fidd Strength Meter 1-95 - ( * ) , indicating mOodulatiOon.
. ( 0 ) . DOo not change the setting of the transmit­
ter "GAIN" cOontrOoI if it is locked with glyptal Oor with
a locking nut. If the control is not IOocked, advance, if
necessary, tOo secure modulation.
The "GAIN� ' cc;>ntrol has been eliminated on
later models of the radiOo transmitter.
N ote
(p) Repeat step ( 1 1 ) above on channels "B,"
"C," and "D." If any channel operates improperly or if
the channel frequencies have to be changed, retune in
accordance with the instructions in section V, 9a.
* Refers to
any issue.
Section I I
Para gra ph 1 ( 1 } (g)-H2 ) ( h )
( q) Place crystals of the proper Ooperating fre­
quency in the channels tOo be used ill the receiver. ( Refer
tOo sec. V, par. 9d( 3 ) (b) . )
( r) Select channel "A" Oon the cOontrol box.
(s) Place the "SEND-REC-SEND" switch on
Control Box BC- 1 3 1 2 in the "REC" position. Control
Box BC- 11 75-A is in the receive position when die
"PRESS-TO-TALK" button is not depressed. COonnect
a head set to the prDper audiD Ooutput.
(t) Set the receiver "AUDIO" control ( 2 3 6 ) and
the "RELAY" control ( 2 37 ) tOo their maximum clock­
wise position.
(u) With no signal applied, turn the "RELAY"
control ( 2 3 7 ) counterclockwise until there is a sharp
cut off of the signal.
( v) Return the "RELAY" cDntrol ( 2 3 7 ) to the
maximum clockwise positiOon. Apply a small signal
Df proper frequency frDm Signal Generator . 1-1 30-A
through Cord CD-477 to Socket SO- 1 5 3 Dn Rack FT244-A. The signal should be h eard in the head set.
Repeat this step Oon channels "B," "C," an d "D."
( w) If prOoper OoperatiDn of any channel is nOot
obtained Dr if . the frequencies are to be changed, retune
in accordance with the instruction in sec. V, par. 9d.
( 2 ) USING TEST EQUIPMENT IE-36.
(a) Place the transmitter-receiver assembly on
the test bench.
(b) Loosen the Dzus fasteners on Rack FT244-A, raise the covers slightly, and slide them away
from the center.
( c) Plug ContrOoI Unit BC- 1 303 into the 18cDntact socket on the rack.
(d) COonnect Rectifier RA-62-B Oor RA-62-C to
the 1 2 -contact socket on Rack FT-244-A by Cord CD809-A.
( e) Turn the "OFF A-B-C-D" switch on the
Control Unit BC- 1 303 to "A." The top channel slides
on both transmitter and receiver frequency shifter as­
semblies ,will be actuated.
(f) If . the shifter mechanism does not operate
when channel "A" is selected, press channel release
button 42 6 Oon the rack because the motOor m ay be
stOoP ped Dn an open contact pDsition.
(g) ,Make a similar check for channels "B," "C,"
and "D."
(b) Plug Phantom Antenna A-29 into Socket
SO- 1 5 3 Dn the . rack.
(i) Insert the proper crystals or the pre-tuned
channels in the transmitter. (Refer to sec. V, par.
9a( 2 ) (b) . )
(j) Turn the "OFF A-B-C-D" switch on the con­
trol unit tOo "A."
(k) Throw the toggle switch on contrDI unit tOo
"T." The lamp in the phantom antenna will light.
(/) Plug Microphone T-34 Dr T-44 into Cord
CD- 1 1 69. Plug Cord CD- 1 1 69 intD the cOontrDI unit. If
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Fig u re 2 - 2
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MA S T SEC TI ON
(5 REq 'D 10 : '0 · LONG)
(I REQ 'O 4 '- 8 " LONG)
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(4 REQ'o)
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STRAIGH T
(4 REQO)
1 COMPONENTS COMMON TO OL D AND NEW MA STS .
D COMPONENTS USED WITH EARLIER MAS TS, NOW OBSOL E TE .
m COMPONENTS USED WITH PRESEN T MAS TS
[B D SUPPLIED WITH RA DIO SET SCR - 624 - A *
[e.TU SUPPL IED WITH RADIO SET SCR- 624 - B
){SHACKLES
(6 REQ'o)
*' L A TER RA DIO SE TS SCR- 624 -A MAY HA VE SOME COMPONENTS
COMPONENTS
FROM
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Figure 2 - 2 .
rI
(I REq'b. )
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II AND
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A n te n n a M as t M A - 7-A-Com p o n enls
2 -3
A N 1 6-405 C R 6 2 4 - 2
Section I I
Para gra p h s 1 ( 2 ) ( m ) ( v)-2 b ( 2 )
Microphone T- 1 7 is used, plug it directly into t� e
control unit. Speak into the microphone. The lamp 10
the phantom antenna should increase in brilliance, indio
cating . modulation.
.
( m ) Do not change the position of the trans·
mitter "GAIN" control if it is locked with glyptal or
with a locking nut. If it is not locked. advance if neces·
sary to secure modulation.
N ote
The "GAIN" control has been eliminated on
later models of the transmitter.
(n) Repeat step ( e) on channels "B," "C," and
"D." If proper operation on any channel is not ob­
tained, retune in accordance with the instructions in
sec. V, par. 9a.
( 0 ) Place crystals of the proper operating fre·
quency in the channels to be used in the receiver. (Refer
to sec. V, par. 9d( 3 ) . ) .
(p) Insert the probe end o f Cord CD- 1 1 70 in
the "ANT" j !lck on the control unit and clip the alli·
'
gator clip on the other end of the cord to the center
pin of socket 4 1 6 on the rack.
(If) Place the "OFF A·B·C·D" switch of the
control unit in position "A."
(rJ Throw the toggle switch on Control Unit
BC- 1 303 to "R." Plug Head Set HS-33 or equivalent
into the jack marked "TEL" on the control unit.
(s ) Set the receiver "AUDIO" control (236)
and the "RELAY" control ( 2 3 7 ) to their maximum
clockwise position.
(t) With no signal applied, turn the "RELAY"
control ( 2 3 7 ) counterclockwise until there is a sharp
cut off of signal.
(u) Return the "RELAY" control ( 2 3 7 ) to the
maximum clockwise position. Tum the "SIG GEN'
switch on Control Unit BC- 1 303 to the "ON" position .
A tone should be heard in the head set. Repeat this
step for channels "B," "C" and "D."
(v) If any channel operates improperly or if the
frequencies are to be changed, retune the equipment
according to the instructions given in sec . V, 9d.
2.
I NSTALLATI O N .
a . CHOICE OF SITE.-In choosing a site for erec·
tion of Radio Set SCR-624.A, or SCR-624-B, make cer·
tain that the site is not over 500 feet from a telephone
line ( if telephone line connection is required ) , and not
over 50 feet from an a·c single phase power source of
40 to 60 cycles at 100 to 1 30 volts or 200 to 260 volts
( Power Unit PE· 75-D may be used when no power line
is available ) . Select a well cleared area, sufficiently large
for assembly and erection of the antenna mast (see fig.
2- 3) ; and one that is fairly level, with a slope not ex·
ceeding one foot (rise or fall) in seven feet distance.
h. ARRANGEMENT OF EQUIPMENT ON SITE.
( 1 ) Thoroughly clear an area approximately 2 6
feet i n diameter.
( 2 ) Place the stays box and spare parts�box near
the center of this cleared area. In one direction from
the center of the cleared area provide additional cleared
space for a distance of approximately 60 feet in length .
In width, gradually taper it from 2 6 feet at center
location to 4 to 6 feet at the far end of the area. (See
fig. 2- 3 . )
*
CH - 170 - � - SVPPLlEO WfTll
RII DIO SEr SCR - 6 2 4 - 11 ONL Y.
. -------...
2-4
-
"
F ig u re 2 - � .
A n ten n a M as t M A - 7-A-L o c a t i o n a n d A s s e m b l y S i z e
AN 1 6-40S C R 62 4 - 2
( 3 ) In a cleared space and within 25 feet in any
direction from the antenna base, place Chest CH- I 72-A,
or CH- I 72-B and Chest CH- 1 73-A or CH- 1 73-B. Un­
pack the chests, boxes, and crate, and visually inspect
components for p o s sible damage during transportation.
Check to see that there are two Batteries BA-30 in­
stalled in Telephone EE-8-A or EE - 8 -B .
c.
ASSEMBLY OF ANTENNA MAST MA-7-A.
( 1 ) To erect the plywood mast and antenna and
adjust the antenna (see figs. 2-5), proceed as follows:
(See figs 2-5 and 2-6.) Estimate the approximate cen­
ter of the 26-foot diameter cleared space. Drive a stake
lightly into the ground at this point. Place the loop end
of the radius rope (see fig. 2-2) over the stake, extend­
ing it in the direction where the 60-foot clearance has
been provided . At the far end of the radius rope locate
the position of the first anchor. (See fig. 2-2.) Take the
anchor from the plywood mast section in which it has
been transported. Two sets of anchors are furnished:
one set resembling corkscrews for use in soft soil, the
other set consisting of straight rods suitable for hard
or frozen soil. Select the anchors required and place
the duplicate set in the spare parts chest. At the end
COAXIIU..
��-�
ftMs(4
r 'sec
- :r)TION
•
Y£l./.. OW ALIGNMENT M4RX5
(10 '-10')
M.4S T ':;Q;TIO/V
BOOM
(/0',.10" ,tfIlST
.seCTIOII)
Section I I
Paragraph 2 b(31-2cl3)(bl
of the radius rope, turn the anchor down into the
ground until its top ring projects about 2 inches above
the ground . Using the radius rope, find the proper
location for the second corkscrew anchor, directly op­
posite the first anchor, and place it. In the same manner,
locate and place the third and fourth anchors from side­
to-side at right angles to the first two. Remove the cen­
te r stake and center the base plate over the hole in the
ground from which this stake was removed. Using this
stake and the three other stakes from the stays box, per­
manently secure the base plate to the ground. Drive
the stakes; through the holes in the base plate, into the
ground to their full length. Be sure that the base plate
assembly is so positioned that its mast-end projection
(see figs. 2-4A and 2-5) is horizontal and in the direc­
tion of the mast clearance space where the first anchor
was placed.
( 2 ) Lay out on the ground in the following order,
beginning at the base plate the mast section and coup­
lings from the strap crate.
(a) 1 mast section, 10 feet 10 inches.
(b) 1 coupling sleeve assembly (plain) .
( c) 1 mast section, 10 feet 10 inches.
(d) 1 coupling sleeve, with eyebolts.
(e) 1 mast section, 10 feet 10 inches.
(f) 1 coupling sleeve (plain) .
(g) 1 mast section, 10 feet 10 inches.
(h) 1 coupling sleeve, with eyebolts.
(i) 1 mast section, 4 feet 8 inches.
( 3 ) Assemble the mast sections as follows:
(a) Take the mast-bottom clamp from the stays
box and place it on the end of the first mast section
nearest the base plate. The notch of the clamp must be
away from the mast section and toward the base plate.
(b) If Antenna AN-94-A, AN-94-B, or AN-94-C
is to be used, take Cord CD-950-A from Chest CH1 70-A or CH- I 73-B. If Antenna AN- 188 is to be used,
take Cord CD- 1 3 33 from Chest CH- 1 73-B. Thread th e
ANTENNA
CA P
ANlFNNA
ELEMENTS
(G)
L OWER
Figure 2 - 4A .
A n te n n a M as t M A - 7- A-A s s e m b ly
Details
Figure
2-4B .
A n te n n a
A N - I 88-A s s e m b led
2-5
AN 1 6 -40S C R 6 2 4 - 2
Section / I
Pa ra g ra p h 2 ( 3 ) ( cI-2 ( 3 ) ( 1I
small straight-plug-end of the cord, beginning at the
base-plate-end, through the mast sections and couplings
(without fitting the sections together) , as laid out 'in
the above order.
( c) If Antenna AN-94-A, AN-94-B, or AN-94-C
is to be used, take it from the chest. Be careful to avoid
damage to the antenna in handling and assembly.
Couple the small straight plug of the coaxial cable to
the receptacle in the base of Antenna AN-94-A, AN94-B, or AN-94-C. (See fig. 2-4, A .)
(d) Insert the base of Antenna AN-94-A, AN94-B, or AN-94-C into the outer mast end of the outer
mast (4-foot 8-inch) section. (See fig. 2-4, A.) This an­
tenna must be adjusted following table 2 - 1 before the
mast is erected.
(e) If Antenna AN- 188 (see fig. 2-4, B) is to be
used, leave it in Chest CH- 1 73-B until Antenna Mast
MA-7-A is ready to be erected because the lower an­
tenna elements might be damaged on the ground.
(f) Fit the mast sections and couplings together
in the following manner:
1. Insert the remaining end of the 4-foot 8inch mast section into the coupling sleeve assembly
which has eyebohs, making sure that the yellow marks
are in line and that the coupling is on the mast section
down to its center hub. [ A snug fit will be obtained
when the yellow line on the mast is adj acent to the
yellow mark on the coupling (see fig. 2-4, A) . ]
2. Insert the end of the outer lO-foot l O-inch
mast section into the coupling as far as possible noting
the yellow line alignment as described for the preced­
ing mast section.
3. Continue in this manner for all remaining
mast sections. Then securely tighten all coupling clamps
of the coupling sleeve assemblies but do not tighten the
mast end clamp (see fig. 2-4, A.)
- TOP
$TIIY (8LAU)
Figure 2 - 5 .
2-6
BOTTOM
N ote
The yellow marks on the mast sections and
coupling sleeve assemblies must align to in­
sure proper position of eyebolts on the coup­
ling sleeves with respect to the anchors, there­
by avoiding the possibility of twisted or tan­
gled stays in the erection of the mast.
(g) Place the assembled mast over the mast end
assembly of the base plate. Make sure that the �otch
of the clamp and the slot of the mast end assembly
align to permit bringing the coaxial cable out of the
mast through the notch of the clamp. Securely tighten
the mast end clamp.
(h) Place the remaining lO-foot l O-inch mast
section on the boom fitting of the base plate, laying the
section on top of the mast. Place the boom-end assem­
bly into the other end of the mast section. (See fig.
2-4, A.)
(i) Take the four black stay ropes and four
5 / 1 6-inch shackles from the stays box. Attach the snap
fasteners of the stay ropes to each of the four eyebolts
of the outer mast coupling sleeve by means of the 3/8inch shackles.
(j) Take the four orange stay ropes and four
3/8-inch shackles from the stays box, and couple to the
innermost ( center) coupling sleeve in the same manner.
Make sure that the black and orange stays ( with turn­
buckles on both ends) are used on the boom anchor
side of the mast. These stays with an additional turn­
buckle permit greater tightening of the stays attached
to the boom anchor.
(k) Take the two guy ropes (boom vang ropes)
from the stays box and attach to the free end of the
boom with snap fasteners.
(/) Take four large shackles ( 1 /2 inch ) and the
four ring and chain assemblies from the stays box. By
STAY (ORANGE)
A n te n n a M as t M A - 7-A-A s s e m bled
Section I I
Fig u re 2-6
AN 1 6-40SCR624-2
(AN -94-A, B or e
AN TENNA
ANTENNA
AN-IS8
COUPL ING
SLEEVE
(WitH
EYEBOLTS)
(BLACK)
TOP STAYS
BOOM TIP
t'lSSEMBLY
F igure 2 - 6 .
A n ten n a M as t M A - 7-A-Ere cted
2- 7
Se cti o n I I
Paragraph 2(3)(1)-2'(2)
AN 1 6-405 C R624-2
means of one of these shackles attach the ring of the
ring and chain, one each, to each anchor. With the
exception of the anchor to which the boom will be
attached, the stays, one long (black) and one short
(orange) are attaChed to the other three anchors. Take'
one long stay and one short stay, the ones leading from
the mast in the direction of the appropriate anchor,
and attach them to the chain on the anchor by means
of a snap fastener. Estimate the required length of chaln
needed, placing the shackle in the link required to give
that length. Attach the remaining long and short stays
leading from the eyebolts on the top-side of the mast
to the boom tip fitting by means of snap fasteners using
the end hole of the boom tip. The boom vang ropes
are also attached here. The other hole in the boom tip
is for attaching the boom end to the chain in the boom
anchor and for the block and tackle hook. Fasten the
free ends of the boom vang ropes, stretching them
tightly, to the side anchors by means of a snap fastener.
(m) Take the block and tackle from the stays
box. Hook the triple-sheave block through the top of
the boom anchor. Make sure that the ring and chain
are ready to attach to the end of the boom when the
mast is elevated. Antenna AN-94-A, AN-94-B, or AN94-C must be adjusted for proper transmitting condi­
tions (see fig. 2-4 and table 2-1 ) . If Antenna AN- I88
is used it must now be assembled, see paragraph 2 c this
section.
d. ADJUSTMENT OF ANTENNA AN-94-A, AN94-B, OR AN-94-C.-To transmit efficiently, adjust the
telescopic sections of Antenna AN-94-A, AN-94-B or
AN-94-C according to the following tables:
TABLE 2 · 1 . ADJUSTMENT OF ANTENNAS AN·94 ·A,
AN ·94 ·B, or AN·94·C FOR OPTIMUM
EFFICIENCY.
ANTENNA AN-94-A
Transmitting
Frequency
Short Element
100/ 125 mcs
22-112 inches
70- 1/2 i\lches
1 14/ 140 mcs
19- 1/2 inches
6 1- 1/2 inches
12 5 / 1 56 mcs
17- 1/2 inches
5 3-1/2 inches
Long Element
ANTENNA AN-94-B OR AN-94-C
Transmitting
Frequency
Short Elem'tnt
(AN-94-B or AN-94-C)
Long Element
AN·94·B only)
100/ 12 5 mcs
Sliding section fully ex­
tended.
Section extended to en­
graved figure 3
1T'f/ 140 mcs
Sliding section extended
to engraved figure "2".
Section extended to en­
graved figure "2".
125/ 156 mcs
Sliding section fully tele­
scoped.
Section fully extended to
engraved figure " 1".
e. ASSEMBLY OF ANTENNA AN- I88.-R emove
the disassembled parts of Antenna AN- I88 from the
lid of Chest CH- I 73-B and assemble diem. The short
element is the upper element which screws into the an­
tenna cap. The other six identical elements are the lower
elements which screw: into six holes on a ring around
the lower portion of the antenna body. (See fig. 2-4, B.)
Note
Antenna AN- I88 requires no adj ustment.
f. ERECTION OF ANTENNA MAST MA-7-A.
( 1 ) If Antenna AN-94-A, AN-94-B, or AN-94-C
is used it should be ibserted into the top of the mast
according to subparagraph c and adj usted according to
2-8
·"
".
Long Element
(AN-94-C only)
Middle section fully ex­
tended. Small section ex­
tended to engraved figure
'� 3" .
Middle section fully ex­
tended. Small section ex­
tended to engraved figure
"2 ".
Middle section fully ex­
tended. Small section ex­
tended to engraved figure
" I ".
subparagraph d. The mast and antenna should now be
erected by use of the block and tackle.
( 2 ) If Antenna AN- I88 is used, Antenna Mast
MA-7-A should be slightly elevated off the ground.
Then couple the small straight plug of the coaxial cable
to the receptacle in the base of Antenna AN- I 88. Insert
the base of the antenna into the outer mast end of the
outer mast section .
CAUTION
Do not lay r-f Cord CD-950-A or Cord CD1 3 3 3 where it will be stepped on or run over
by any vehicle. Such treatment will increase
r-f losses in the line and reduce the power
output.
S e cti o n I I
Pa ra g r a p h s 2g(7)-4 a c
AN 1 6 -405 C R 6 2 4 - 2
g. INTER CONN ECTIO N OF ASSEM BLIES.
( 1 ) Connect the equipment as shown in figures 2-7
or 2-8. Inasmuch as the length o f Cord CD-950-A or
Cord CD- 1 3 33 from the antenna mast is only 2 5 feet,
set up the transmitter-receiver assembly a little less than
25 feet from the mast to allow for flexibility.
( 2 ) Place Chest CH- 1 73-A or CH- 1 73-B on any
conveniently located table or on the ground. Place
Chest CH- I 72-A or CH- I 72-B adj acent to and to the
left of Chest CH- 1 73-A as the connecting cable ( Cord
CD-809-A ) from Rectifier RA-62-B to Rack FT-244-A is
only 6 feet long. Place Rectifier RA-62-B or RA-62-C,
2 5 feet or less from the nearest a-c power supply source
because the power line cord is only 2 5 feet long. If re­
mote operation up to two miles is desired, place the
chest within 500 feet of a telephone line if lines already
set up are to be used, because the cable ( Cord CD8 I O-A) is only 500 feet long. Now the equipment
should be in such position that the sides of Chest CH1 72-A or CD- I 72-B are accessible, to permit connection
to and reeling of the 5 00-foot cable.
( 3 ) Remove Rectifier RA-62-B or RA-62-C from
Chest CH- I 72-A or Chest CH- I 72-B and place it on a
table or flat dry ground in front of the chest and with
its control panel accessible. Remove Cord CD-809-A
from Chest CH- 1 73-A or CH- 1 73-B. Place the 6-con­
tact plug of the cord into the 6-contact receptacle on
the rectifier control panel, and the 1 2-contact plug of
the cord into the left top receptacle of Rack FT-244-A.
Tighten both plugs by means of the knurled locking
ring on the plug. If either of the plugs are loose,
tighten the end ring with a spanner wrench from the
set of special tools. Do 110t connect the 25-foot power
line cord before consulting paragraph 3, tbis section.
( 4 ) Remove Control Box BC- 1 I 75-A from Chest
CH- 1 73-A (or Control Box BC- 1 3 1 2 in the case of
Radio Set SCR-624- B ) and place it into the 1 8-contact
( center) receptacle of Rack FT-244-A. Turn down tight
by means of the large locking ring on the bottom of
the control box. Connect the coaxial antenna transmis­
sion line ( Cord CD-950-A or Cord CD- 1 33 3 ) into the
remaining ( right hand) receptacle of the rack.
( 5 ) Remove the reel-end cover cap located on the
back of Chest CH- I 72-A or CH- I 72 -B. Unreel as much
of the 500-foot cable ( Cord CD-8 I O-A) as may be
needed . Turn the reel to such a position that two sides
of the socket flange are vertical. Place the speci al plug
of Cord CD-95 1 -A in this receptacle, making certain
that the locking edges of this special plug fully engage
the notches in the chest and the flanges on the plug
engage the reel socket, locking the reel to the chest
while the plug is attached. Remove this when more or
less cable is desired and to reel in the cable when the
set is dismantled . Place the remaining plug of Cord
CD-95 1 -A into the 1 2-contact receptacle of Control Box
BC- 1 1 7 5 -A or BC- 1 3 1 2 .
Revised 27 May
1 949
( 6) At the free end of the 500-foot cable attach
remote Control Box BC- l 1 7 1 -A or BC- 1 3 1 4 by insert­
ing the plug into the receptacle in the end of the con­
trol box. If operation at a more remote point, up to a
maximum distance of 2 miles, is necessary or desired,
connect the three terminals ("K," "COM., "TEL." ) of
Control Box BC- l 1 7 1 ·A (or Control Box BC- 1 3 14 when
�adio Set SCR-624-B is used) to a three-wire telephone
hne. Connect these telephone lines at the remote point
to the three terminals ( "K," "COM.," "TEL." ) of Con­
trol Box BC- 1 1 76-A ( or Control Box BC- 1 3 1 3 when
Radio Set SCR-624-B is used ) .
"
( 7 ) To any two o f the three control boxes connect
Telephone EE-8-A or EE-8-B for line of radio communi­
cation by means of Cord * CD- l 1 9 1 . Connect terminals
L1 and L2 of the telephone to terminals "TEL." and
"TEL." of remote Control Boxes BC- l I 7 1 -A, BC- 1 3 14,
BC- 1 3 1 3 or BC- 1 1 76-A, but on master Control Box
BC- 1 1 75-A or BC- 1 3 1 2 connect the telephone to termi­
nals "TEL." and "COM." ( the polarity is u nimporta nt)
In a noisy location, use Chest Set TD-2 and Head Set
HS- 3 3 in place of the handset of Telephone EE-8-A or
EE-8-B. Loudspeaker LS- l O-A, LS- l O-B or LS- l O-C may
be used at any of the control locations. The telephone
and loudspeaker may be used simultaneously if desired.
.
3.
ADJUSTMENTS.
a . Set the voltage selector switch on the control
pa � el � f Rectifier RA-6:-B or RA-62-C to the voltage
which IS nearest that avadable at the point of operation.
N ote
In order to switch from the low voltage ( 105,
1 1 5 , 125 volts) side to the high voltabe ( 2 1 0,
2 30, 2 5 0 volts ) side, press the small detent
button at the top of the voltage selector switch
in as the switch is turned.
b. After the voltage selector switch is set, be sure that
the "ON-OFF" switch on the rectifier is in the "OFF"
position and connect the a-c power line to the power
receptacle on the rectifier.
c. If the op rating frequencies have to be change d ,
�
r� tun � the r� celv � r and the transmitter according to the
d uectl O ns given 10 paragraph 9a, s ection V.
4.
A FTE R - I N STALLATION TESTS.
a. Turn the "ON-OFF" switch on the rectifier to the
"ON" position.
b. Select the operating frequency by means of the
"A-B-C-D-CHANNEL" switch on the control box and
10 cooperation with a similar station, send and receive
test signals.
'
.
c . At the conclusion of the tests, turn the "ON-OFF"
switch on the rectifier to the "OFF" position.
*
Cord CD- 1 1 9 1 is used with the control boxes of the 13 series and
Cord CD- 1 147 is used w ith the control boxes of the II series.
2-9
I
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A IVTENNA
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ANTENNA
AN-IBB
50 '
75FT. CORO(COAX/AL)
�D 950A FOR
AN-94-C
OR CORD C D - /333 1'O/l
CHEST SET
TO-2 AND HEAD SE T
ANTENNA
H S - 33 )
ANTENNA AN-/88
,.
Z
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,
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Fig ure 2 - 8 .
R a dio S e t S C R - 6 2 4 - B-In sta llatio n
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AN 1 6 - 40S C R 6 2 4 - 2
Section I I I
Para gra phs 1 a-2 d(21
SECTION ,n l
OPERATION
1 . START I N G A N D STO P P I N G THE EQU I PMENT.
a.
To start the equipment, turn the "ON-OFF" switch
'
on the control panel of Rectifier RA-62-B or RA-62-C to
the "ON" position. This turns on both the rectifier and
the transmitter-receiver assembly.
b. To stop the equipment, turn the "ON-OFF" switch
on the control panel of the rectifier to the' "OFF" posi­
tion. This turns off both the rectifier and the transmitter­
receiver assembly.
2.
NORMAL OPERATIO N .
N ote
Operation of this set is line of sight limited.
Check that there are no large metal obj ects,
mountains or other interfering obj ects between
the transmitting and receiving antennas be­
cause communication may become difficult or
impossible due to low signal strength or gar­
bled reception.
b. USING CONTROL BOX BC- 1 3 I 2 (USED WITH
RADIO SET SCR-624-B ) .
( 1 ) CHANNEL SELECTION.
(a) Set the "LOCAL-REMOTE" switch to
"LOCAL."
(b) Set the "A-B-C-D-CHANNEL" switch to
the desired frequency.
( 2 ) TRANSMISSION.
(a) Place the "SEND-REC.-SEND" switch in
either the momentary "SEND" or the fixed "SEND"
position.
( b) Press the lever switch on the handset or
operate the "ON-OFF" switch on Chest Set ID-2 to die
"ON" p osition, depending on whether the handset or
the chest-set is being used.
( 3 ) RECEPTION.
Note
The radio set is normally in the receive posi­
tion when the power is turned on. The equip­
ment returns to receive when the "SEND­
REC.-SEND" switch is released from the mo­
mentary "SEND" position."
a.
USING CONTROL BOX BC- 1 l 75 -A (USED
WITH RADIO SET SCR-624-A ) .
( 1 ) CHANNEL SELECTION.
(a) Set the "LOCAL-REMOTE" switch to
"LOCAL."
(b) Set the "A-B-C-D-CHANNEL" switch to
the desired channel.
( 2 ) TRANSMISSION.
(a) Press the lever switch on the handset and
the "PRESS TO TALK" button on the control box.
N ote
Chest S et TD-2 and Head Set HS-33 are
'
used in place of the handset, use the "ON­
OFF" switch on the chest piece instead of the
lever switch on the handset.
If
(b) Speak into the handset, microphone or chest
microphone.
( 3 ) RECEPTION.
N ote
Radio Set SCR-624-A or SCR-624-B is nor­
mally in the receive position when the power
is turn ed on. The equipment will return to
the receive position when the "PRESS TO
TALK" button and the lever switch on the
handset are released.
(a) Listen to a signal in the head set.
(b) A dj ust the receiver output by turning the
"AUDIO" control, located on Rack FT-244-A, with a
screw driver.
3-0
(a) Turn the "AUDIO" control on the radio re­
ceiver fully clockwise.
(b) Adjust the audio output by means of the
"VOLUME" control on the control box.
c.
USING CONTROL BOX BC- l l 7 1-A .
( 1 ) CHANNEL SELECTION.
(a) Place the "LOCAL-REMOTE" switch on
Control Box BC- 1 l 75-A in the "REMOTE" position.
(b) Set the "A-B-C-D-CHANNEL" switch on
Control Box BC- l l 7 1 -A to the desired frequency.
( 2 ) TRANSMISSION.-To transmit using Con­
trol Box BC- l l 7 1 -A, follow the instruction given in
paragraph 2a( 2 ) , this section.
( 3 ) RECEPTION.-To receive using Control Box
BC- l l 71 -A, follow the instruction given in paragraph
2a( 3 ) , this section.
d. USING CONTROL BOX BC- 1 3 14.
( 1 ) CHANNEL SELECTION.
(a) Place the "LOCAL-REMOTE" switch on
Control Box BC- 1 3 I 2 in the "REMOTE" position.
(b) Set the "A-D-C-D-CHANNEL" switch on
Control Box BC- 1 3 I4 to the desired frequency.
( 2 ) TRANSMISSION.-To transmit using Con­
trol Box BC- 1 3 I4, follow the instructions given in para­
graph 2 b ( 2 ) , this section.
AN 1 6-40S C R624-2
( 3 ) RECEPTION.-To receive using Control Box
BC- 1 3 14, follow the instructions given in paragraph
2 b ( 3 ) , this section.
( RECONTROL BOX BC- 1 l 76-A.
e " USING
MOTE . )
( 1 ) CHANNEL SELECTION.-Channel selection
is not polisible at this remote control box.
( 2 ) TRANSMISSION.-To transmit �ing �on­
trol Box BC- 1 l 76-A ( Remote) follow the lOstructlons
given in paragraph 2a( 2 ) , this section.
( 3 ) RECEPTION.-To receive using Control Box
BC-1 l 76-A ( Remote) , follow the instructions given in
paragraph 2a( 3 ) , this section.
f. USING CONTROL BOX BC- 1 3 1 3 .
( I ) CHANNEL SELECTION.-Channel selection
is not possible at this remote control box.
( 2 ) TRANSMISSION.-To transmit using Control
Box BC- 1 3 1 3, follow the instructions given in para­
graph 2 b (2 ) , this section.
( 3 ) RECEPTION.-To receive using Control Box
BC- 1 3 13, follow instructions given in paragraph 2 b ( 3 ) ,
this section.
3.
LAN D - L I N E
(TELEPHO N E ) COMMU N ICATION .
Remove the handset from the telephone case. Ring
the station by turning the magneto crank. Listen for an
answer. Press the lever switch on the handset. Speak
into the microphone. Release the lever switch to listen.
4.
DEFENSE A GA I N ST JAMM I N G .
a . GENERAL.-Jamming is the intentional genera­
tion by the enemy of radio signals designed to make
friendly signals unreadable and to surprise and confuse
the radio operators. The various types of jamming are
described in section VI, paragraph 2 .
b. PROCEDURE.-If bad interference i s received
and j amming is suspected, proceed as follows:
( 1 ) Remove the antenna from the binding post of
the receiver. If the noise level drops appreciably the in-
Secti o n s I I I - IV
Paragra p hs 213)17)-5 ab-IV- 1 a c
terference is coming from outside the receiver. If the
noise does not diminish there is something wronlf with
the receiver.
.
( 2 ) Report jamming immediately to the command­
ing officer.
( 3 ) Use a noise limiter when available. If no lim­
iter is available turn the receiver gain up as high as it
will go. To make this noise less hard on the ears put a
handkerchief between the ears and the head set or turn
the head set around so it is facing away from the ears.
(4) Change to an alternate frequency and call sign
if the primary frequency is badly j ammed. Tune up
quickly and accurately using a dummy antenna if one is
available. If not, tuna up at a reduced power.
( 5 ) Generally CoW is the most difficult to j am.
Also try tone telegraph. When using radiophones use
the phonetic alphabet and speak each word twice.
( 6 ) Beware of fake messages slipped into the jam­
ming by the enemy. In case of doubt authenticate. Don't
allow the enemy to distract your attention with con­
versation.
( 7 ) Do not shut down. That is exactly what the
enemy wants to happen, and it would let him know
that the j amming is effective. Practice, concentration,
and persistence will help the operator to work through
j amming many times stronger than the desired signal.
5.
D ISASSEMBLY A n E R OPERATIO N .
If further communication is not desired and the in­
stallation is to be disassembled and repacked, observe
the following cautions:
a. Detach the special plug in the receptacle in the
rear of Chest CH- I 72-A or CH- I 72-B, reel in the ex­
tended part of the 500-foot cable ( Cord CD-8 1 0-A),
and place the locking cap over the receptacle to prevent
the reel from turning while in transit.
b. When replacing Rectifier RA-62-A or RA-62-B in
Chest CH- 1 72-A or CH- I 72-B, make certain the bush­
ings on the bottom of the rectifier properly engage the
spike on the shockmount cradle in the chest.
SECTION IV
1.
THEORY OF OPERATION
G E N E RA L .
a.
Radio Set SCR-624-A (or SCR-624-B) provides
transmission or reception of amplitude-modulated r-f
energy of any one of four crystal-controlled frequencies
within the range of 100 to 1 5 6 megacycles. Only voice
communication facilities are available.
b. The average power output of the transmitter is six
to eight watts. The average sensitivity of the receiver is
3 to 4 microvolts for a 10 decibel signal-to-noise ratio.
c. Operation of Radio Transmitter BC-625-AM is
identical to the operation of Radio Transmitter BC625-A except that there is no slow release relay 1 30 in
Radio Transmitter BC-62 5-AM. There is no control of
the percentage modulation in some Radio Transmitters
BC-62 5-AM in which a fixed attenuator circuit has re­
placed the "GAIN" Control.
3 - 1 -4- 1
AN 1 6 - 40S C R 6 2 4 - 2
Section I V
Pa ra g ra p h 2 a-2d( 1 )
TRANSMI T TER
MOUNTING
E
1 68
"GA IN "
CON TROL
(/ 25)
*
A N TENNA
COUPL ING
CONTROL
THUMBSCREW
123 -
*Replaced by a fixed atte n u ator circuit in s o m e Radio Tra nsmitters BC-625-AM.
F i g u re 4 - J .
R a dio Tra-n s m mers B C - 6 2 5 - A and B C - 62 5 - A M -Top View
RADIO TRANSMITTER BC-6 2 5 -A
OR BC-6 2 5 -AM.
2.
a.
GENERAL.
( 1 ) Radio Transmitter BC-62 5-A and BC-62 5 -AM
employs a crystal-controlled oscillatQr circuit, the plate
circuit Qf which is tuned to' the crystal's second har­
mO'nic_ TwO' tripler stages fQllQW the QscillatQr and pre­
cede the final amplifier, thus making the final Qutput
frequency greater than the crystal fundamental by a
factQr Qf 18. The final Qutput stage is modulated by a
push-pull mQdulator driven by a pentQde voice am­
plifier.
( 2 ) The transmitter Qperates on any Qne of fQur
crystal-cQntrQlled channels lying within the frequency
range Qf 1 00- 1 5 6 megacycles. Channels are selected by
both IQcal and remote control.
( 3 ) When a channel is selected, the channel-control
ratchet mQtQr 406 located Qn Rack FT-244-A actuates a
frequency-shifter slide which autQmatically selects the
CQrrect channel crystal and tunes the transmitter cir­
cuits to' the desired frequencies. The crystal is chQsen
as the slide clQses the appropriate sectiQn "A," "B,"
"C." Qr D of crystal switch 1 5 6.
(4) The transmitter circuits are tuned by means of
a cam-and-shaft arrangement which enables the slide to'
adjust the crystal QscillatQr, the first and secQnd har­
mQnic amplifier, and the PQwer amplifier plate-capaci­
tO'rs to' a predetermined frequency setting.
"
"
h. OSCILLATOR.
( 1 ) The O'scillatQr tube JAN-6G6G (VT- 198-A) is
connected in a mQdified Pierce circuit in which the tank
circuit is prO'vided by the crystal CQnstants. Oscillations
will Qccur at the crystal fundamental regardless O'f the
4-2
frequency to' which the O'scillatQr plate circuit is tuned.
( 2 ) The tuned plate circuit comprises inductO'r 11 8
and variable capacitQr 1 14 and is adj usted to' reSQnate at
the crystal's secQnd harmO'nic. The plate Qf oscillatQr
tube JAN-6G6G (VT- 198-A) is electrQn-cO'upled to the
oscillatQry circuit comprising the control grid, the cath­
Qde, and the screen.
( 3 ) Grid bias is supplied by resistQr 1 5 1 - 1 . The
O'scillatiQns are sustained by the · impedance in the cath­
Qde circuit cO'nsisting Qf inductO'r 1 2 8-2 and bypass ca­
pacitO'r 103. CapacitO'r 102-1 CO'uples the screen to' the
cathode, and capacitO'r 101 supplements the control-grid­
to'-screen capacitance. The screen is biased by re­
sistQr 1 52 - 1 .
c.
FIRST HARMONIC AMPLIFIER.
( 1 ) The oscillatO'r output is cQupled to' the first
harmO'nic-amplifier tube JAN- 1 2A6 (VT- 1 34) by CQUP­
ling capacitO'r 104 and the parasitic-suppressing resistQr
1 5 0. .
( 2 ) The plate circuit Qf tube JAN- 1 2A6 (VT- 1 34)
consists O'f variable capacitQr 1 1 5 and the tapped in­
ductO'r 1 19 and is tuned to' the crystal's sixth harmO'nic.
The O'utput frequency Qf this stage is the third multiple
O'f the O'scillatO'r O'utput_
( 3 ) The doc plate vO'ltage is applied at the tap O'f
inductO'r 1 1 9. The vQltages appearing at the terminals
Qf this inductO'r are in CQrrect phase fQr alternately ex­
citing the grids O' f the push-pull secO'nd harmO'nic-ampli­
fier tube JAN-832 (VT- 1 1 8 ) .
d. SECOND HARMONIC AMPLIFIER.
( 1 ) The Qutput O' f the first harmQnic amplifier is
cQupled to' the grid Qf the secQnd harmQnic amplifier
thrQugh cO'upling capacitO'rs 1 09-3 and 1 09-4.
CONTROL
(/25 ) * * * �(
�
»
z
0I
"'"
o
VI
V T- 199
SPEECH AMP.
"'"
I
Co)
n
�
0t.)
"'"
I
t.)
* D e l eted in a l l later m o d e ls.
* * R e p l a c e d by 1 3 6- 1 , 1 3 6-2 , i n some tran smitters;
**"'Deleted i n R a d i o Tra n s m itters BC-625-A M .
****Deleted in later R a d i o Tra n s m itters BC-625-AM.
Figure 4 - 2 .
:!! VI
(Q
C
....
CII
Radio Tran s m itters B C - 62 S - A and BC-62S-A M-Fronf View
"'"
!l.
_.
0
::l
."
.!J <
F i g u res 4 - 3-4-4
Section I V
AN 1 6-405CR624-2
. D e l eted i n later R a d io Tra nsm iters BC-625-A M .
·.Deleted i n Radio Tra nsmitters BC-625-A M .
·.·Not u sed i n some tra n s mitters.
fig ure 4-3.
R adio Tra n s mitters
115
8C-625-A and 8C-625-AM-I.ar View
1 14
1 47
1 23-2 1 4 6
1 4 1 -3 1 4 1 -4 1 4 1 -1
-I !
13
-2
V
�1 1 8
I
H A R M O N I C AM P.
P L ATE CON TAC T < P U I ) OF
V T- 1 I 8 2 N D H AR M ON I C AM P.
P L AT E CO NT
.,. C P U 2) OF
V T- 1 I 8 2 N D HARM O N I C A M P.
· D e l eted from some tra nsmitters.
··Oeleted from Radio Tra nsmitters
BC·625·AM.
NOTE: SH()WING R-F DIODE INDICATOR TU8E VT-. 1 99 REMOVED
figure 4-4.
4-4
R a difJ Tran s m itters 8C-625-A and 8C-625 -AM-8oltom Oblique View
Sectio n I V
F i g u re s 4 - 5-4-6
AN 1 6-40S C R 624-2
156
!-----, I 6 6
CONTROL THUMBSCREW
*
167
'CON TA C T (PU2 )
- I /S POoNER AM�
CON TACT (PUI )
V T - I I S P O WER A MP.
1 63
* D e l e t e d in l o t e r m o d e l s .
Fig ure 4 - S .
R a dio Tra n s m itters B C - 62 S - A a n d B C - 6 2 S - A M -S h owin g
Lockin g Type A n ten n a C o u pling
Figure 4 - 6 .
R a d i o Tra n s m itters BC-62S-A and BC-62S - A M -S h owing
Non-Lo cking Type A nten n a Couplin g
4-5
Section IV
Para gra phs 2d( 21-3 a(21
A N 1 6- 40S C R 624-2
( 2 ) The rectified doc grid current develops grid­
bias voltage across r-f chokes 1 2 7- 1 and 1 2 7-2 and re­
sistors 1 32 - 1 and 1 32-2. R-F currents passing through
these chokes are bypassed to ground by capacitors 1 02-8
and 102-9.
( 3 ) The tank circuit consists of variable capacitor
1 1 6 and inductor 120 and is tuned to the third multiple
cf the first harmonic-amplifier output frequency, or the
1 8th multiple of the crystal fundamental.
(4) The doc plate voltage is applied at the center
tap the inductor 1 20. The voltages appearing at the
terminal of inductor 1 2 0 are in correct phase for alter­
nately driving the grids of the push-pull power-ampli­
fier tube JAN-832 (VT- 1 1 8 ) .
e . POWER AMPLIFIER .
( 1 ) The output of the second harmonic-amplifier
is coupled to the grids of the power amplifier through
coupling capacitors 109- 1 and 1 09-2 .
( 2 ) The power-amplifier input circuit resembles
that of the second harmonic-amplifier except for the
absence of 'the grid-bias resistors.
( 3 ) The output circuit consists of variable capacitor
1 1 7 and the center-tapped inductor 1 2 1 and is tuned to
the same frequency as the second harmonic-amplifier,
namely, the 1 8 th multiple of the crystal fundamental.
( 4 ) D-C plate voltage is applied at the center tap
of inductor 1 2 1 . This arrangement serves to balance
the push-pull output circuit. Coupling inductor 1 2 2 lies
between the two sections of inductor 1 2 1 . The degree
of coupling between the power-amplifier output circuit
and the antenna is varied by moving inductor 1 2 2 by
means of the antenna-coupling control. (See figs. 4-5
and 4-6.)
f. SPEECH AMPLI FIER.
( 1 ) The audio input originates from the micro­
phone through the rack and enters the transmitter
through terminals 1 and 2 of plug 1 2 3- 1 . The a-f input
is then impressed on terminals 1 and 3 of the primary
of input transformer 1 5 8 .
( 2 ) The secondary of this transformer is connected
to a bridge circuit comprising resistors 14 1 - 1 , 1 4 1 -2 ,
] 4 1 -3, and 1 4 1 -4. The bridge circuit is balanced s o that
it allows voltages from the secondary of the audio-input
transformer to excite the grid of the speech-amplifier
tube JAN-6SS7 (VT- 1 99) but at the same time prevents
a-f voltages from the receiver from also exciting the
speech-amplifier grid.
( 3 ) Potentiometer 1 2 5 serves as a gain control for
transmitter modulation only and is replaced in some
Radio Transmitter BC-62 5-AM by a fixed attenuator
circuit consisting of resistors 1 80 and 1 8 1 .
( 4 ) Tube JAN-6SS7 (VT- 199) is cathode-biased
by resistor 1 5 3-3 which is bypassed for audio frequen­
cies by capacitor 1 1 0.
( 5 ) Grid resistor 1 5 3-4 and cathode choke 1 62
( 1 62 - 1 in some models) block r-f energy from the sen­
sitive speech amplifier.
4- 6
(6) The plate is fed through audio choke 126 and
is coupled to the primary of the interstage transformer
1 59 by capacitor 1 1 3 . The frequency response is held
to desirable values by plate-loading resistor 1 44 con­
nected across the primary of transformer 1 59.
g. MODULATOR.
( 1 ) The secondary of the interstage transformer
1 59 is connected to the grids of the push-pull modu­
lator tubes JAN- 12A6 ( VT- 1 34 ) . Grid-bias voltage
from the bias dividers 145, 1 52-3 and 1 52-4 is applied
through the centertap terminal No. 4 of the transformer
secondary.
( 2 ) Capacitor 109-5 is connected in parallel with
the modulator grids and terminals 3 and 5 of the trans­
former 1 59 secondary and serves to reduce the high-fre­
quency response and suppress oscillations in the modu­
lator circuit.
( 3 ) D-C plate voltage is applied through the cen­
tertap terminal No. 2 of the primary of the modulator
transformer 1 60. D-C screen voltage is obtained through
terminal No. 2 of transformer 1 60 and dropping resistor
1 54-2 .
( 4 ) The audio voltage across the secondary termi­
nals of transformer 1 60 modulates the plate input of
power-amplifier tube JAN-832 ( VT- 1 1 8 ) .
h . METER SHUNT CIRCUITS.
( 1 ) The s i x - P 0 s i t i o n two-section "METER
SWITCH" ( 1 5 7 ) is connected to a network of shunts
which are listed together with the currents they aid in
measuring in section V, paragraph 9 h ( 9 ) as follows:
shunt 1 34 for first harmonic-amplifier plate current,
1 3 5 - 1 for second harmonic-amplifier plate current, and
1 48 for p ower-amplifier grid current. Switch position
6 is not used.
( 2 ) The control grid, the screen, and the suppres­
sor grid of the r-f* indicator tube are connected to­
gether to form the diode plate which terminates through
load resistor 1 54-3 * and by-pass capacitor 1 05-2 * and
the plate in turn is capacitively coupled to the power­
amplier tank circuit.
( 3 ) The test milliammeter when connected across
shunt 1 5 3-2 * , measures the plate-to-cathode rectified cur­
rent in the r-f indicator diode, and since the amplitude
of the diode depends on the r-f voltage developed in the
power-amplifier plate circuit, the test milliammeter indi­
cates tuning of the power-amplifier plate.
3.
a.
RADIO RECEIVER BC-624-A OR BC-624 -AM.
GENERAL .
( 1 ) Radio Receiver BC-624-A or BC-624-AM is a
superheterodyne receiver (see fig. 8-1 ) which operates
in the frequency range 1 00- 1 5 6 megacycles on any of
four present crystal-controlled channels. The inter­
mediate frequency is 12 megacycles.
( 2 ) After a channel has been selected by adjusting
switch 286 to "A," "B," "C," or "D," the channel-con­
trol ratchet motor 406 located on Rack Ff-244-A actu* Eliminated in later models of the transmitter.
AN 1 6- 40S C R 6 2 4 - 2
Sectio n IV
F i g u res 4-7-4 - 8
C A PA C I TOR
RECEIVER
MOUN TING HOLE
ALIGNMENT
248
"RELAY "
CON TROL
*" M " is stenciled on Radio Receiver BC·624·AM .
Fig ure 4 - 7 .
MOUN TING HOLE
"ECEIVER
2 88
R adio R e c eivers B C - 624-A and B C-624 - A M -Top Vie w
Fig ure 4 - 8 .
R a dio Receiver SC-624 - C-Top View
4-7
Section IV
Figure 4-9
AN 1 6-405 C R 6 2 4 - 2
DIODE RESONA TING COIL TUNING SCREW
3RD IF PL A TE RESONA TlNG ­
COIL TUNING SCREW
" AUDIO " C ONTROL
ADJU S TMENT SCREW
V T- 16 9, DE T,
AVC a: 1 S T AUDIO
V T - 209, 3 RD IF
3RD IF GRID
RESONA TlNG - COIL
TUNING SCRE W
" REL AY " C ON TROl..
A DJUS TMEN T SCREW
2 93
2 ND tF PLA TE
RESONA TING - C O I L
TUNING SCREW
12
V T - 209, 2 ND I F
2ND I F G RID
RESONA TlNG - COIL
TUNING SCREW
1 S T IF PL A TE
RE$ONA TlNG - COIL
TUNING SCREW
217A
H O LE FOR SET
SCRE W WREN CH
R F SECTION
MOUNTING SCRE W
figure 4 - 9 .
4-8
R a dio R e c eiv ers B C - 624- A a n d B C - 62 4 - A M -Rear View
J A N - 1 2S G 7
3 R D . I . F:
".
Z
JA N - 1 2G 8
A .V.C A N D
0I
.a:.
o
II'
n
:IIa
0...,
Ot _
. ,_
_
.a:.
2 N D AU DIO
I
...,
AU D I
S Q U E L C H C O N T RO L
LI M I TER
CO N T R O L
AU D I O
S W ITCH
AND
�
I
..0
NO IS E
OSC
A UD I O
AND
SQ U E LC H
D E L AY
A Y. C .
I ST A U D I O
""
_.
Fig ure 4 - r O .
CIt
CD
,..
... CD _ .
o
.a:. ::::1
(Q
C
I
R a dio R e c eiver B C - 62 4 - C-R e a r Vie v.
0<
Section IV
Pa ragra ph 3a(3)-3'(6)
AN 1 6-40SCR624-�
ates a frequency-shifter slide which automatically selects
. the correct channel crysta,l ,and tunes the receiver circuits
to the desired frequencies. The crystal is chosen as the
slide closes the appropriate section, "A," "B," " c," or
"D" of channel switch 286.
.
I
(3) The receiver circuits are tuned by means of a
cam-and-shaft arrangement enabling the slide to adjust
the following variable capacitors to a predetermined
setting: capacitor 2 16A in the r-f grid circuit, capacitor
2 16B in the r-f plate circuit, capacitor 2 16C in the
mixer grid circuit, capacitor 2 17A in the harmonicamplifier plate circuit, and capacitor 2 17B in harmonic
generator plate circuit.
h. R-F AMPLIFIER.
( 1 ) Inductor 22 1 couples the antenna to inductor
222 in the grid circuit of the r-f amplifier tube JAN900 3 ( VT-203 ) .
( 2 ) Inductor 222, variable capacitor 2 16A and
trimmer capacitor 2 1 8-1 comprise the tuned grid circuit
which is adjusted to resonate at the frequency of the
received carrier.
-
( 3 ) The grid is coupled to this tuned - circuit
through capacitor 201 which also serves to prevent the
AVC voltage applied to the grid from grounding
through inductor 222.
(4) The tune4 plate circuit consists of inductor
2 2 3 , variable capacitor 2 1 6B and trimmer capacitor
2 1 8-2.
( 5 ) Meter-shunt resistor 259 is connected across the
terminals of the receiver test-milliammeter �et 288.
(6) When the receiver is being tuned with a large
signal voltage applied to the input, circuit, the AVC
voltage <ieveloped is impressed as additional bias on the
control grid of r-f tube JAN-9003 ( VT-203 ) . This
additional bias reduces the plate current and causes a
decrease in the reading indicated by Test Set I- 1 3 9-A.
For a constant signal input, the plate current decreases
as the receiver circuits becOme better aligned.
c. CRYSTAL OSCILLATOR.
( 1 ) The crystal oscillator operates in the frequency
range · of 8 to 8.72 megacycles and utilizes one section
of the twin-triode tube JAN- 12AH7GT.
( 2 ) The crystal is connected in series between the
control grid and ground and is in parallel with grid
leak resistor 266- 1 .
( 3 ) Crystal switch 286 consists of four wafer sec­
tions, each of which is provided with contacts for
simultaneously selecting the desired crystal and the cor­
responding variable iron-core oscillator plate inductors
2 2 7- 1 , 227-2, 227-3, or 227-4� , Capacitors 204 and 205,
together with any of ,these . i�ductors provide the tuned
plate circuit of the oscillator. When a crystal is not in
use it is shorted to ground.
( 4 ) The plate inductors are tuned by, varying the
inductance by means of the adjustable iron cores.
( 5 ) Resistor 265 - 1 provides cathode bias for the
oscillator section of tube JAN- 12AH7GT (VT-207) and
is bypassed for radio frequency by capacitor 206-2.
4- 1 0
d. HARMONIC GENERATOR .
( 1 ) the r-f output of the crystal oscillator is
coupled to the grid of the harmonic generator tube
JAN-9002 ( VT-202 ) through capacitor 205. This grid­
driving voltage is comp aratively high and causes the
output of tube JAN�9002 ( VT-202 ) to be rich in har­
monic content.
( 2 ) Resistor 262 - 1 provides a doc grid return.
Cathode bias is obtained through resistor 261 which
is 'bypassed for radio frequency by capacitor 202- 1 5 .
( 3 ) The tuned plate circuit; comprising inductor
226, variable capacitor 2 1 7B and trimmer capacitor
2 1 8-5 , is tuned to that harmonic of the crystal-oscillator
output frequency which, when heterodyned with the
reCeiver frequency, will produce a frequency equal to
the intermediate frequency of 12 megacycles. For ex­
ample, if a 1 00-megacycle signal is received and an 8megacycle crystal is employed for the channel in use,
the harmonic-generator plate circuit will be tuned to the
eleventh crystal harmonic, or 88 megacycles, and the
difference in frequenC}' will be 12 megacycles.
( 4 ) Plate bypass capacitors 202 - 1 3 and 2 02 - 1 4 pro­
vide stable operation. D-C plate voltage is supplied
through resistor 260.
e.
HARMONIC AMPLIFIER.
( 1 ) Capacitor 203-2 couples the plate circuit of the
harmonic generator to the grid . of the harmonic-am­
plifier tube JAN-9003 ( VT-203 ) .
( 2 ) The plate circuit o f tube JAN-9003 ( VT-203 ) ,
comprising inductor 2 2 5 , variable capacitor 2 1 7 A and
trimmer capacitor 2 1 8-4, is tuned to the same frequency
as the output of the preceding stage.
( 3 ) Harmonic-amplifier tube JAN-9003 ( VT-203 )
serves merely to amplify the harmonic-generator output
sufficiently to provide adequate voltage for coupling to
the mixer grid.
( 4 ) Resistor 2 5 5-2 provides a doc grid return .
( 5 ) Cathode bias is supplied through resistor 2 5 3-2
which is bypassed for radio frequency by capacitor
202- 1 1
.
f.
MIXER.
( 1 ) Inductor 225 couples the harmonic-amplifier
output to the mixer . grid through inductor 224 and
capacitor 203- 1 .
( 2 ) The output of; r-f amplifier tube JAN-900 3
( VT-203 ) is also coupled to the mixer grid through
inductor 224 and capacitor 203- 1 .
( 3 ) The mixer gri d circuit, comprising inductor
224, variable capacitor 2 1 6C and trimmer capacitor
2 1 8-3, is tuned to the frequency of the received signal.
(4) Resistor 2 2 5 - 1 is the grid leak and reSistor 256
is the cathode-bias resistor.
. ( 5 ) Direct current plate and screen voltage is sup­
plied through resistors 263- 1 and 2 5 7 respectively.
( 6 ) The plate is · connected to the inductance-tuned
primary circuit of the i-f transformer assembly 291 .
This plate circuit, comprising the variable iron-core inRevised 1 7 July 1 95 1
Section IV
AN 1 6-405 CR624-2
ductor 22S- 1 and capacitors 207- 1 and 20S- 1 , is tuned
to ;;he intermediate frequency, 12 megacycles.
g. FIRST, SECOND, AND THIRD I-F.
( I ) RADIO RECEIVER BC-624-A.
(a) The mixer output is coupled to the grid
of the first i-f amplifier tube JAN- 12SG7 (VT-209)
through the secondary circuit of i-f transformer 2 91 .
This circuit is inductance-tuned ( by means of the ad­
j ustable iron core of inductor 22S-2 ) .
(b) Cathode bias is provided by resistor 26S
which is bypassed by capacitor 206-5. Th e voltage di­
vider consisting of resistors 267-2 and 267-3 provides
a stable screen voltage.
(c) The second and third i-f amplifier tubes
JAN- 12SG7 (VT-209 ) are connected in circuits similar
to that of the first i-f tube except that a screen-dropping
resistor 271 is used instead of a voltage divider in the
third i-f stage.
(d) Transformer assembly 292 couples the first
i-f plate to the second i-f grid, 293 couples the second
i-f plate to the third i-f grid, and 294 couples the third
i-f plate to the detector diode.
( e) Plate voltage for all r-f circuits appears at
terminal
3 of plug 2 3 1 .
Choke 24 1-2 and capacitor 202-16 filter any
(f)
extraneous r-f voltage from this high-voltage circuit. No
voltage appears on terminal 3 of plug 2 3 1 when the
transmitter is operating. Therefore, only the receiver
audio circuits are operative during transmission.
(g) Although i-f transformers 291, 292, 293 and
294 are given different reference numbers, they are elec­
trically and mechanically identical and may be used
interchangeability.
( 2 ) RADIO RECEIVER BC-624-AM.
(a) The operation of the i-f amplifier in Radio
Receiver BC-624-AM is essentially the same as in Radio
Receiver BC-624-A. The principal differences are in the
grid returns. The grid of the third tube JAN-12SG7
(VT-209 ) is returned directly to ground.
(b) An additional capacitor 2 1 1-2C has been
added to the grid return of the second i-f tube JAN1 2SG7 (VT-209 ) . These improvements serve to reduce
cross modulation due to grid currents on high noise
voltage peaks.
h. DETECTOR AND AVC CIRCUITS IN RADIO
RECEIVER BC-624-A.
( I ) The r-f voltage induced in the tuned secondary
circuit of transformer 294, variable inductor 22S-S and
capacitors 20S-S and 207-S, is applied to one of the
diode plates of detector tube JAN- 12C8 ( VT- I69) .
This r-f current is rectified in JAN-12CS and the audio
component appears across resistor 2S1, and potentiom­
eter 236, and resistors 2 77 and 27S. Capacitors 203-3
couples a portion of the r-f voltage to the other diode
plate of JAN- 1 2 CS.
( 2 ) Because of the voltage drop through resistors
277 and 276, the cathode of JAN- 12C8 is S.5 volts
Para g ra p h 3 9-3;(31
above ground. Since the AVC diode plate is returned
to ground, no rectified voltage will flow in the- AVC
circuit until the potential developed by the signal on
the A VC diode plate exceeds this cathode bias. As soon
as the r-f signal exceeds the cathode bias, the delay
voltage is said to be overcome, the A VC diode rectifies
the r-f signal, and the voltage drop through the re­
sistor 275-1 places a negative voltage at the j unction of
266-2 and 275- 1 . This negative voltage, varying with
the average signal voltage because of the smoothing
action of capacitor 2 1 1-C, is shunt fed to the grid of the
r-f amplifier, JAN-9003 (VT-203 ) , and series fed to
the grids of the first and second i-f amplifiers, JAN-
12SG7 (VT-209) .
( 3 ) Resistors 2 5 1 , 252, 267- 1 , and 267-4 are isola­
tion resistors which also serve to provide high resist­
-ance grid leaks to ground. Capacitor 202-2 bypasses
the r-f energy to ground.
i. DETECTOR, NOISE LIMITER, AVC DELAY
CIRCUITS IN RADIO RECEIVER BC-624-AM.
(I) In Radio Receiver BC-624-AM, the tuned cir­
cuit of the secondary of the last i-f transformer 294
feeds the r-f signal to the audio diode of the detector
tube JAN- 1 2CS (VT- 1 69 ) . The signal is rectified in
JAN- 12C8 and appears as a-f voltage across resistors
264-2 and 276-2 . . The average rectified carrier voltage
appears between the j unction of resistors 2 7 1 -2 and
272-2 and the cathode of tube
the filtering action of capacitor
combination with resistor 2 7 1 -2.
JAN- 1 2CS because of
2 l 1-2A and 2 1 1 -2B in
( 2 ) The noise limiter diode section o f tube JAN1 2H6 (VT-2 14) operates on the average voltage applied
to it which is of proper polarity for plate current to
flow. However, noise peaks appear at the plate of the
noise limiter diode as a sharp change in voltage in a
negative direction. Since the time constant of the re­
sistor 271-2 and capacitor 2 1 1-2A and 2 1 1-2B combina­
tion, whieh provides the average bias on the cathode
of the noise limiter diode, JAN- 12H6, is long with re­
spect to the highest audio frequency modulation of the
incoming signal, this bias remains essentially constant
with audio modulation. If a noise peak appears across
the diode load resistors 276-2 and 264-2, the noise
limiter diode plate is driven negative with respect to
the bias on its cathode. This causes the diode to cease
conducting; and, therefore, no voltage appears across
load resistor 2 72-2. Hence no signal appears on the
grid of the fiist audio amplified JAN-1 2CS. Since this
action is momentary, no deadening of the set is ap­
parent to the operator. The total effect is to produce
a noticeable reduction in the amplitude of the inter­
mittent noise bursts such as ignition interference.
( 3 ) The second plate of the diode, JAN- 12H6, and
its cathode . are utilized for delayed AVC . The plate of
this diode is coupled to the primary of the last i-f
transformer 294 through the coupling capacitor 20�-3.
The selection of the r-f voltage from the primary rather
than the secondary of the i-f transformer results in a
higher AVC voltage and serves to reduce the shunting
4- 1 1
A N 1 6 -40S C R 6 2 4 - 2
Section IV
F i g u re 4- 1 1
RECEIVER TUNINC
CONTROL LOCKNU T
___
TUNING
221
252
202- 1
201
251
26 1- 8
2 0 2- 3
254- 1
2 1 3 _____
2 2 3 --;.......
26 1-1 - ���---224
)K * *
**
213
225
"O U TP U T " LEAD
C O NNEC TED
HERE FOR
I F A LIGNMENT
2 0 2 - 6 -¥
251
"GND." L EA D
CONNECTED '
HERE FO R
IF A LIGNMENT
*257- 1 i n R a d i o Re �� iver BC-624-C.
* * N ot u s e d in R a d i o R e c e i v e r BC-624-C.
***252 - 1 in s o m e receivers .
* * * * 2 8 7 i n s o m e receivers.
Figure 4- J J .
4- 1 2
R a dio Receivers BC-624 - A , BC-624-AM a n d BC-624-C-Riglt r Side View
AN 1 6-40S C R 6 2 4 - 2
effect Qf the. AVC Qn the i-f secO'ndary and to' reduce the
modulatiQn rise in the a-f amplifier at the PO'int when
the signal . vO' l tage is just O'vercO'ming the AVC delay
bias. The pO'tential difference between the AVC diode
plate and ground, S.5 VO'lts, ' is established by the delay
diO'de tube JAN- 1 2H6 by which potential the applica­
tiQn O'f the AVC is delayed.
j. FIRST AUDIO-FREQUENCY AMPLIFIER.-The
pentO'de sectiO'n O'f JAN- 1 2CS (VT- 1 69 ) prO'vides the
first stage O'f audiO' frequency amplificatiO'n and alsO' pro­
vides interphO'ne cO'mmunicatiO'n. The a-f vO'ltage is fed
to' the amplifier grid thrO'ugh audiO' gain PO'tentiO'meter
236 and transfO'rmer 295 .
k. SECOND AUDIO-FREQUENCY AMPLIFIER.-­
The amplified a-f signal is resistance cO'upled to' the am­
plifier, JAN- 1 2J5GT (VT- 1 3 5 ) , the O'utput O'f which is
cQupled to' the IO'ad thrO'ugh transfO'rmer 296. This
transfO'rmer is tapped fO'r impedance matching at ter­
terminal 7, 4000 O'h ms ; terminal 6, 300 O'hms; and
.
minal 5, 50 O'hms.
I. AUDIO SQUELCH .
( 1 ) The purpose O'f the squelch circuit is to' keep
O'bj ectiQnable nO'ise O'ut O'f the receiver headsets when
nO' carrier is being received.
( 2 ) One triO'de sectiO'n O'f JAN- 1 2AH7GT (VT207) is used to' O'perate the audiO' squelch relay 246. A
PQrtiO'n O'f the doc cO'mpQnent O'f the audiO' vO'ltage, de­
velQped at the audiO' diQde O'f the secO'nd detectQr JAN1 2 CS ( VT- 1 69 ) when an r-f carrier is being received,
is cQupled to' the grid O'f tube JAN- 1 2AH7GT. The
audiO' vO'ltage variatiQns are smoothed O'ut by capacitO'r
206- 1 6 leaving O'nly the average value Qf the rectified
vQltage to' be applied to' the grid O'f the audiO' squelch
tube.
( 3 ) The cathQde Qf this triO'de sectiO'n O'f tube JAN12AH7GT is connected to' a bleeder-resistQr netwO'rk
cO'nsisting O'f resistO'rs 2 79- 1 , 279-2, 2S2 and potentiQm­
eter ( relay cQntrO'I ) 2 37. This netwO'rk, cO'nnected
between plus 300 VO'lts and grO'und, puts a positive
vO'ltage Qn the cathO'de, the PO'tential Qf which may be
cQntrolled by PO'tentiQmeter 237.
(4) AdditiO'nal grid bias is determined by the mag­
nitude O'f the doc cQmponent Qf the diode current flQw­
ing thrO'ugh resistO'r 279-3 and therefO're varies with
the strength Qf the signal carrier.
( 5 ) The audiO' squelch tube is biased nearly to' cut­
Qff, and O'n received signals, the additiQnal bias cuts O'ff
current through JAN- 12AH7GT, and relay 246 is re­
leased. With nO' signal the bias is removed, current
again flQWS in the tube, and relay 246 closes. With the
relay CQntacts clQsed the audiO' vO'ltage from the diode
! AN- 1 2 � (VT- 1 69 ) is shO'rted to' ground. The O'pen109 Qf thIS relay CQntact restO'res the receiver Qutput to'
nQrmal.
(6) The bias Qn the squelch tube JAN- 12AH7GT
is regulated by PO'tentiQmeter 2 37 and thus the sensi­
tivity O'f the squelch circuit is adjusted.
4.
Secti o n IV
P a r a g ra p h s 3(31;-4d 1 I
RADIO RECEIVER BC-624-C.
4.
GENERAL.
( 1 ) RadiO' Receiver BC-624-C is a mO'd lficatiQn O'f
RadiO' Receiver BC-624-AM with majO'r changes in the
AVC, squelch, and audiO' amplifier circuits.
( 2 ) MinQr changes have been made in certain re­
sistances previO'usly used in Qrder to' increase the O'ver-all
gain and thus imprQve the AVC characteristics.
( 3 ) In additiO'n, resistQrs which were fO'und to' be
O'verheating in the fQrmer receiver were replaced in
RadiO' Receiver BC-624-C by twO' resistO'rs in parallel.
,A paper capacitO'r was substituted fQr capacitor 2 1 2 .
, Circuits changed in the later type receiver are described
in the fQllO'wing paragraphs.
h. DETECTOR AND AVe.
( 1 ) Signal vO'ltage develQped in the secondary cir­
cuit Qf the last i-f transfQrmer 294 is applied to' O'ne
diO'de sectiO'n Qf tube JAN- 12H6 (VT-2 14) mO'unted
underneath the chassis O'f the receiver.
( 2 ) AudiO' vO'ltage is develO'ped acrO'ss resistO'rs 290
and 2 76-2. The average rectified vO'ltage O'f this diQde
is utilized as AVC vO'ltage effectively in series with the
vO'ltage develO'ped by the paralleled diodes in vacuum
tube JAN- 1 2CS. The radiO' frequency vO'ltage rectified
by this latter tube is derived frO'm the primary circuit O'f
the last i-f transfO'rmer to' secure an additiO'nal gain in
vO'ltage.
( 3 ) NO'rmally the negative AVC vO'ltage applied to'
the grids O'f the r-f and i-f stages increases with an in­
crease in signal strength. The applicatiQn Qf increasing
amO'unts Qf negative AVC vQltage serves to' increase the
grid bias and thus reduces the sensitivity O'f the receiver.
(4) WithO'ut any system to' delay this functiO'n, the
weak signals plus the added nO'ise compO'nents furnish
enQugh AVC vO'ltage to' reduce the sensitivity O'f the re­
ceiver to' the pO'int where the signal WQuld be inaudible.
In Qrder to' avO'id this reductiQn O'f sensitivity to' weak
signals in the presence Qf nO'ise cQmpO'nents, the AVC is
held at a cO'nstant potential until the signal level reaches
a sufficiently high predetermined value. After this
level
.
is reached the AVC O'perates nQrmally.
( 5 ) The AVC delay tube JAN- 12AH7GT (VT207 ) , when nO' signal is present, receives a positive- VQlt­
age O'n its plate frO'm the cathode circuit O'f the AVC and
secO'nd audiO' tube JAN- 1 2 CS (VT- 1 69 ) . As IO'ng as
this vO'ltage equals Qr is greater than the cathQde bias
O'n the delay sectiO'n O'f tube JAN- 12AH7GT, the tube
conducts and the vQltage drO'Pping acrO'ss resistO'r 2 5 S-2
maintains the AVC bus at a slightly positive PO'tential.
This positive AVC vQltage serves to' increase the r�f
and i-t sensitivity. The AVC delay sectiO'n O'f tube
JAN- 1 2AH7GT, in additiQn, prO'tects the r-f and i-f
tubes by limiting the maximum PQsitive PO'tential that
can be applied to' their grids.
c.
NOISE LIMITER.
( 1 ) One-half O'f tube JAN- 1 2H6 (VT-2 14) is used
as a series limiter. The audiO' signal can get to' the audiO'
4- 1 3
.co
t Circuit symbol n ot used on Radio Receiver BC-624-C.
.c-
t Circuit symbol n ot used on Radio Receiver BC-624-C.
N OTE: Tu be J A N - 1 2A6 a n d an a d d itio n a l t u b e JAN - 1 2AH 7GT
have been a d d e d to Radio Receiver BC-624-C.
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* Not used in Radio Receiver BC-624·AM .
'*Th ese c a p a citors a r e mou nted o n a n e w assembly o n Radio
Receiver BC-624-AM and a r e called 2 1 1 - I A. - l B. - I C.
Mou nted on s a m e assem b l y is a n ew ca pacitor 2 1 1 -2A. -2B.
-2C.
NOTE: Tube J A N - 1 2 H 6
BC-624-AM.
Figure 4 - J 2 .
has
been
added
to
Radio
Receiver
R a dio R e ceivers BC-624-A, BC-624 - A M
a n d BC-624-C-Fro n l View
*Becomes 264- 1 in Radio Receiver BC-624-AM.
**Becomes 272- 1 in Radio Receiver BC-624.A M .
***Becomes 2 76- 1 in Radio Receiver BC-624-A M .
Fig ure 4 - J 3 . R a dio R e c eivers BC-624-A, BC-624 -AM
and BC-624 - C-Fron l Obliq u e View
Section I V
F i g u re 4- 1 4
AN 1 6 - 40SCR624-2
�1)2- 11
"' D e l eted from Radio Receiver BC-624-C.
**257- 1 in Radio Receiver BC-624-C.
* D e l eted from Radio Receiver BC-624-C.
**257- 1 in Radio Receiver BC-624-C.
Figure 4- J 4
-
R - F Oscillator A ssem bly
4- 1 5
Section IV
Paragra p h 4c121-4d(3)
AN
1 6- 40S C R 62 4 - 2
amplifier grid only by passing through this noise limiter
tube. This diode will pass the audio signal only when
conducting. Moreover, conduction takes place only
when the plate is positive with respect to its cathode.
During the reception of signals the average rectified
voltage appearing at terminal 2 of the i-f transformer
294 is negative.
( 2 ) Because of the voltage drop across resistor
2 76-2, the potential at the plate of the noise limiter
section of tube JAN- 1 2H6 is positive with respect to its
cathode. On noise bursts, the plate of the tube is driven
negative while the cathode is held at the original po­
tential by the charge on the filter capacitors 2 1 1 -4B and
202-28 and the tube ceases to con duct. Conduction is
resumed when the noise impulse has passed and the
plate again becomes positive with respect to the cathode.
The filter capacitors 2 1 1 -4B and 202-28 resume their
quiescent charge and the tube operates normally, if the
noise continues, the filter capacitor charges sufficiently to
again place the cathode potential lower than the plate
and the tube operates normally, transmitting both the
desired signal and the sustained noise.
( 3 ) The audio signal passed by the series limiter
is developed across resistor 2 8 1 -3 and is then passed by
the coupling capacitor 206- 1 7 to volume control 236.
d.
( 2 ) The doc voltage developed by the rectification
of the r-f signal in the detector circuit is utilized by the
audio squelch tube to determine whether the bias on the
first audio amplifier will be such as to allow that tube
to respond to the audio signals on its grid.
( 3 ) When a signal is being received, its average
doc rectified value from the detectors is applied through
resistor 2 74- 1 to the grid of the audio squelch tube, one
section of tube JAN- 12AH7GT ( also used as the oscil­
lator) . The voltage at the grid of the squelch tube with
no signal being received is positive by the amount of the
delay bias which reaches it through resistors 276-2, 290,
280-2 , and 2 7 1 -2 from the high end of the cathode bias
resistor 2 77-2. The position of the squelch bias poten­
tiometer 238A in operation is set such that current
through the squelch tube is not cut off until a signal of
sufficient strength to develop the necessary negative bias
Note
I N PUT
SQUELCH.
( 1 ) A squelch circuit is incorporated in order to
silence the receiver when no signal is being received or
when the signal is sufficiently below the noise level to
be unusable.
For convenience in tuning the receiver with a
buzzer or similar source of radio frequency
R . I'".
energy, the noise limiter circuit may be dis­
abled by rotating the squelch control 238A
to its maximum clockwise position, thus open­
ing switch 2 38B.
2
203-3
6
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figure 4 - J 5 .
4- 1 6
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121 1 - 2B
S U P P RES SOR
J AN-IZH6
A+
2 7 6- 2
2 6 4- 2
21 1 -IC
236
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206
- 24
2 0 6-1 7
TO
AUDIO
R a dio R e ceiver B C - 624 - A M -S im plified S c lt e m atic o f A VC a n d Nois e S u ppre s s or
AN
Section IV
F i g u res 4- 1 6-4- 1 7
1 6-40S C R 6 2 4 - 2
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274 - 1
MODIFICATION
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FIELD
A P PLYING
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M O D I F IC A T I O N S .
M O D l f l C. A T I O N S
ONL Y .
MODIFICATIONS
FIELD
THESE
THIS
ONLY.
MODIFICATIONS
COMPON E N T S
WIRING
THESE
REMOVED
ADDED.
PA R T S
ADDEO.
R a dio R e c eiver 8 C - 624 -A-R e wirin g o f 'h e S q u elch Circuit
I/O
Mle.
212
C/fEW
MlC.
*
* *
***
BC-624-A M
Replaced i n later R a d i o Tra n s m itters
by fi xed resistors 1 80 and
21 1-1A
N o t used i n a l l tra nsm itters
Becomes
t
IrECEIVER DFT. OUTPUT
i n Radio Receiver
181
BC-624-A M
Figure 4- J 7 . Simplified Diagram 0' th e
****
Radio Receiver
BC-624-AM
BC-624-C
Nat u s e d i n R a d i o Receiver
R a d i o Receiver
1
C
VT- /69
INTe/fPJlON� .t
RECEIVEIf /1A1Pi.IFle/f
BC-624-C
c h a n g e s shown in red
Tran s m itter- R e ceiver M icrop h o n e M ixing
Circuit
4- 1 7
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W I R I N G OF RF 3 - StC T/ON
VA R IA B L E: C A P A C I T O R
�------ B R --------,
VT-ZOJ . RF'
(9003)
VT-Z03. MIXER (9003)
NOTE :
3�SECT'ON VARIABLE CAPACITOR
t 216A , Z I6 B . 216 C) NOT SHOWN.
W I R I N G OF OSC. Z - S E C T I O N
VA R I A B L E: CA PACI T O R
NOTE :
SOCKET TU8ULRR SHIELD TO
BE SOLDt!RED TO CONDo SHIELD
ON ,tIL L 4 SOCKETS .
l'lDIU..Z .. SECTION VARIABLE CAPACITOR
(ZI7A . ZI7SJ NOT SHOWN.
*2 54- 1 , - 2 . not used in Radio Receiver BC-624-C_
," i g u re 4 - 1 8 .
Receiver R - F a n d Os cillator A ssembly-Wirin g Diagram
III
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Section IV
F i g u re 4- 1 9
AN 1 6 - 40S CR624-2
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R e c eiver I-F Transform ers-Wiring Diagram
4-1 9
Section IV
P a ra g ra p h 4d(41-4eI31
A N 1 6- 40S C R 6 2 4 - 2
is received. This latter adj ustment is manual and may
be varied to silence the receiver output at any signal
below 2 to 10 microvolts .
(4) When the negative bias applied to the squelch
tube is s u fficiently high to cut off plate current through
this tube, the flow of current through resistor 2 75-4 be­
comes zero, and the potential on the grid of the first
audio tube becomes substantially the same voltage as
that appearing at the junction of resistors 285 and 2 73-3.
Under this condition, normal operation of the first audio
stage takes place, whereas with a current flowing in re­
sistor 2 75-4, the grid of the first audio tube is negative
with respect to the cathode and the tube becomes in­
operative.
.
( 5 ) The first audio stage operates as a cathode fol­
lower with a gain of less than one ( resistor 285 is used
for cathode load and bias ) . Although this mode of op­
eration inherently limits distortion, some will occur at
the point where the squelch circuit just cuts off. The
plate voltage for the squelch tube and the first and sec­
ond audio amplifiers is filtered by the resistance ca-
pacitance combination, resistor 2 64-3 and capacitor
2 I 2A. This permits deletion of the choke 269B used
in Radio Receiver BC-624-AM.
e.
SECOND AND THIRD AUDIO STAGES.
( 1 ) Audio voltage supplied from the first audio
stage through capacitor 206-25 and resistor 272-1 is
applied to transformer 295.
(2) The output of the secondary winding is then
applied to the grid of tube JAN- 12C8 through resistor
2 5 7-2 and radio frequency choke 241-4. Cathode bias
for this tube is provided by resistor 277-2 (screen circuit
bypassing) .
( 3 ) The audio voltage applied to the last stage is
developed across the plate load resistor 2 66-4 and is
coupled by capacitor 2 06-2 6 to the grid of tube JAN1 2A6 ( VT- 1 34 ) . Resistor 2 5 8-3 is a grid leak. Cathode
bias is provided by resistors 2 3 5 - 1 and 2 3 5 -2, paralleled
to increase the total wattage dissipation capabilities .
Capacitor 2 1 2D is an audio bypass around the cathode
bias circuit.
R E Q U lf N
A C T U A 'f!
40
R A -r C H £ T
SPRI NG
406
A DJ ,
NG
C RE W
ADJ.
DJ .
N
SPRiNG
SWITCH
TR A N S M I
SC R E W S
CO V E R
*Relay 4 1 1 -2 h a s cover on later m o d e ls.
Figure 4 - 2 0 .
4-20
M OU N T I N G
R a c k FT-244 -A-Cen ter Cover R e m o ved-Top View
$ C fl E W ;S
AN 1 6-40SCR624-2
(4) To improve the output regulation of the third
audio stage, some negative feedback is introduced
through resistor 240. The output circuit is matched to
the final audio stage by means of transformer 200.
( 5 ) Two impedance levels are available for the
connection of both high and low impedance headsets.
Tap 4 matches from one to twelve pairs of 600 ohm
headsets connected in parallel ; tap 5 similarly matches
one to twelve paralleled 8000 ohm headsets.
5.
RACK FT- 2 4 4 -A.
(See figures 4-20 and 4-2 1 .)
Rack FT-244-A fits over the transmitter and re­
ceiver. The complete assembly is held together me­
chanically by eight mounting screws. (See fig. 2-1, also
refer to sec. I, par. 4 b.)
a.
h. All input and output connections to the transmitter
and receiver are made through the rack. (See fig. 4-20,)
The filtered doc output is applied to the transmitter and
receiver through socket 420. The master control box is
connected to socket 4 1 7. The transmitter r-f output of
receiver signal input is made through socket 4 1 6. Re­
ceiver plug 2 3 1 engages rack socket 4 19. Transmitter
plugs 1 2 3 - 1 and 1 2 3-2, respectively, engage rack sockets
4 1 8 - 1 and 4 1 8-2. By means of these connections, the
rack functions. as a junction box which interconnects
the transmitter and receiver and the other units of the
equipment.
c. The channel-control ratchet motor 406 and the
antenna-changeover relay 4 1 2 are respectively the means
by which it is possible to actuate the frequency-shifter
mechanism and to alternate the mode of operation be­
tween reception and transmission.
d. The ratchet wheel of the channel control motor
406 is equipped with four arms spaced 90 degrees apart.
The motor is so positioned that a ratchet-wheel arm will
release a frequency-shifter actuating slide when the
ratchet wheel is displaced one tooth past the point where
the opposite arm first opens a pair of positioning-switch
contacts 42 7A, B, C, or D. In this position of the motor
assembly, the contacts remain open. When a channel is
selected, the solenoid of motor 406 receives operating
power through terminal 4 of socket 420. The motor
solenoid and the interrupter switch cause the armature
to oscillate; and the pawl, which is part to the armature
assembly, rotates the ratchet wheel. As this wheel ro­
tates, the arms attached to it displace the frequency­
shifter actuating slides in the order "A," <tB," "C," "D"
and open the contacts of the positioning switch 427, in
the same order. When the positioning switch contacts
"A," "B," "C," or "D," which correspond to the chan­
nel selected on the control box, are opened, the motor
circuit is broken and the process of channel-selection
ceases. When this happens, the ratchet wheel arms will
have displaced the actuating slide, and consequently the
receiver and transmitter shifter slides for the desired
channel to the position where the proper crystals are
chosen and the circuits tuned.
e. When the pushbutton switch 426 ( the release but-
Sectio n IV
P a ra g ra p hs 4e(41-6a(41
ton) is depressed the motor solenoid is energized and
attracts the armature. When the armature is released,
the pawl attached to it displaces the ratchet wheel one
tooth which is just sufficient to cause the complete re­
lease of the channel slides. There is no contact what­
ever between the actuating slides and the channel slides.
This is the only condition of the frequency-shifter mech­
anism which permits removal of the transmitter or re­
ceiver from the rack without damaging the equipment.
f. Now if release pushbutton 426 is pressed a second
time, the ratchet wheel is again displaced one tooth and
the ratchet-wheel arm is completely disengaged from the
positioning switch contacts or the channel in use. This
doses the motor circuit again, and channels are selected
in the order "A," "B," " C," "D" until the channel pre­
viously selected on the control box is reached. There­
fore, the release pushbutton 426 makes it possible to
release the frequency-shifter mechanism and to select a
channel again without touching any control on the con­
trol box.
g. Locking relay 4 1 1 - 1 is connected across the motor­
voltage supply and is energized whenever the motor is
energized. When the contacts of locking relay 4 1 1 - 1 are
dosed, the antenna-changeover relay 4 1 2 is energized
and switches the antenna to "RECEIVE." This pre­
vents transmission while channel selection takes place.
When the antenna-changeover relay is in the unener­
gized state, the transmitter-receiver assembly is con­
nected for transmission. ( See par. 8, this section, for a
detailed description of the control circuit and the B+
circuit switching effected by means of the antenna­
changeover relay 4 1 2 . )
6.
RECT I F I E R RA- 6 2 - B A N D RA-62-C.
a. GENERAL.-Rectifier RA-62-B or RA-62-C is de­
signed to supply power from a 1 10- or 220-volt, single
phase 40-60-cyde, a-c power source, and to supply direct
current for the operation of Radio Set SCR-624-A equip­
ment. (See fig. 8-1 .)
( 1 ) The doc output voltages supplied are the fol­
lowing:
(a) The plate supply is 300 volts at 230-milli­
amperes.
(b) The bias supply is 1 5 0 volts at 8-milli­
amperes.
(c) The heater supply is 1 3 volts at 3.9 amperes.
( 2 ) The a-c input voltage is rectified by means of
the following rectifier elements:
(a) The plate supply is rectified by two rectifier
tubes JAN-5 U4G (VT-244 ) .
(b) The bias supply i s rectified by one rectifier
tube JAN-6X5G (VT- 12 6-B) .
( c) The heater supply is rectified by one magne­
sium copper sulphide rectifier ( IS36B7 ) .
( 3 ) All outputs are completely filtered to prevent
radio interference in the transmitter-receiver assembly.
(4) The high-voltage circuit of Rectifier RA-62-B
or RA-62-C has a time delay feature, preventing the ap-
4-21
AN 1 6-405CI624-2
Section IV
F i g u re 4 - 2 1
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plication of plate and bias voltage to the radio equi�­
.
ment until the filaments are suffiC1ently heated. This
requires 10 to 15 seconds, during which time the plate
voltage will measure zero at the power supply.
( 5 ) An automatic carbon-pile voltage regulator
controls the heater supply voltage. This regulator does
not affect the high-voltage supply.
(6) The rectifier will operate at any ·ambient tem­
perature within the range of minus 50 to plus 70 de­
grees C. (minus 58 to plus 150 degrees F). At minus
50 degrees C. ( minus 58 degrees F) the ripple voltage
of the plate and the bias voltage does not increase more
than 60 percent, and the heater voltage ripple does not
increase more than 1 50 percent.
h. A-C INPUT.
( 1 ) Rectifier RA-62-B has a male a-c input plug
which is flush with the face of the panel, but the Recti­
fier RA-62-C has a recessed male twist plug for a-c
input.
( 2 ) The power transformer is a doubl e-primary
type having six input voltage selector taps for a-c i nputs
of 105, 1 1 5, 125, 2 1 0, 230, or 2 50 volts.
( 3 ) Each primary winding is individually fused
with 3-amj>e re, 2 50-volt fuses. The proper a-c input
voltage is selected by a 3-hole, 6-position switch. This
switch connects the power transformer primaries in
parallel at the 105-, 1 1 5-, and 1 2 5 -volt po sitions , and in
series at the 2 10-, 230-, and 2 50-volt posi tions. When
it is in the "ON" position the single-pole, single-throw
"ON-OFF" toggle switch connects the power trans­
former primary to the a-c input receptacle.
c.
D-C HEATER VOLTAGE OUTPUT.
( 1 ) The a-c voltage from the power transformer
secondary terminals 19 and 20 is rectified by the mag­
nesium copper sulphide rectifier.
( 2 ) The rectified voltage, now pulsating doc, is
filtered by the .01-henry . choke and the two 6000microfarad capacitors, resulting in a ripple voltage of
not more than 2 percent.
( 3 ) A voltage regulator holds the heater output
voltage constant over a wide range of input and load
voltages.
(4) The voltage is maintained within the limits of
12.6 to 13.5 volts at it load of between 2. 75 and 5.0
amperes.
( 5 ) Terminal 4 of the 6-contact receptacle is the
plus 1 3-volt heater output connection.
d.
D-C BIAS VOLTAGE OUTPUT.
( 1 ) Heater voltage for the rectifier tube JAN6X5GT (VT-1 26-B) is supplied by terminals 14 to 1 5
o f a secondary winding o f the power transformer. Al­
ternating current voltage from terminals 16 and 18 of
one of the power transformer secondaries is rectified
by tube JAN-6X5GT (VT-126-B) .
( 2 ) The pulsating doc voltage, obtained at terminal
1 7 of the winding and at the 'cathode of this tube, is
filtered by two chokes and a three-section capacitor. The
Sectio n IV
Para g ra p h s 60(5)-7&(4)
values of the uoits in this three-section capacitor are 10,
1 5 , and 30 microfarad. The ripple voltage does not
exceed 0.2 5 percent.
( 3 ) Terminal 1 of the 6-contact receptacle is the
minus 150 volt bias supply connection. The bias circuit
is fitted with Ii relay so that, in the event of bias failure,
the plate supply voltage is removed. This relay closes
the plate supply voltage (plus 3 1 0 volts) circuit at not
more than 100milliamperes and opens the circuit at not
more than 4-milliampere flow through the relay coil.
e. D-C PLATE VOLTAGE OUTPUT.
( 1 ) The heater voltage for the two rectifier tubes
JAN�5U4G (VT-244) is supplied by terminals 9 and 10
of a secondary winding of the power transformer.
( 2 ) Alternating current voltage from terminals 1 1
and 1 3 of one of the power transformer secondaries is
rectified by tubes JAN-5U4G (VT-244) .
(3) The pulsating do c voltage, obtained at ter­
minals 12 and 9, is filtered by a 10-henry choke and a
30-micr�farad capacitor. A 1 5,000 ohm bleeder resistor
is connected across this capacitor. The ripple voltage
does not exceed 0.3 percent.
(4) Terminal 2 of the 6-contact receptacle is the
plus 3 1 O-volt plate supply connection.
7. CONTROL BOXES.
Note
Control Boxes BC- 1 175-A, BC- 1 1 71-A, and
BC- 1 176-A are used in Radio Set SCR-624-A,
while Control Boxes BC� 1 3 12, BC- 1 3 1 3, and
BC- 1 3 1 4 are used in Radio Set SCR-624-B.
a. GENERAL.
( 1 ) In general, the control boxes function as junc­
tion boxes and as transmit-receive control at three dif­
ferent points of operation.
( 2 ) In addition to these functions, Control Boxes
BC- 1 1 75-A, BC- 1 171-A, BC- 1 3 1 2, and BC- 1 3 14 also con­
trol channel selection. (See figs. 5-6, 5-7, ' 5-8 and 5-1 O.)
h. CONTROL BOX BC- 1 175-A.
( 1 ) Control Box BC- 1 1 75-A is supported by and
connected to the 18-contact receptacle of Rack FT-244-A.
( 2 ) Depressing the "RADIO PRESS TO TALK"
push button (220) energizes relay 228 in Control
Box BC- 1 1 75-A causing Telephone EE-8-A or EE-8-B
through binding post 225-3, to be connected through
the resistor network 226- 1 , 226-2, and 227 to the input
transformer 1 5 8 of Radio Transmitter BC-625-A.
(3) Releasing this push button de-energizes the
relay 228, switching the telephone to the output trans­
former-296A of Radio Receiver BC-624-A, and energizes
the relay 4 1 2 of Rack FT-244-A which in turn switches
the antenna and plate supply to the receiver circuits.
(4) Placing the "LOCAL-REMOTE" switch (223)
in the "LOCAL" position connects the "COM" binding
post 225-2 to "CHANNEL" control switch 224, permit­
ting channel selection only at Control Box BC- 1 1 75-A.
4-23
Section IV .
Paragraphs 7b(5''':'' S a( 1 )
,
A N 1 6-40SC R 62 4 .. 2
( 5 ) Placing the switch 223 in the "REMOTE" po­
sition disconnects "CHANNEL" control switch 224 of
Control Box BC- 1 175-A and connects it, through con­
tact 2 of Cord CD-95 1-A, to "CHANNEL'� control
switch 2 1 1 of Control Box BC- l 17 1-A. This permits
channel selection at the 500-foot control point ( Control
Box BC- l 17 1-A) instead of at Control Box BC- 1 175-A.
( 6 ) Placing the switch on any contact of channel
control switCh 224, grounds the appropriate contact of
the ratchet motor control circuits in Rack FT-244-A.
Thus the channel selector circuits controlled by the
ratchet motor are operated until the contact is me­
chanically opened, and the desired channel is selected.
CONTROL BOX BC l 17 1-A.
( 1 ) The binding posts "K," "COM" and "TEL"
and "CHANNEL" selector contacts are connected to
the equivalent contacts in Control Box BC- 1 175-A
through the 500-foot, eight-conductor Cord CD-S I0-A.
( 2 ) "RADIO PRESS TO TALK" push button 2 10
operates in the same manner as push button 220 on Con­
trol Box BC- 1 175-A which is described in paragraph
7. b, this section.
( 3 ) "CHANNEL" control switch ( 2 1 1 ) will oper­
ate only when "LOCAL-REMOTE" switch 223 on Con­
trol Box BC- 1 175-A is in the "REMOTE" position.
The function of switch 2 1 1 then t>e<:omes similar to
"CHANNEL" control switch ( 224 ) ' as described in
paragraph 7.b; ( 6 ) , this section.
d. CONTROL BOX BC- 1 176-A ( REMOTE ) .
(l ) Binding posts "K," "COM." and "TEL." of
Control Box BC- 1 176-A are connected to "K," "COM.,"
and "Te!." binding posts of Control Box BC- l 1 7 1-A by
means of a three-wire telephone ( 2 mile maximum ) line.
( 2 ) The only control on Control Box BC- 1 176-A
is the "RADIO PRESS TO TALK" push button ( 200 )
which operates in the same manner as push button 220
on Control Box BC I 175-A. This function is described
in paragraph 7.h. ( 2 ) , this section.
e. CONTROL BOX BC- 1 3 12.
( 1 ) Control Box BC- 1 3 1 2 is supported by and con­
nected directly to the IS-contact receptacle of Rack
FT-244-A.
( 2 ) Throwing the "SEND-REC." switch ( 220) to
"SEND" position energizes relay 22S in Control Box
�y1 3 12 causing Telephone EE-S-A or EE-S-B, through
sacket 2 3 1 , to be connected through the resistor network
226- 1 , 226-2, 227, and 233 to the input transformer 1 5 S of
the radio transmitter. Throwing the "SEND-REC."
switch to "REC." position de-energizes relay 22S, switch­
ing the Telephone EE-S-A or EE-S-B and Loudspeaker
LS-I0-A, LS- IO-B or LS- I0-C to the output transformer
of the radio receiver, and energizes relay 412 of Rack
FT-244-A which in turn switches the antenna and plate
supply to the reciever circuits. Potentiometer 232 is the
"VOLUME" control which permits adjustment of the
radio receiver output.
( 3 ) Placing " L,9CAL-REMOTE" switch ( 224 ) , in
the "LOCAL" position connects the "COM." binding
c.
I
4-24
post ( 225-2 ) to the arm of "CHANNEL" control switch
224, permitting channel selection only at Control Box
BC- 1 3 12. Placing "LOCAL-REMOTE" Switch ( 223 )
in the "REMOTE" position disconnects the "CHAN­
NEL" control switch ( 224 ) of Control Box BC- 1 3 1 2
and connects it, through pin 2 o f receptacle 2 2 2 and by
Cord CD-95 1-A, to "CHANNEL" control switch ( 2 1 1 )
of Control Box BC- 1 3 14. This permits channel selec­
tion at the 500-foot control point ( Control Box BC1 3 14 ) instead of at Control Box BC- 1 3 12.
( 4 ) Placing the switch on any cotact of "CHAN­
NEL" control switch ( 224 ) , grounds the appropriate
contact of the ratchet motor coritrol circuits in Rack
FT-244-A. Thus the channel selector circuits controlled
by the ratchet motor are operated until the contact is
mechanically opened, and the desired channel is selected.
f.
CONTROL BOX BC- 1 3 14.
( 1 ) Socket 2 1 2 connects the "K," "COM.," and
"TEL:' lines and channel selector contacts to the
equivalent contacts in Control Box BC- 1 3 1 2 through
the 500.foot, eight-conductor Cord CP-S I0-A.
( 2 ) Switch 2 1 0 operates in the same manner as.
"SEND-REC:' switch ( 220 ) on Control Box BC- 1 3 1 2
which i s described i n paragraph 7.e. ( 2 ) , above. The
audio output is controlled by "VOLUME" control ( 2 1 5 ) .
( 3 ) "CHANNEL" control switch ( 2 1 1 ) will oper­
ate only when "LOCAL�REMOTE" switch ( 22 3 ) on
Control Box BC- 1 3 1 2 is in the "REMOTE" position.
The function of this switch is to select a radio channel
by operating relay 230- 1, 230-2, 2 30-l or 230-4 located
in Control Box BC- 1 3 12. The channel selector deter­
mines the relay which will be operated, and the relay
acts Hke a secondary switch selecting a radio channel
for Control Box BC1 3 14. The actual circuit for select­
ing the channel is not completed directly from Control
Box BC 1 3 14 because in some cases, the resistance of
the cable to and from Control Box BC- 1 3 14 may drop
the voltage to a potential which would not operate the
relays in Rack FT-244-A necessary to change channels.
g. CONTROL BOX BC 1 3 13.
( 1 ) Bindirig post "K," "COM," and "TEL." of
Control Box BC- 1 3 1 3 is connected to "K," "COM," and
"TEL:' binding posts to Control Box BC- 1 3 14 by means
of a three-wire telephone ( 2-mile maximum ) line.
( 2 ) The only two controls on Control Box BC1 3 1 3 are "SEND-REC." switch ( 200 ) which operates in
the same manner as "SEND-REC:' switch ( 220 ) on
Control Box BC- 1 3 1 2 and volume control 203. ( See
paragraph 7.e. ( 2 ) , above. )
8.
CONTROL C I RCU I T.
( 1 ) If channel "A" is selected the "A" contacts of
switch 224 or relay 230-4 are closed, permitting a flow
of current from the ' plus 1 3-volt supply through the
coils of relays 4 1 i� 1 and 41 1-2, the contacts of motor
positioning switch 427-A, switch 224 ( or 2 1 1 ) and the
contacts Of relay 130 to.:ground ( minus 1 3 volts ) .
tl.
FREQUENCY CHANGING OPERATION . .
R,vised
2
January
1 95 2
AN
1 6-40SC R624-2
VOLUME
�
C=
D=
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TR
�O�L'--i--�;�Ii:::;====:::;--1J�ll+-o.:j
R- I 0 2
1 0 .0 0 0 .1\.
:!: 2 0 '-
.
R-IOI
400.n.
I -WATT
!20�
-----'-­
10'
PHONE
TIPS
H-IOI
-' o ,
q
III
. C - I C ;'
-
I AMP. FUSE
F- IOI
+
-
IO
J
-::====��
__�
RUBBER COVERED
P O W E R CORD
:
1 2 . 6 Y.
2 2 0 V.
I I O V.
'-------<>--­
Loudspea ker LS- J O-A
Figure 4-22.
Circuit Diagram
I M E G .Il.
INPUT
g==c==-'...ro
l A MP.
I
tv. �i
�
1 1 7 V.
87P35
R-I
Circuit Diagram
C-I
. 0 1 M F.
± 20 'Y.
IOOO V.
VOLUME CONTROL
10,000 J'!. ± 20"4
VOICE
LS - I
COIL
!5 I I
PM
IMPEDANCE
SPEAKER APPR OX .
3 . 2 OHMS
J
C-2A
20 M F.
4 5 0 W. V.
JK34A
CO- 2 1 9
CORDAGE
I
I
I
-*-
Loudspeaker LS- J 0-8
Figure 4-23 .
-----'-­
10'
GND.
T-2
POWER
LM - I
INPUT
CO NNECTION
SW - I
O N - OFF·
TOGGLE
SWITCH
PLUG
VC IMPEDANCE
APPROX . 4 OHMS
INPUT CONNECTION
SPEC IAL
ADAPTER
PLUG
P - IDI
POLA R I Z E D
}
SPEAKER
20 MFO.
4 5 0 V.
r-----�-:
:
#,�;�
;�;�OI
9+ YOLTAGE
NOT TO EXCEED
300 V.
CO -219
CORDAGE
S- IOI
OFF-ON
TOGGLE SWITCH
PHONE
TIPS
Section I V
F i g u re s 4-22 - 4 -2 4
J
F-I
FUSE
l AM P .
RUBBER
COVERED
POWER
CORD
10'
Figure
Revised 27 May 1 949 �
PILOT LITE
6.3 V.
SW-2
TOGGLE SWITCH
FOR SUpPLY VOL TABE
4�24.
R-3
I MEG. �
I WATT
234 V.
1 1 7 V.
loudspeaker LS- J O-C
V-2
JAN- 6X5GT
Circuit D iagram
4-25
Secti o n s IV-V
P a ra g ra p h s 8 a ( 2 19-V- l a2&(31
AN 1 6-40S C R 62 4 - 2
(2) Relays 4 1 1 - 1 and 4 1 1-2 immediately operate.
When the contacts of relay 4 1 1-2 close, a potential of
13 volts is applied to ratchet motor 406, causing it to
rotate until positioning switch 427A opens, at which
time the transmitter and receiver channel "A" slides will
be completely engaged. The opening of contacts 427 A
breaks the circuit through relays 4 1 1 - 1 and 4 1 1-2,
stopping the motor instantly.
( 3 ) The operation of relay 4 1 1 - 1 may be disre­
garded when the equipment is in the "RECEIVE"
(normal stand by) condition, since relay 4 1 2 is already
energized by current flowing from the plus 1 3-volt sup­
ply, through one pair of con.tacts of relay 228 to ground.
However, if channel shifting were to start while trans­
mission was going on ( antenna relay 4 1 2 de-energized ) ,
current would flow from the plus 1 3-volt supply through
the coil of relay 4 1 2 and through relay 4 1 1 - 1 to ground,
thus . transferring the antenna relay 4 1 2 to the "RE­
CEIVE" position until channel shifting was completed.
b. TRANSMIT OPERATION.
( 1 ) When the equipment is in "RECEIVE" posi­
tion, the antenna relay 4 1 2 is operated by the current
from the plus 1 3-volt supply through its coil and one
pair of contacts on relay 228 to ground.
( 2 ) In its operated position, relay 3 1 2 connects the
antenna to Radio Receiver BC-624-A or BC-624-AM
and connects plus 300-volt to the r-f circuit of the re­
cei ver. When the "SEND-REC. " switch is on "SEND,"
relay 228 is operated and the circuit from the plus
1 3 -volt supply through relay 4 1 2 is broken, and relay
4 1 2 is de-energized. With the antenna relay in this
condition, the antenna is connected to the r-! output
terminal of Radio Transmitter BC-62 5-A or BC-62 5AM and a potential of plus 300-volt is transferred
to the plate circuit of the transmitter oscillatoJ." tube
JAN-6G6G (VT- 198-A) and second harmonic ampli­
fier tube JAN-832 (VT- 1 1 8 ) .
9 . L O U DS P E A K E R LS· ' O· A, LS. ' o· a A N D LS. ' O · C
Loudspeaker LS- l O-A, LS- I O-B or LS- I O-C contains a
permanent magnet speaker, a power supply for opera­
tion from 1 1 5 to 2 3 0 volts, 40 to 60 cycles a-c input,
and a two-watt amplifier for boosting audio-frequency
output. For rectification the power supply uses a tube
JAN-6X 5 GT ( VT- 1 26-B ) and for amplification a JAN1 2A6 ( VT-244 ) . ( See figs. 4-22, 4-23 and 4-24. )
SECTION Y
MAI NTENANCE
IMPORTANT
Periodic inspections prescribed herein repre­
sent minimum requirements. If, because of
local conditions, peculiarities of equipment,
or abnormal usage these inspections are found
insufficient to assure satisfactory operation of
equipment, local authorities should not hesi­
tate to increase their scope or frequency.
WARN I NG
,
This equipment employs high voltages which
are dangerous and may be fatal if contacted by
personnel. Use extreme caution when work­
ing with the equipment.
•
a.
DAILY I N SPECTION.
VISUAL INSPECTION.
( 1 ) Check that the antenna mast is secure.
( 2 ) Check for intermittent contacts by placing the
receiver in operation and subj ecting the major units
and associated plugs and cordage to jarring.
( 3 ) Check all plug and socket connections.
(4) Check all interconnecting cords for breakage.
( Note particularly the power and antenna cables. )
( 5 ) Power Unit PE-75-D for gasoline, oil, and
water.
4._ 2 6-5 - 0
b. OPERATIONAL INSPECTION.
( 1 ) Select - channels "A," "B," "C," and "0" on
one of the control boxes in sequence to check the opera­
tion of the ratchet motor and the shifter mechanism.
Repeat for each control box used on the installation.
( 2 ) Check with another station to check the modu­
lation of the transmitter.
( 3 ) Check the operation of the receiver by listen­
ing for noises.
(4) Check the telephones for proper operation.
2. WEEKLY I NSPECTION.
a.
INSPECTION OF ANTENNA MAST MA-7-A.
( 1 ) Check the security of mounting and condition
of all stays and anchors.
( 2 ) Check the antenna base cable connection for
corrosion and loose contact.
b. INSPECTION OF CONTROL BOXES BC1 1 75-A, BC- l 1 7 1 -A, BC- 1 1 76-A, BC- 1 3 I 2,
BC- 1 3 I4, AND BC- 1 3 1 3.
( 1 ) Remove the screws at the base of the control
box ,i n question and pull the bottom plate free.
( 2 ) Check relay contacts for fungus growth and
corrosion.
( 3 ) Check switches for satisfactory operation.
Revised 27
May 1949
Section V
I'aragra p h 2 b (4)-2(2)(b)
AN 1 6-40SCR624-2
RE C E I V E R C O VE R
RE TA I N I N G S CR E W 43 / - 3
T R A N S M I T T E R COVER
R E TA I N I N G S CR E W 43 1 - /
R E CE I V E R C O VER
HAN D L E
1401 - 3
DZ U S FA S TE NE R S ---,
T{?ANSMI T TE R C O VER
-------- S H O C K M OUN T
S H O C K M O UN T
1 401 - 2
fig ure 5 - 1 .
Transmitter - R e ceiver A s s e m bly-front Obliq u e View
(4) Visually inspect all connections for breaks,
fungus growth and corrosion.
( 5 ) Reassemble the control box taking care to
tighten the screws securely.
OF RACK FT-244-A.-This in­
c . INSPECTION
spection applies to racks in Radio Transmitter BC62 5-A or BC-62 5-AM, and in Radio Receiver BC624-A, BC-624-AM, or BC-624-C.
( 1 ) RACK INSPECTION.
(See figure 4-20.)
(a) Remove the six screws on the rack center
cover which are not recessed and the lock washers se­
curing the rack center cover. Remove the center cover.
(b) Blow the dust and dirt out with dry com­
pressed air. Avoid subj ecting the delicate parts, par­
ticularly the antenna changeover relay, to direct blasts.
( c) Inspect the mounting screws and electrical
connections on the antenna receptacle 416. (See fig. 5-1 .)
(d) Inspect the mounting and electrical connec­
tions on antenna relay 412. Clean and burnish 01
polish the relay contact points as directed in para­
graph 6c ( 8 ) (b), this section.
(e) Inspect the condition of the pins of re­
ceptacles 420 and 4 1 7.
(f) Inspect relays 4 1 1 - 1 and 41 1 -2 by pressing
the armature lightly until it stops. Then check the con­
tact points of the relay. Clean the contact points as
directed in paragraph 6c ( 8 ) (b), this section.
(g) Inspect the cable wiring for wear where it
goes through the center channel of the rack. At the
same time inspect the cable where it passes under the
receptacle and over the shifter mechanism shield.
( 2 ) RACK SHIFTER MECHANISM A N D
RATCHET MOTOR INSPECTION.-Stand the rack
on its end with the ratchet motor down and inSpect
the following parts for dirt, corrosion, and need of
lubrication: (For /(jcation of parts see fig. 5-12.)
(a) The receiver shifter actuating slides and
their respective tracks and spacers. (If relubrication is
necessary, refer to par. 6b, this se�. )
(b) The transmitter shifter actuating slides and
their respective tracks, spacers, and slide heads. (Re5-1
Section V
Paragra p h 2(2)(d-2e(S)
AN 1 6-40SCR624-2
fer to paragraph 6b, this section, if lubrication is
needed. )
( c) The motor arms ( refer to paragraph 6b, this
section, if lubrication is needed) .
(d) Each pair o f cross arms at each end and at
the pivoting point.
(e) The ratchet wheel of the motor. (To clean
the ratchet wheel, rotate the wheel by pressing and re­
pressing the pawl spring perch. Make sure the ratchet
wheel is left in a position where all the shifter actuating
slides are disengaged. )
(f) The pawl and pawl stop o f the motor.
(g) The hinge assembly on the motor.
(h) The shifter slides ( for broken or damaged
cams and springs) .
( 3 ) MOTOR INTERRUPTER CONTACTS IN­
SPECTION.-Inspect the motor interrupter contacts.
If the contacts need repair other than cleaning, replace
the rack assembly. (For location of parts see fig. 5-12.)
d. INSPECTION OF THE RECEIVER.
( 1 ) VACUUM TUBES.
(a) Inspect the vacuum tubes for signs of oxida­
tion and their sockets for cracks.
(b) If the tubes require replacement, refer to
paragraph 5, this section.
N ote
Use all tubes of a given type supplied with the
equipment before employing tubes from gen­
eral stock. Remove the vacuum tubes from
their sockets by pulling nearly straight up.
Install the tubes by pushing nearly straight
down. If necessary, rock tubes slightly.
( 2 ) MECHANICAL.-Place the receiver so that
slides and tuning controls are up and rotate the two
turning controls (see fig. 4-9) making certain each
turns easily and does not bind. Inspect the following:
(a) The four shifter mounting screws ( for se­
curity) .
(b) The mounting nuts on the "AUDIO" and
"RELAY" controls (see fig. 4-9). If they are loose,
tighten and seal them with glyptal.
( c) The mounting screws of all plugs and re­
ceptacles.
(d) The four positioning clips, dip springs, and
the four cam assemblies on each stack assembly. To
check, push each shifter in with a finger until it seats
firmly. Release quickly. Unless a cam or positioning
dip or clip spring is defective, the slide will return
. to the released position and the tuning controls will
rotate to their respective settings as each slide is de­
pressed.
(e) The bearing surfaces of the shifter slides.
Clean them with solvent PS-661 or carbon tetrachloride.
If relubrication is necessary, see paragraph 6b, this
section.
5-2
(f) The mounting of the r-f and oscillator assem­
bly for security. ( Be careful not to disturb the settings
of the coils and trimmer capacitors. )
(g) The mounting nuts o n the crystal board.
(h) The various parts mounted on the chassis
( for security) .
(i) The three mounting screws o n the end of the
chassis holding the r-f and oscillator assembly ( for se­
curity) . (See fig. 4-9.)
(i) The mounting screws and nuts of each com­
ponent part accessible from the bottom of the chassis
( for security).
( 3 ) ELECTRICAL.-Inspect for the following:
(a) Evidence of wearing of cables in the chassis.
(b) Loose solder joints and terminal board con­
nections.
(c) Frayed leads or broken strands of wire.
(d) Nearly shorted connection.
e. INSPECTION OF THE TRANSMITTER.
( 1 ) Place the transmitter with the tuning con­
trols up.
( 2 ) Remove the power amplifier shield, located on
the end of the chassis, after loosening the four Dzus
fasteners. (See fig. 4-5.)
( 3 ) Inspect the vacuum tubes for tightness in the
sockets and tight fitting grid caps. Check all tubes
except tube JAN-832 in a tube checker. ( Instructions
for testing tube JAN-832 appear later in this section.)
If tubes require replacement, see paragraph 5 a ( I ) , this
section.
N ote
Use all tubes of a given type supplied with the
equipment before employing tubes from gen­
eral stock.
(4) Check in the power amplifier section for se­
curity of parts and wiring, paying particular attention
to the mechanical condition of the antenna coupling
inductor 122 (see figs. 4-5 and 4-6) and flexible plate
leads to tube JAN-832.
( 5 ) Replace the power amplifier shield making
certain that the mycalex strip 163 (see fig. 4-5) rests
securely between the plate pins on tube JAN-832 and is
exerting a downward pressure.
(6) Inspect for security of the four frequency
shifter mounting screws.
( 7 ) Rotate each of four tuning controls making
certain that each turns easily.
( 8 ) Inspect the mounting nut on the "GAIN"
control 1 2 5 . (See fig. 4-1 .) If it is loose, tighten and
seal it with glyptal.
N ote
This "GAIN" control has been eliminated on
later productions of the transmitter.
Sectio n V
P a ra g ra p h s 2e(9)-3&
AN 1 6- 40SCR624-2
( 9 ) Rotate the knob of the "METER SWITCH"
1 65 (see fig. 4-1 ) trom position 1 to 6 and check for
normal rotation and locking.
Reassemble in Case CS-so-A or Case CS-SO-C and con­
nect the plugs to the rack sockets.
( 10) Inspect the four positioning clips, the clip
springs, and the four cam assemblies by pushing each
shifter slide in with the fingers until it seats firmly. Re­
lease quickly. If the cams, positioning clips and clip
springs are not defective, the slide will return to the
released position, and the tuning controls will rotate to
their respective settings as each slide is depressed.
( 1 ) Install crystals corresponding to the assigned
channel frequencies in the transmitter crystal sockets.
(See fig. 4-1.) Tune the transmitter according to the
directions in paragraphs 9a and b, this section.
( 2 ) Install crystals corresponding to the assigned
frequencies in the crystal sockets of the receiver. Tune
the receiver according to the directions given in para­
graph 9c, this section.
( 1 1 ) Inspect the bearing surface of the shifter
slides and clean with PS-661 solvent or carbon tetra­
chloride. If lubrication is necessary, see paragraph 6b,
this section.
( 1 2 ) Place the transmitter on one side, then on the
other side and finally up on one end, and, in each
position, inspect for security .of the component parts
which are accessible in each position.
( 1 3) Reassemble the receiver and transmitter with
the rack. Make certain, before tightening the mount­
ing screws of the receiver and transmitter, that their
respective actuating slides are approximately 1 /32-inch
from the slide assemblies when in the released position.
TABLE 5 - 1 .
TROUBLE LOCATION
f. TRANSMITTER AND RECEIVER TUNING.
3.
TROU BLE LOCATION.
a. TRANSMITTER-RECEIVER ASSEMBLY. - Be­
fore removing any component from Radio Set SCR624-A, determine the cause of failure and isolate the
particular faulty circuit or component of the equipment.
Look for the simple causes of trouble first. Once the
identity of the defective unit has been established be­
yond reasonable doubt, remove and repair it or replace
it with a good unit.
The following list of troubles and probable causes
will assist in locating and remedying some of the more
common faults in the radio set.
CHART
FOR
RADIO
SET
SCR·624 .
Symptom
Probable Cause
Receiver operates properly, but no transmitter out­
put on any channel.
Transmitter not tuned properly. No crystal in socket. Defective antenna relay
4 12. Locking relay 4 1 1- 1 jammed in operative position. Ground on pin 17,
in 1S-pin socket 417 on Rack FT-244-A, or associated wiring connecting to
that pin. Defective transmitter.
Transmitter operates properly but receiver dead or
only rectifier ripple audible in headset.
Receiver not tuned properly. No crystal in socket. Receiver "AUDIO" or
"RELAY" controls rotated fully counterclockwise. Defective receiver. De­
fective wiring in audio output circuit (pin 3 in 1S-pin socket 4 1 7 on Rack
FT-244-A) . Defective microphone-headset jack or plug. Defective antenna
relay 4 1 2 or associated control wiring.
Audible howl in head set; also modulation present
on transmitter carrier.
Water or dirt between terminals or contacts of microphone jack.
Channel selecting mechanism in Rack FT-244-A is
operated when any channel is selected but one or
tv. ;) channels are inoperative for both transmit­
ting and receiving.
Defective or misadjusted motor positioning switch 427 in Rack FT-244-A, caus­
ing overtravel of rachet motor and subsequent release of receiver and trans­
mitter channel-selecting slides. This may also be due to sluggish relay 4 1 1-2..
Transmitter and receiver both apparently properly
tuned, but communication is either very poor or
impossible.
Defective antenna relay 4 12 in Rack FT-244-A. Open transmission line.
fective connection between antenna Socket 50- 1 5 3 and antenna mast.
Receiver output will not squelch properly when
"RELAY" control in receiver is rotated counter­
clockwise, or set is very noisy when vibrated
after output is squelched.
Coil of squelch relay 246 if receiver is open, or relay is out of adjustment.
Contacts of relay may be dirty.
Transmitter or receiver will not stay in tune.
Tuning control locknuts not sufficiently tightened. Defective coupling between
tuning control and variable capdcitor. Loose 'set screws fastening couplings
to tuning control shaft or variable capacitor shaft. Broken mycalex or ceramic
shaft in receiver gang capacitor.
De­
b. RADIO RECEIVER BC-624-A, BC-624-AM, or
BC-624-C.-The following chart gives the possible
causes of trouble in the radio receiver.
5-3
.
Secti o n V
Paragra p h 3 c-3d
AN 1 6-40S C R 62 4 - 2
TABLE 5 - 2 .
TROU BLE LOCATION C HART F O R THE R A D I O RECEIVER.
Symptom
Probable Cause
Set dead and no microphone sidetone audible in
headset.
Defective tube ]AN- 12C8 (VT- 169) or tube JAN- 12J5 (VT- 1 3 5 ) . Defective
resistor, capacitor, transformer or wiring associated with these tubes. No
crystal in sock;et.
Set dead but sidetone is audible in headset.
Defective tube JAN- 12SG7 (VT-209) . Defective resistor, capacitor or wiring
associated with these tubes. Check alignment of i-f transformers (see para­
graph 9.,c.) .
Set operates on extremely strong signals.
Defective tubes JAN-9002 (VT-202 ) , JAN-9003 (VT-203), o r JAN- 12AH7GT
(VT-207). Defective resistor, capacitor or wiring associated with these tubes.
Check alignment of r·f and oscillator assembly. (See paragraph 9.,d.)
Set will not remain in tune although locknuts are
tight.
Check all variable-capacitor coupling set screws and if found tight, examine the
couplings themselves for slippage. Examine variable capacitors for cracked
rotor shaft or evidence of slippage between the rotor plates and the front
end of the shaft.
Impossible to obtain proper adjustment of squelch
relay by manipulation of " RELAY" control.
Check contacts of relay 246 for dirt (use a contact burnisher or draw a piece of
paper through the contacts when closed ) . If this relay does not open and
close when the "RELAY" control is varied from maximum to minimum
rotation, adjust the armature spring tension so that the relay will operate
when the "RELAY" control is varied through a point about one-third of the
way down from the maximum clockwise rotation stop. This adjustment should
be made with the transmitter plugged into the rack, but with no antenna or
transmission line connected to Socket SO- I S 3. If relay still does not operate
properly, try replacing tube JAN- 1 2AH7GT (VT-207) ; check relay coil for
open or short circuit and check all resistors and capacitors associated with
this circuit. See paragraph 9.,c., this section, for adjustment of squelch relay.
c. RADIO TRANSMITTER BC-62 5-A or B C-625 AM.-In addition to making the checks suggested in
paragraph 2 e., this section, inspect the following:
( 1 ) Capacitors for shorts, intermittent shorts, or
opens.
( 2 ) Resistors fOor opens or wrong values.
(3 ) Faulty connections or pieces .Oo f solder or wire
which might cause short circuits.
d. RECTIFIER RA-62-B or RA-62-C.-The follow­
ing chart gives the troubles and causes which may occur
in the rectifier.
Trouble
Power does not reach rectifier.
Probable Cause
Faulty plugs or contacts in a-c power line cord. Broken wiring in this cord.
Poor contacts in voltage selector switch. Burned out fuses. Defective
"OFF-ON" switch.
Low output on 105, 1 1 5 and 1 2 5 voltage taps and
no output on 2 10, 2 30 and 250 voltage taps.
One of fuses in either primary of power transformer burned out. Broken contacts
or defective wiring in any circuit of either primary of power transformer.
Tubes JAN-5U4G (VT-244) do not light.
Defective wiring or connections between tubes and terminals 9 and 10 of power
transformer secondary. Defective tube.
Tube JAN-6X5GT (VT- 1 26B) does not light.
Defective wiring or connections between tube and terminals 14 and 15 of power
transformer secondary. Defective tube.
Tubes JAN 5U4G (VT-244) light but do not func­
tion.
Defective wiring or connections between plates of tube and terminals 1 1 and
13 of power transformer secondary. Defective wiring between terminal 9 of
power transformer secondary and pin 2 in doc output socket. Defective relay
or associated control wiring in plus 3 10 volt line. Defective capacitor or
choke in the filter of the plus 3 10 volt circuit.
Tube JAN-6X5GT (VT- 126B) lights but does not
function.
Defective wiring or connections between plate terminals of tube and terminals
16 and 17 of power transformer secondary. Defective wiring or components
of filter in the cathode circuit. Defective tube.
Voltage at plus 1 3.0-volts terminal not constant.
Defective wiring or connection in voltage regulator.
properly adjusted.
5 -4
Voltage regulator not
Secti o n V
AN 1 6 - 40S C R 6 2 4 - 2
e . CONTROL
BOXES BC- 1 1 75-A, BC- 1 3 1 2 , Be1 1 7 l -A, BC- 1 3 14, BC- 1 1 76-A, or BC- 1 3 1 3.-The loca­
tion of trouble in these control boxes is simple and can
often be accomplished by checking the following:
( 1 ) The binding posts and switch contacts for
security.
( 2 ) The switch contacts for cleanliness.
( 3 ) All the units for broken wires.
(4) Interconnecting cords for breakage.
( 4 ) Connect the proper plugs to the sockets on
the rack and to a proper voltage source of supply.
Connect antenna AN-94-A, AN-94-B, AN-94-C or AN1 88 to the antenna socket on the rack.
( 5 ) Turn the equipment on by pressing any chan­
nel button on the radio control box.
( 6 ) Using Test Set 1 - 5 6- ( * ) or equivalent (meter
sensitivity of 1 000 ohms per volt ) , make the tube
socket voltage measurements listed in the chart below.
( 7 ) Make all measurements to chassis ground and '
on the 500-volt scale unless otherwise specified. Fol­
low the additional suggestions in the voltage diagram
4. TROUBLE SHOOT I N G-DETA ILED.
a.
TRANSMITTER TUBE SOCKET VOLTAGE
MEASUREMENT S .
( 1 ) Loosen the Dzus fasteners at the top front and
top rear of Case CS-80-A or CS-80-C. Grasp the rack
by the recessed handles and remove it, together with the
transmitter and receiver, from the case.
( 2 ) Loosen the Dzus fasteners that hold the top
covers to the center of the rack and take out the four
screws that hold the top covers at the sides . Take off
the covers.
( 3 ) Place the a ;sembly on its side on a test bench,
so that the transmitter vacuum tube sockets are acces­
sible . .
TABLE
5 -3 .
P a ra g ra p h s 3 e-4b l l )
(fig. 5- 2) .
( 8 ) If the voltages vary appreciably (more than
plus or minus 1 5 percent from the values given in the
chart below ) , make a further examination of the com­
ponents associated with the circuit.
Note
The following readings are taken with dyna­
motor unit outputs of exactly plus 300 volts,
minus 1 50 volts, and plus 13 volts. The out­
put of Dynamotor Unit PE-94-A is slightly
higher so the voltage readings for the plates
and screens may be slightly higher.
TRANSMITTER TUBE SOCKET VOLTAGE MEASU REMENTS.
Volts
Tube
(AI'my Type)
Function
Plate
Screen
GRID
GI Ul G1 U2
JAN·832 *
(VT- 1 l 8)
2nd harmonic
amplifier
300
1 50
-57
-80
JAN-832
(VT· 1 l 8 )
Power
amplifier
283
160
-52
-52
JAN·6G6G
(VT· 198·A)
Oscillator
300
157
·29
JAN· 12A6
(VT- 1 34)
1 st harmonic
amplifier
300
280
-40
JAN·6SS7
(VT· 199)
Speech
amplifier
286
40
Varieties
JAN- 12A6
(VT· 1 34)
Modulator
290
265
· 13.5
JAN· 12A6
(VT· 1 34)
Modulator
290
265
· 1 3.5
JAN·6SS7 * *
R-F indicator
diode
- 2 .4
2 .4
* Tubes VT· 1 l 5 are push-pull amplifiers. The voltage on the
first grid of the second harmonic amplifier varies from about
minus 40 to minus 87 volts and . the second grid varies from
about minus 40 to minus 1 0 5 volts.
h. RECEIVER TUBE SOCKET VOLTAGE
MEASUREMENTS.
( 1 ) After making the transmitter tube socket volt­
age measurements, press channel release button 426 to
release the frequency shifter slides.
Cathode
o
o
40
2.2
o
o
- ·2.4
o
Heater
Heater
12.5
6.4
12.5
6.4
12.5
6.5
12.5
0
6.5
0
12.5
0
12.5
0
6.5
0
Suppressor
0.75
2.2
·2.4
* * Not installed in later models.
( Identified by painted bar
next to "METER SWITCH" position "4") or in Radio Trans·
mitter BC-62 5·AM.
CAUTION
Damage to equipment will result if the shifter
slides are not released prior to removing the
transmitter from the rack.
* Refers to any issue.
5-5
"TI
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YT-134
1'100l/L A TOR
1'100llUl TOR
CONDITIONS OF MEASUReHeN T
VOLTMETER SENSITI VI T Y - IOOO OHI'1S PER VOL T
INPUT TO DYNAMOTOR - Z8 VOL TS
FREQUENCY - /JO MCS
poweR OUTPUT - IZ, 7S WA TTts
D YNAMOTOR OUTPfJTS : .. JOO II. -140 11. ..1311.
100 % HODULATION
"GAIN " CONTROL rULLY CLOCKWISE. (THIS CONTROL
nEL £T£D ON LATER TRANSMITTERS.)
ClRCIII T
II MEI/SURED T1/RII 25 MIf CHOKE.
l/1 Ml451111l0 RT R£71.II1N END OF
TOP YIEW OF
TUBE y T-1I8
2ND.
YT-IIB
HA RM
RMPLlFI£R
IS
Figure 5 - 2 .
Tra n s mitter T u b e Socket L a y o u t a n d Voltag e s
GIIIO
CONNEC TION ro roSE.
E-I'TERIYI9L
C()HIVECT7()/Y.
Tll 'METEIl .5lt//1(# "CW .PO.JITION4
eo TTOM YlEIYS OF roBE SOCIUT.s
RRE SHOJtlH.
n
::a
0�
.110
I
�
Secti o n V
Paragra p h 4&(2'-4&( 1 1 '
AN 1 6-40S CR624-2
( 2 ) Turn the equipment off by pushing the
button on the radio control box.
"OFF"
( 7 ) Rotate the receiver "AUDIO" and "RELAY"
controls to their extreme clockwise positions.
( 8 ) Press any one of the channel selector buttons
on the control box.
,
( 9 ) Using Test Set 1- 1 5 6- ( * ) or equivalent, ( sensi­
tivity of 1 000 ohms-per-volt) make the tube socket
voltage measurements listed in the chart below.
( 10) Use the 500-volt scale and make the measure­
ments to chassis ground unless otherwise specified.
Follow the additional directions given in the voltage
diagram, figure �-3.
( 1 1 ) If the voltages vary appreciably (more than
plus or minus 1 5 percent) from the values given in the
chart below, make a further examination of the com­
ponents of the associated circuit.
( 3 ) Remove the four red mounting screws fasten­
ing the transmitter to the rack.
(4) Lift the transmitter side of the rack slightly
while pressing the top of the transmitter down with
the thumbs. Lift the rack, together with the receiver,
away from the transmitter.
( 5 ) Block the blocking relay 4 1 1 - 1 in the ener­
gized position.
( 6 ) Connect a jumper from terminal 4 of socket
4 1 8- 1 to any convenient ground point on the rack
chassis.
TABLE 5 -4 A .
R A D I O RECEIVER BC - 6 2 4 - A O R BC-624 -AM T U B E SOCKET VOLTAGE MEASU REMENTS.
VOLTS
Function
Tube (Army) Type
Plate
Suppressor
Screen
Grid
Cathode
o
2.7
6.5
2.3
12.9
2.5
4.5
1.8
1 3.0
JAN-9003 (VT-203)
R-F amplifier
255
2.7
80
JAN-9003 (VT-203)
Mixer
295
2.3
42
2.5
75
JAN-9003 (VT-203)
JAN-9002 (VT-202)
JAN- 12SG7 (VT-209)
JAN- 12SG7 (VT-209)
* tJAN- 12SG7 (VT-209)
Harmonic amplifier
260
Harmonic generator
1 st I-F
1 80
290
1.8
70
2nd I-F
285
1 .4
65
3rd I-F
280
JAN- 12C8 (VT- 169)
Detector
J AN- 12J5GT (VT- 1 3 5 ) 2nd A - F amplifier
JAN- 1 2AH7GT
Oscillator squelch
UAN- 1 2 SG7 (VT-209)
UAN- 12H6 (VT-2 14)
3rd I-F
Noise limiter AVC
135
3
75
8.5
295
260
290
308
20
5
200
o
o
o
o
o
o
o
4
o
o
o
Heater
Heater
0
6.5
6.8
0
0
0
6.9
1 3.0
1 3.0
1.4
3
0
1 3.0
1 3.0
8.5
10.5
12.0
27
5
0.6
1 3.0
1 3.0
0
0
0
1 3.0
0
1 3.0
0
* Radio Receiver BC-624-A only.
t Note that this tube is a duplex diode-pentode.
:j: Radio Receiver BC-624-AM only.
TABLE 5 -4 B.
RADIO RECEIVER BC- 6 2 4 - C-TU B E SOCKET VOLTAGE MEASU REMENTS.
Tube
JAN-900 3
VT-203
JAN-9003
VT-203
Function
R-f amplifier
Mixer
Pin
Number
Element
1
G,
2
3
4
5
6
7
E
H
K
P
G2
K-G,
1
G,
2
3
4
5
6
7
H
H
P
G2
K-G,
K
Scale Used
l O-volt
1 0-volt
lO-volt
Volts
(1 000 OhmsPer-Unit)
0
0
+3.0
0
+6.5
+255.
+90.
+3.
+3 .0
0
+7
+280
+ lOO
+ 3. 1
0
l O-volt
10-volt
50-volt
2 sO-volt
l O-volt
Volts:j:
(20000* OhmsPer-Unit)
+3
+6.6
+ 1 3.
+285.
+50.
+3.
0
+3
+6.5
+13
3 10
+60
+3
JThe input was +320V and + 1 3V.
*
These measurements were taken with a Weston 772 voltmeter.
5 -7
Section V
P a r a g ra p h 4b-Ta b l e 5 -4 B-I C o n t ' d l
TABLE 5 -4 B .
Tube
JAN-9003
VT-203
JAN-9002
VT-202
JAN- 12SG7
VT-209
JAN- 12SG7
VT-209
JAN- 12SG7
VT-209
JAN- 12AH7GT
VT-207
JAN- 12C8
VT- 169
A N 1 6 -405 C R 6 2 4 - 2
RA DIO RECEIVER BC-624 -C-TU BE SOCKET VOLTA GE MEASU REMENTS- ( C o nt ' d ) .
Function
Pin
Number
2
3
4
5
6
7
Harmonic generator
2
3
4
5
6
7
2
3
4
5
6
7
8
2
3
4
5
6
7
8
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
2
3
4
5
6
7
8
These measurements were taken with a Weston 772 voltmeter.
5-8
K
H
H
P
G
K
2 50-volt
l O-volt
l O-volt
10-volt
l O-volt
H
K-G"
G,
K-G,
G2
H
P
l O-volt
10-volt
lO-volt
2 50-volt
50-volt
H
K-G,
G,
K-G,
G2
H
P
l O-volt
lO-volt
10-volt
2 50-volt
50-volt
S
Third i-f amplifier
:j:The input was + 320V and + 1 3V.
*
P
lO-volt
10-volt
50-volt
S
Second i-f amplifier
audio
K
H
H
P
G,
K-G,
S
First i-f amplifier
A VC and second
Scale lIsed
G,
Harmonic amplifier
A VC delay and first
audio
Elem ent
H
K-G,
G,
K-G,
G,
H
P
1 0-volt
l O-volt
2 5 0-volt
50-volt
Volts
(1 000 OhmsPer-llnit)
Volts:!:
(20000* OhmsPer-llnit)
0
0
+2.5
+6.5
+ 1 3.
+250.
+85.
+2.5
+2�9
+7.0
+ 1 3.0
+280
+90
+2.9
+ 1 85.
+200
+4.5
0
+6.5
+ 185.
0
+4.5
+5.2
0
+7.0
+200
0
+4. 5
0
0
0
+ 1 .8
+.02
+ 1 .8
+65.
+ 1 3.
+275.
0
+ 1 .9
+.2
+ 1 .9
+75
+13
+295
0
0
0
+ 1 .3
+.02
+ 1.3
+60.
+ 1 3.
+27 5 .
0
+ 1.3
.2
+ 1.3
+75
+13
+290
0
0
0
+2.6
0
+2.6
+ 155.
+ 1 3.
+265.
0
+3.0
0
+3.0
+ 16 5
+13
+280
G,
1 0-volt
+0.2
+.5
K,
p,
K2
G2
P2
H
H
lO-volt
lO-volt
50-volt
10-volt
50-volt
+0.7
+0.2
+32.
+0.2
+43.
0
+ 1 3.
+ 1 .2 5
+.5
+42
+.6
+50
0
+13
S
0
0
H
P
P r>'
P D'
G,
H
K
0
+4 5 .
+7.
+7.
+30.
+ 1 3.
+ 1 6.
0
+60
+ 19
+ 19
+3 0
+13
+20
50-volt
50-volt
5 0-volt
2 50-volt
50-volt
50-volt
AN
TABLE 5 -4 B.
Section V
Paragra p h 4 c-4 d 5 )
1 6-40S C R624-2
RADIO REC EIVER BC-624 -C-TUBE SOCKET VOLTAGE MEASUREMENTS- (Cont' d ) •
Pin
Number
Function
Tube
Volts
(1 000 OhmsPer-Unit)
0
S
Third audio
JAN- 12A6
VT- 1 34
Scale Used
Element
H
P
G,
G,
No connection
H
K
2
3
4
5
6
7
8
50-volt
50-volt
+ 1 3.
+290.
+290.
0
No connection
0
+ 16.
Oscillator and
audio squelch
JAN- 12H6
VT-2 14
Detector and noise
limiter
K,
p,
K,
G2
p,
H
H
2
3
4
5
6
7
8
50-volt
1 0-volt
50-volt
+ 17.
+ 1 .0
+ 12 * *
0**
+240 * *
0
+13
+13
+300
+305
0
0
+ 19
p.
H
K,
p,
No connection
H
K,
+ 18
28
+ 12 . 5 * *
0**
280 * *
0
+13
0
0
50-volt
l O-volt
l o-volt
l O-volt
+ 1 3.
+0. 3
+0.4
+0.3
+13
+ 1 .0
+ 1.'()
+ 1 .0
l O-volt
0
+0.3
0
+1.0
S
2
3
4
5
6
7
8
0
+.125 ,
G,
JAN- 12AH7G7
VT-207
Volts:!:
(20000* OhmsPer-Unit)
:j:The input was + 320V and + 1 3V.
" These measurements were taken with a Weston ' 772 voltmeter.
* " Depress channel slide.
c.
TRANSMITTER CONTINUITY AND
RESISTANCE MEASUREMENTS.
( 2 ) Disconnect the equipment from the supply
source.
( 3 ) Rotate the transmitter "GAIN" control to its
extreme clockwise position.
(4) Leave all the vacuum tubes in their sockets
unless otherwise specified.
( 5 ) Use Test Set 1-56- ( * ) or equivalent to make
the resistance measurements listed in the following
chart.
N ote
The following measurements are for Radio
Transmitter BC-62 5 -A and BC-62 5-AM.
(Measurements pertaining to relay 1 30 will
not apply to Radio Transmitter BC-62 5-AM
since that relay has been removed from that
model.)
N ote
( 1 ) After making the receiver tube socket volt­
age measurements, turn the equipment off by turning
the rectifier "ON-OFF" switch to "OFF."
TABLE
From
TRANSMITTER
5-5.
To
1 2 3- 1 , Term, 4
1 2 3· 1, Term. 5
Ground
1 2 3-2, Term. 3
Ground
Ground
CONTI NU ITY
Control
Positions
If Not
Normal
Ohmeter
Scale
Used
R
Relay 1 30
dosed
x
R
x
R
x
Deviations in resistance greater than plus or
minus 1 0 percent should be investigated.
" Refers to any issue.
AND
RESISTANCE MEASUREMENTS.
Resistance
(Ohms)
Probable Cause of Incorrect Reading
1000
Open
'
Dirty or shorted contacts on relay 1 30.
1 000
Open
Same as above.
1000
Open
Shorted capacitor 102-5, 102-7, 102- 1 1 , 106, 107- 1,
1 08-2, III or 1 1 3.
5 -9
." '"
-'
CD
«A "
C :1'.
"
CD 0
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..
o
UI
I
'f' <
Col
o
NOTC '
I ' 5 VO/.T ",CALC _
Jl - 2 5 VOL.T SCAL. ( .
II! • Z 50 VOLT S C AU •
o o
(Q)
O �+IJ.O II
VT1.i�3f!i{'-MTOR
0 0
o
o
O � " 7 �O
FRON T VEW OFRCCEIVER CHASSIS
�Z44-1
�
� l44-4
W
VT-ZOZ HARM GEN
YT-2tB RFANP.
VT- 203 HARM. AMP
/17-203 NIKER
� Z44-3
W
�Z44-Z
o
These m e a s u re m e nts a pply to Radio Receiver B C-624-AM
except for c h a n g e s in the third I-F volta g e s , and a d dition
of tube JAN- 1 2 H 6 . See Ta ble 5-4A.
Fig ure 5-3.
�
Z44-1
Z44 - 4
+2. 7 1
+'� 5
If
"- . 6.S·
VT-Z03 R F AMP.
�
610 "
Z44 -Z
o
I . Z.l
+4Z
244 -3
. ."
.z.) ,
V T-ZO:!J HI4RM. AMP.
lO O O, N . 6. 5 .'2.,11
VIEW OF HI(jH FREqllE'NCY
Radio Receiver BC-624-A or BC-624-AM-Tu&e Socket layout and Voltages
J
�
n
:;III
0..
J
�
�
+ 2 "S
V T- ZO :!J MIXER
BOTTOM
•
Z
..
0-
TIIIJE SOCKET'S
TABLE
5-5.
From
1 2 3·2,
12 3·2,
12 3·2,
1 2 3·2,
Term
Term.
Term.
Term.
4
5
6
7
AN 1 6-40SCR624-2
Section V
Paragra p h 4c(5)-Ta ble 5-5-(Cont'd)
TRANSMITTER CONTI NUITY AND RESISTANCE MEASU REMENTS
To
Ground
Ground
Ground
Ground
Control
Positions
If Not
Normal
Relay 1 3 1
closed
Ohmeter
Scale
Used
Rx
Rx
Rx
Rx
1000
1 000
1000
1000
Resistance
(Ohms)
(Cont' d ) .
Probable Cause of Incorrect Reading
Open
Open
Open
Open
Shorted capacitor 102· 1, 102·2, or 105·4.
Shorted capacitor 102· 15.
Shorted capacitor 102· 14.
Dirty or shorted contacts on relay 1 3 1 .
R x 1000
50,000
1 69· 1 , Pin 1 (jet. pt.
1 04 and 1 50)
Same as above
1 69· 1 , Pin 4
169· 1 , Pin 5
Ground
T. B. 9, Term. 2
Ground
Ground
R x 1000
R x 1000
R x 1000
60,000
Open
50,000
169·2, Pin 4
Ground
R x 1000
Open
1 70· 1, Pin 3
1 70·2, Pin 3
169·5, Term. 6
1 69·5, Term. 8
1 69·3, (outside mod·
ulator) Pin 3
169·3, Pin 4
1 69·4 (inside modula·
tor) Pin 3
1 69·4, Pin 3
Ground
Ground
Ground
Ground
Ground
Rx
Rx
Rx
Rx
Rx
1000
1000
1000
1000
1 000
Open
Open
Open
Open
Open
Defective capacitor 102·3, 104, 102 · 1 2 o r 102· 1 3,
109· 1, 109·2:
Same as above.
Shorted capacitor 102· 1 , 102·2, or 105·4.
Defective crystal switch 156 or reactor 128· 1 ;
wrong value on resistor 1 5 1· 1 .
Shorted capacitor 102·5, 102·7, 102· 1 1, 106, 107· 1,
108·2, 1 1 1 or 1 13.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Ground
Ground
R x 1000
R x 1 000
Open
Open
Same as above.
Same as above.
R x 1000
265,000
Wrong value or open on resistor 140·2 or 140·3.
T. B. 8, Term. 9
T. B. 8, Term. 10
T. B. 7, Terms.
10, 1 1
Ground
Ground
R x l000
R x 1000
Open
Open
1 2 3· 1 , Term. 3
1 2 3·2, Term. 7
R x 1000
Open
Shorted capacitor 102· 1, 102·2, or 105·4.
Shorted capacitor 1025, 102·7, 102· 1 1, 106, 107· 1,
108·2, 1 1 1 or 1 13.
Dirty or shorted contacts on relay 1 6 1 .
1 2 3·2, Term.
Ground
R x 1000
20,000
169·2, Pin 4
1 7 0· 1 , Pin 2
T. B. I, Term.
Ground
R x 1000
R x 1000
5000
3 1 ,000
Same as above
T. B. 8,
Term. 1 1
R x 1000
26,000
1 70· 1 , Pin 3
1 70· 1, Pin 6
160, Term. 5
Ground
R x 1000
R x 1000
54,000
3 1 ,000
1 70· 1, Pin 6
R x 1000
26,000
1 70·2, Pin 2
T. B. 8,
Term 1 1
Ground
R x 1000
6000
1 70·2, Pin 3
1 70·2, Pin 6
160, Term. 5
Ground
R x 1000
R x 1000
2 1,000
6000
169·6, Pin 3
Ground
R x 1000
7000
169·6, Pin 3
R x 1000
5000
169·5, Pin 4
T. B. 8,
Term. 12
1 58, Term. 5
Defective reactor 127·3 or 127·4; open resistor 148
Of 146; shorted capacitor 102·3, 102· 1 2 or 102 · 1 3.
Defective resistor, 1 33· 1 or 1 3 3·2.
Defective reactor 127·3 or 127·4; open resistor 148
or 146; shorted capacitor 102·3, 102· 12 or 102· 1 3.
Shorted capacitor 105·2 ; defective resistor 154·3
or 1 5 3·2.
Same as above.
R x 1000
12,000
Defective resistor 1 5 3·4; dirty contacts on relay 1 3 1 .
169·5, Pin 4
Ground
6500
Defective resistor 1 5 3·4 or 142.
169·3, Pin 4
T. B. 7, Term. 4
5000
Defective resistor 1 54·2.
Relay 1 6 1
contacts
open
Relay
131
closed
Relay
131
closed
R x 1000
Defective resistor 146, 147, 1 52·3, .4, 109·5 o r 145 ;
shorted capacitor 102·12 or 102· 1 3, 102·3.
Defective resistor 1 54· 1 .
Open in reactor 127· 1 o r 127·2 ; shorted capacitor
102·8 or 102·9 ; open resistor 1 32· 1, ·2, or 146.
Deftctive resistor 148.
Defective resistor 1 52·2.
Open in reactor 127·1 or 127·2 ; shorted capacitor
102-8 or 102·9; open resistor 1 32· 1, ·2, or 146.
Defective resistor 148.
5-1 1
Secti o n V
Paragra p h 4c(5)-Ta b l e 5 - 5-I Cont'd '
TABLE
5 :� .
AN 1 6- 405 C R 62 4 - 2
TRANSMITTER CONTINU ITY A N D RESISTA N C E MEASUREMENTS
Control
Positions
If Not
Normal
To
From
Ohmeter
Scale
Used
169-3, Pin 5
Ground
169-4, Pin 5
1 2 3- 1, Term. 6
Ground
1 2 3-2, Term. 2
R x 1 000
R x 1000
R x 10
1 2 3-2, Term. 2
Ground
R x 10
169- 1, Pin 1
169-2, Pin 5
169-2, Pin 8
169-5, Pin 3
Ground
Ground
R. x 10
169-5, Pin 4
1 3 1 (2nd contact
from inside)
T. B. 8, Term. 1 0
1 60, Term.
T. B . 8, Term. 10
1 2 3- 1 , Term. 1
12 1
R x lO
5
Resistance
(Ohms)
1 5 ,000
1 5,000
* 1 50 or
200
(Cont' d ) .
Probable Cause of Incorrect Reading
Defective resistor 145.
Same as above.
Open or shorted relay 1 3 1.
200
Open coil on relay 1 30 ; open or dirty contacts on
relay 1 3 1 .
50
Defective resistor 1 50.
2000
Defective resistor 1 5 3 - 1 or capacitor 102-6.
R x 10
2000
R x 10
2000
Open reactor 162 ; defective resistor
capacitor 1 10.
Defective resistor 1 5 3-4.
R x 10
180
o
1 5 3- 3
or
Short ground or open on secondary of transformer
160.
R x 10
Direct
2 10
Same as above.
No continuity.
1 2 3- 1 , Term.
1 58, Term.
1 2 3- 1 , Term. 2
Direct
1 2 3- 1 , Term.
Ground
Direct
5
2.5
Open or short in primary of transformer 1 58.
Same as above. No ground on center tap of transformer 1 58.
12 3-1, Term. 2
1 2 3- 1, Term. 2
1 2 3- 1 , Term. 3
Ground
1 58, Term. 3
Ground
Direct
1 2 3- 1, Term. 3
123-2, Term. 7
Direct
1 2 3- 1 , Term. 3
1 6 1 (outside
contact)
Direct
1 2 3- 1, Term. 4
1 30 (outside
contact)
Direct
1 2 3- 1, Term. 4
Ground
1 2 3- 1 , Term. 5
1 2 3- 1, Term. 5
Ground
Direct
1 30 (inside
contact)
Direct
1 2 3- 1 , Term. 6
1. 3 1 (outside
lug)
12 3-2, Term.
T. B. 5, Term. 2
Direct
Remove
modulator
tubes
Direct
1 2 3-2, Term.
T. B. 9, Term. 1
Direct
Direct
Direct
Relay 1 30
energized
Direct
1 2 3-2, Term. 2
1 70-2, Pin 7
Direct
1 2 3-2, Term. 2
l 7e - l , Pin 7
Direct
1 2 3-2, Term. 2
169-2, Pin 2
Direct
1 2 3-2, Term. 2
1 69- 1 , Pin 7
Direct
1 2 3-2, Term. 2
1 2 3-2, Term. 2
1 69-3, Pin 2
Direct
169-4, Pin 2
1 30 Coil (inside
lug)
Direct
1 2 3-2, Term. 2
Direc.t
Modulator
tubes
removed
1 2 3-2, Term. 2
13 1 Coil (inside
lug)
1 2 3-2, Term. 2
Ground
1 2 3-2, Term. 3
160, Term. 2
Direct
1 2 3-2, Term. 3
126, Term.
T. B. 7, Terms.
4, 5, 6
Direct
1 2 3-2, Term. 3
1 2 3-2, Term. 3
T. B. 8, Terms.
2, 4
Direct
Direct
Direct
Direct
o
2.5
o
o
o
o
o
o
o
o
o
Open or dirty cOiltacts on relay 1 3 1 or 1 6 1 .
Open o r dirty contacts o n relay 1 6 1 .
Same as above.
No continuity.
Defective relay 1 30.
No continuity.
Defective relay 1 30 .
N o continuity.
Defective relay 1 30.
No continuity.
No continuity.
No continuity.
No continuity.
o
No continuity.
o
o
o
o
o
o
200
o
o
o
o
* Equipment may be provided either with a 1 50-ohm or 200-ohm relay 1 3 1 .
5-1 2
Same as above.
No continuity.
o
o
Defective reactor 1 2 8-3.
No continuity.
No continuity.
No continuity.
No continuity.
No continuity.
No continuity.
No continuity.
Open or short in coil of relay 1 30 ; relay 1 3 1 contacts dirty or open.
No continuity.
No continuity.
No continuity.
No continuity.
AN 1 6-40S CR624-2
TABLE
5-5.
TRANSMITTE R CONTINU ITY A N D RESISTANCE MEASU REMENTS
To
From
Control '
Positions
If Not
Normal
Ohmeter
Scale
Used
1 2 3-2, Term. 4
T. B. 8, Term. 3
Direct
12 3-2, Term. 4
12 3-2; Term. 4
1 18
Direct
12 3-2, Term. 4
1 2 3-2, Term. 5
12 3-2, Term 6
1 2 3-2, Term. 7
1 14 (rotor)
T. B. 1, Term. 5
Direct
Direct
T. B. 4, Term. 5
T. B. 4, Term. 4
Direct
Direct
1 6 1 (inside
contact)
Direct
1 2 3-2, Terms. 7, 8
Ground
Direct
169- 1 , Pin 2
Ground
Direct
169- 1 , Pin 2
169-6, Pin 7
Direct
169- 1 , Pin 3 .
169- 1 , Pin 3
169- 1 , Pin 4
1 14 (stator)
1 18 (inside lug)
T. B. 1 ,
Term. 16
Direct
172, Term. 16
Ground
169- 1 , Pin 5
1 72, Term. 1 2
1 72, Term. 1 2
Ground
169- 1 , P i n 5
172, Term. 9
1 72, Term. 9
Ground
169- 1 , Pin 5
172, Term. 5
1 72, Term. 5
Ground
Operate "D" Direct
frequency
shifter
1 69- 1 , Pin 8
Ground
Direct
169- 1 , Pin 8
T. B. 1. Term. 7
Direct
1 70- 1, Pin 4
Ground
Direct
1 70- 1 , Pin 4
Ground
Direct
169-2, Pin 1
Ground
Direct
169-2, Pin 3
Direct
169-2, Pin 4
1 1 5 (stator)
T. B. 1, Term 2
169-2, Pin 7
Ground
Direct
1 7 � -2, Pin 4
1 70-2, Pin 1
1 70-2, Pin 2
1 70-2,
169-6,
169-6,
169-6,
1 69-6,
Pin
Pin
Pin
Pin
Pin
6
2
5
3
Section V
P a ra g r a p h 4c15 1-Ta b l e 5 - 5-(Cont'dl
Direct
Operate "A" Direct
frequency
shifter
Operate "A" Direct
frequency
shifter
Operate "B" Direct
frequency
shifter
Operate "B" Direct
frequency
shifter
Operate "C" Direct
frequency
shifter
Operate "C" Direct
frequency
shifter
Operate "D" Direct
frequency
shifter
Direct
Ground
Direct
Ground
Direct
T. B. 8, Term. 5
T. B. 8, Term. 5
Direct
Ground
Ground
Direct
Ground
169-6,
Pins, 4 ,6, 8
Direct
Direct
Direct
Direct
Resistance
(Ohms)
o
o
o
o
o
o
o
o
3
o
o
o
o
Open
o
Open
o
Open
o
(Cont' d ) .
Probable Cause of Incorrect Reading
No continuity.
No continuity.
No continuity.
No continuity.
No continuity.
No continuity.
No continuity.
No continuity. Open or dirty contacts on relay 1 3 1 .
Open o r short i n coil o f relay 1 30 ; relay 1 3 1 contacts dirty or open.
No continuity.
No continuity.
No continuity.
No continuity.
Shorted with 1 56.
No continuity.
Short in switch 1 56 .
N o continuity.
Short in switch 1 56.
No continuity.
Open
Short in switch 1 56.
40
Open or shorted reactor 128-2 ; shorted capacitor
103.
o
No continuity.
Open or short in coil of relay 130; 1 3 1 contacts
dirty or open.
o
No continuity.
o
o
o
o
o
o
No continuity.
No continuity.
No continuity.
No continuity.
o
No continuity.
o
Open reactor 1 2 7-4.
o
No continuity.
o
o
o
o
No continuity.
Open reactor 1 2 7-3.
No continuity.
No continuity.
No continuity.
5-1 3
Secti o n V
F i g ure S - 4A
AN 1 6-40SCR624-2
�
i��
o
TO
294,"'2- 2.35
:
MEGOHMS
TO GROUND- 270000 OHMS
TO
163-/
"
TO �.-----�
T8.
"'3 - Q25
1: 8 4 , #2 - 0.25
4,
B
T.B. S,
OHMS
OHMS
tI2. -34 0
./I'!7 - 3 4 0
T. B. 9. PlO-34 0
OHMS
TO GROUND-650QO OHMS
OHMS
296, #3 -0.25
2 9 6,
GROUND - 390 OHMS
GROUND-390
OHM S
212
-025
TO
TO
OHMS
OHMS
243-6, d3- 1 2 0 0 OHMS
OHMS
243-5, #6 - 2 . 2
';':""'_:::::"-�----;;�,j-I--fl,IIIIE'�'B;nI;;;-- TO
M EGOHM S
TO' -------....
T.8. 4, #1 - 0.25 O H M S
T.B & #8 -0. 2 5 OH M S
r.B. 5, tt:9 -Q · 25
r.e. 5, #15-025
T.6. 5, UI -D.25
OHMS
OHMS
OHMS
TB 5, 23 -0.2 5 OHMS
T.B 9, #- 1 1 - 02 5 OHMS
T.e. 8, /1:17- 02 � OHMS
T.a 7., .tr 2 - 0 2 5 OHMS
T.S. I , � I - 025 OHMS
T.6 I , � 5-025 OHMS
�
GROUND - 680000
OHMS
1: 6 . 5, ltI7- 0.2 5 OHMS
t--::t§���er-
TO GROUND-270 OHMS
-K.::.---:':\l...a-+-f -"��'-l-O-T
T.B. 2, 11:2-025 OHMS
288, #" 2 - 0 2 5 OHMS
T.8. 4, #4-0.25 OHMS
2 4 6 , It l - O 2 5 OHMS
243-4, .¢8-4700 OHMS
2 43-4 , #6- 82 0 00 OHMS
2 43-3. #8-4700 O H M S
T.8. 2, #3-02 5 OHMS
TO
GROUND -270 OHMS
GROUND - 65000
OHMS
2 4 3 - 2 , it s - 4 700 OHMS
T O ,·------/
29� 1t5-0 0 H M S
#"6 -3 5 0 000
GRQUND-350QOO
'." "-':=' �, R__ a
295, 117-0 OHMS
T.8. 8, # 9 - 0 O HMS
2 9 5,
TO' -------'
TO
GROUN D - I S OOO
TO
TO
GROUND-
MEGOHM
GRQUND-470 OHMS
TO GROUND """"'i 30000 OHMS
OHMS
T. B 5
0:
Figure S -4A .
5- 1 4
I
GROU N D - 4 70 OHMS
o
2IZ-C- ISOOOO OHMS
ToB. 8, l 3 - 160000 OHMS
2 1 1 - A - 150000
GROUND - 2 MEGOHMS
GROU N D - 20000
OHMS
T,e. B, # 1 1 & 1 2 - 1 800 OHMS
tt
OHMS
R adio R eceiver SC-624-A-Con tin uity Test Diagram
Section V
Para g ra p h 4cl5'-Ta b l e 5-5-lCont'dl
AN 1 6-40S C R 624-2
TABLE
i
From
5-5.
TRANSMITTE R CONTINU I TY A N D RESISTANCE MEASU REMENTS
To
Control
Positions
If Not
Normal
Ohmeter
SC"ale
Used
ResistanC"e
(Ohms)
(Cont' d ) .
Probable Cause of InC"orreC"t Reading
,
169-5, : Pin
169-5, Pin
169-5, Pin
169-5, Pin
169-5, Pin
1 69-5, Pin 7
Ground
Ground
1 10
169-5, Pin 5
T. B. 7,
Term. 14
1 2 3-2, Term. 2
1 69-5, Pin 7
Ground
169-5, Pin 8
169-3, Pin 1
169-3, Pin 3
169-3, Pin 4
126, Term. 2
Ground
160, Term. 3
169-4, Pin 4
169-3, Pin 4
169-3, Pin 5
169-3, Pin 7
169-3, Pin 8
169-4, Pin 1
169-4, Pin 3
111
1 59, Term. 3
2
3
3
6
169-4, Pin 3
169-4, Pin 5
169-4, Pin 7
169-4, Pin 8
T. B. 8, Term. 10
T. B. 8, Term. 1 0
T. B. 8, Term. 7, 8
T. B. 8, Term. 8
T. B. 8, Term. 2
Ground
Ground
Ground
160, Term.
T. B. 7, Term. 3
1 59, Term. 5
Ground
Ground
160, Term. 4
120
1 19
1 7 1 (outside
contact)
1 7 1 (inside
contact)
T. B. 8, Term. 9
1 7 1 (outside
contact)
T. B. 8, Term. 3
1 7 1 inside
contact)
T. B. 8, Term. 10
171 (outside
contact)
T. B. 8, Term. 4
1 7 1 (inside
contact)
T. B. 8, Term. 1 2
1 7 1 (outside
contact)
T. B. 8, Term 6
1 7 1 (inside
contact)
T. B. 8, Term. 5
1 7 1 (outside
contact)
Direct
Direct
Direct
Direct
Direct
Tube VTDirect
199, speech
amplifier
removed
Direct
Tube VT199, speech
amplifier
in socket
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Meter
switch
position
Direct
Meter
switch
position
Direct
Meter
switch
position 2
Direct
Meter
switch
position 2
Meter
Direct
switch
position 3
Meter
Direct
switch
position 3
Meter
Direct
switch
position 4
Meter
Direct
switch
position 4
Meter
Direct
switch
position 5
0
0
0
No continuity.
No continuity.
Open reactor 162.
No continuity.
No continuity.
41
Defective resistor 1 2 3 - 1 or 143-2.
7
Defective Tube VT- I99; wrong socket connections.
0
0
0
0
No
No
No
No
No
No
No
No
No
0
No continuity.
0
No
No
No
No
No
0
0
0
0
0
0
0
0
0
0
0
0
continuity.
socket connection.
continuity.
continuity.
continuity.
continuity.
continuity.
continuity.
continuity.
continuity.
continuity.
continuity.
continuity.
continuity.
0
0
No continuity.
No continuity.
No connection.
0
No connection.
0
No connection.
0
No connection.
0
No connection.
0
No connection.
0
No connection.
0
No connection.
0
No connection.
5-1 5
AN 1 6-40S C R624-2
Secti o n V
Para g ra p h 4d-4d(4)
TABLE
5-5.
TRANSMITTER CONTINU ITY A N D RESISTA N C E MEASUREMENTS
To
From
T. B. 8, Term. 1 1
1 5 7, Outside contact
126, Term. 1
Control
Positions
If Not
Normal
1 7 1 (inside
contact)
1 7 1 (inside
contact)
Ohmeter
Scale
Used
Resistance
(Ohms)
Direct
0
No connection.
Direct
1.5
Resistor 1 34 defective or disconnected.
Position
Position
Position
Position
Direct
Direct
R x 10
Direct
R x 1000
0.75
0.75
2000
75
5000
Resistor
Resistor
Resistor
Resistor
Reactor
2
3
4
5
d. RECEIVER CONTINUITY AND RESISTANCE
MEASUREMENTS.
N ote
The following measurements apply to both
Radio Receiver BC-624-A or BC-624-AM un­
less otherwise specified.
RADIO REC EIVER B C - 6 2 4 - A
1 3 5 - 1 defective or disconnected.
1 3 5-2 defective or disconnected.
1 5 3-2 defective or disconnected.
148 defective or disconnected.
126 open or shorted.
( 2 ) Leave all the vacuum tubes in their sockets un­
less otherwise specified.
( 3 ) Rotate the "AUDIO" and "RELAY" controls
fully clockwise unless oth�rwise specified.
(4) Using Test Set 1-56- ( * ) or equivalent, make
the resistance measurements listed in the following table:
N ote
( 1 ) Lift the receiver side of the rack while pressing
the top of the receiver down with the thumbs. Lift the
rack away from the receiver.
5 -6A.
Probable Cause of Incorrect Reading
Meter
switch
position 5
Position 1
126, Term. 2
TABLE
( Cont ' d ) .
Variatiohs greater than plus or minus 10 per­
cent from the values listed in the chart indicate
defective circuits.
OR
BC-624 -AM-CONTINU ITY A N D
RESISTA N C E MEASU REMENTS.
From
To
Ohmmeter
Scale Used
Resistance
* 2 3 1 , Pin 3
2 3 1, Pin 3
T. B. 4, Term. 1
T. B. 5, Term 8
Direct
Direct
0.25
0.25
2 3 1, Pin
2 3 1 , Pin
2 3 1 , Pin
2 3 1 , Pin
2 3 1, Pin
2 3 1 , Pin
2 3 1 , Pin
2 3 1, Pin
2 3 1 , Pin
2 3 1 , Pin
2 3 1, Pin
2 3 1 , Pin
2 3 1, Pin
2 3 1, Pin
2 3 1 , Pin
2 3 1 , Pin
2 3 1 , Pin
2 3 1, Pin
23 1, Pin
2 3 1 , Pin
t2 3 1 , Pin
t2 3 1 , Pin
t2 3 1, Pin
t2 3 1, Pin
2 3 1 , Pin
2 3 1 , Pin
t2 3 1, Pin
T. B. 5, Term. 1
T. B. 5, Term. 9
T. B. 5, Term. 1 5
T. B. 5, Term. 1 7
T. B. 5, Term. 2 3
T. B. 9, Term. 1 1
T. B. 8, Term. 1 7
T. B. 7, Term. 2
T. B. 1, Term. 1
T. B. 1, Term. 5
T. B. 2, Term. 3
T. B. 2, Term. 2
288, Term. 2
T. B. 4, 1;erm. 4
246, Term. 1
296, Term. 7
T. B. 4, Term. 2
T. B. 4, Term 3
2296, Term. 3
2 12B (red)
2 1 1C
2 1 1- 1 C
T. B. 9, Term. 7
T. B. 10, Term. 1
T. B. 5, Term. 1 1
T. B. 5, Term. 3
T. B. 1, Term. 5
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
0.25
0.25
0.25
0.25
0.2 5
0.25
0.25
0.25
0.25
0.25
0.25
0.2 5
0.25
0.25
0.25
0
0.25
0.25
0.25
0.25
0
0
0
0
0
0
0 -
5-1 6
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
4
5
5
5
5
6
6
6
6
6
6
6
Probable Cause of Trouble
Defective B+ r-f reactor 24 1-2.
Defective B + reactor 24 1-2, or open on B+
bus.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Open audio-output wiring.
Defective B+ reactor 24 1-3.
Same as above. Or broken jumper on T. B. 4.
Defective reactor 24 1-3 or open B+ wiring.
Same as above.
Broken connection.
Same as above.
Broken connection or open A VC bus.
Same as above.
Same as above.
Same as above.
Same as above.
AN
TABLE 5 - 6A.
Secti o n V
P a ra g ra p h 4dl41-T a b l e 5 - 6A ICont'dl
1 6 -40S C R 624-2
RADIO RECE IVER BC-624-A OR BC-624 -AM-CONTINU ITY AND
RESISTANCE MEASU REMENTS (Con't) .
To
From
Ohmmeter
Scale Used
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
R x 1000
Resistance
o
o
o
o
o
o
o
o
o
o
o
:j:2 3 1 , Pin 6
2 3 1, Pin 7
2 3 1 , Pin 8
2 3 1 , Pin 8
2 3 1 , Pin 8
2 3 1, Pin 8
2 3 1 , Pin 8
2 3 1, Pin 8
2 3 1 , Pin 8
2 3 1, Pin 8
2 3 1 , Pin 8
2 3 1 , Pin 8
2 3 1, Pin 9
2 3 1, Pin 9
2 3 1 , Pin 10
231, Pin 10
231, Pin 1 1
2 3 1 , Pin 1 2
2 3 1 , Pin 1 2
243-2, Pin 1
243-2 Pin 2
243-3, Pin 1
243-3, Pin 2
243-4, Pin 1
243-4, Pin 2
243-5, Pin 1
243-5, Pin 2
243-5, Pin 6
243-5, Pin 6
243-5, Pin 8
243-6, Pin 1
T. B. 1, Term. 7
Ground
2 13
T. B. 1, Term. 2
T. B. 2, Term. 1
243-2, Pin 7
243-3, Pin 7
243-4, Pin 7
243-5, Pin 7
243- 1, Pin 8
243-6, Pin 2
Ground
295, Term. 7
T. B. 8, Term. 9
295, Term. 3
Ground
295, Term. 5
295, Term. 4
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
2 1 1B
2 1 1- 1B
T. B. 8, Term. 4
Ground
243-6, Pin 7
243- 1, Pin 7
§243- 1, Pin 5
Ground
Ground
Crystal-holders
A, B, C, D
Plate inductors
227- 1, -2, -3, -4
296, Term. 6
296, Term. 7
296, Term. 5
296, Term. 5
Ground
Ground
2 12 A (Blue)
296, Term. 2
T. B. 6, Term. 7
243-6, Pin 3
T. B. 9, Term. 10
Ground
Direct
Direct
Direct
243-2, Pin 3
243-3, Pin 3
Ground
Ground
R x 10
R x 10
390
2 70
243-3, Pin 5
243-4, Pin 3
Ground
G round
R x 10
R x 10
2 70
470
243-4, Pin 5
243-5, Pin 8
243- 1, Pin 4
Ground
T. B. 8, Terms. 1 1, 12
Ground
R x 10
R x 100
R x 100
470
1,800
2,700
243-4, Pin 8
R x 100
4,700
243-4, Pin 6
R x 1000
§243- 1, Pin 6
t2 3 1 , Pin 4
:j: 2 3 1 , Pin 4
t2 3 1 , Pin 4
:j: 2 3 1 , Pin 4
:j:2 3 1, Pin 4
:j: 2 3 1 , Pin 4
2 3 1 , Pin 5
2 3 1, Pin 5
2 3 1, Pin 5
2 3 1, Pin 5
2 3 1 , Pin 5
243-2, Pin 5
2 3 1 , Term. 3
t2 3 1 , Term. 3
Direct
R x 10
R x 10
R x 10
Direct
R x 10
Direct
Rx
Rx
Rx
Rx
Rx
Rx
lO
10
10
100
10
10
o
o
o
1.5
o
o
3.5
o
o
o
o
o
o
o
o
o
3.5
o
Open
o
o
o
o
350
350
375
10
400
45
340
340
340
1200
340
390
82,000
Probable Cause of Trouble
Sa in e as above.
Broken connection.
Broken connection or open heater.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Broken connection or open heater.
Same as above.
Same as above. Defective tube.
Broken connection.
Same as above.
Same as above.
Broken connection or defective transformer 295.
Brok en connection.
Broken connection.
Broken connection or defective transformer 295.
Broken lug or open ground bus.
Same as above.
Same as above.
Same as " above.
Same as above.
Same as above.
Same as above.
Same as above.
Broken connection.
" Same as above.
Defective 2nd audio tube JAN- 12)5GT
(VT- 1 3 5 ) .
Broken lug o r open ground bus.
Same as above.
Broken connection or defective crystal switch
286.
Same as above.
Defective transformer 296.
Same as above.
Same as above.
Open reactor 241-3; defective transformer 296
Same as above.
Same as above.
Same as above.
Same as above.
Shorted capacitor 202-24, 206- 5 ; open resistor
268.
Same as above.
Shorted capacitor 202-25, 206-9 ; open resistor
269.
Same as above.
Shorted capacitor 202-26, 206- 12 ; open resistor
270.
Same as above.
Defective resistor 2 77.
Defective Tube VT-207, capacitor 206-2
resistor 265.
Defective transformer 294, capacitor 2 06- 14,
resistor 263-4" reactor 24 1-2.
Defective resistor 2 7 1 , reactor 24 1-2, capa«;itor
206- 13.
5-1 7
Secti o n V
Paragra p h 4d(41-Ta b l e 5 -6A-(Cont'dl
TABLE 5 - 6A.
AN 1 6-40S C R624-2
RADIO RECE I VE R BC-624-A OR BC-624 -AM-CONTINU ITY A N D
RESISTANCE MEASUREMENTS ( C o n ' t) .
To
From
Ohmmeter
Scale Used
*2 3 1 , Term. 3
243-4, Pin 6
R x 1000
2 3 1, Term. 3
243-3, Pin 8
R x 100
2 3 1, Term. 3
243-3, Pin 6
R x 1000
2 3 1 , Term. 3
243-3, Pin 8
R x 100
2 3 1 , Term. 3
243-2, Pin 6
R x 1000
2 3 1 , Term. 3
§ 2 3 1 , Term. 3
243- 1, Pin 3
2 4 1 - 1 , Pin 6
R x 1000
R x 1000
2 3 1, Term. 3
243- 1, Pin 2
R x 1000
2 3 1, Term. 3
Ground
R x 1000
243-5, Pin 8
Ground
R x 1000
Ground
Ground
Ground
243-5, Pin 3
R
R
R
R
2 3 1 , Term. 5
'
243-5, Pin 6
2 3 1, Term. 5
Ground (30 seconds)
R x 100
2 3 1 , Term. 6
Ground
R x 1000
2 3 1 , Term. 6
2 3 1 , Term. 6
2 3 1 , Term. 9
243-3, Pin 4
243-2, Pin 4
Ground
R x 1000
R x 1000
R x 1000
2 3 1 , Term. 9
2 3 1, Term. 1 1
295, Term. 6
Ground
R x 1000
R x 1000
243-2, Pin 6
Ground
R x 1000
243-3, Pin 6
Ground
R x 1000
t243-4, Pin 4
Ground
R x 1000
*243-4,
t243-4,
*243-4,
t243-5,
Pin
Pin
Pin
Pin
4
6
6
4
Ground
Ground
Ground
Ground
Rx
Rx
Rx
Rx
*243-5,
243-5,
t243-5,
*243-5,
243-6,
t243- 1,
Pin
Pin
Pin
Pin
Pin
Pin
4
5
6
6
5
1
Ground
Ground
Ground
Ground
Ground
294, Term. 2
R x 1000
R x 1000
294, Term. 2
R x 1000
T. B. 8, Terms. 1 1, 12
11 243- 1, Pin 2
11243- 1, Pin 2
2 3 1 , Term. 5
*243- 1, Pin
243- 1, Pin 5
295, Term. 1
5-1 8
Ground
246, Term. 4
x
x
x
x
1000
1000
1000
1000
1000
1000
1000
1000
R x 100
R x 1000
R x 1000
R x 1000
Resistance
Probable Cause of Trouble
Defective resistor 2 79-4, reactor 24 1-2, capacitor
206- 1 l .
4,700
Defective transformer 293, resistor 263-3,
reactor 24 1-2, capacitor 206- 1 l.
Defective resistor 267-5, reactor 24 1-2, capacitor
62,000
206- 10.
Defective transformer 292, resistor 263-2, re­
4,700
actor 24 1-2, capacitor 206-7.
Defective resistor 267-2, reactor 24 1-2, capaci­
62,000
tor 206-6.
Open coil of relay 246; defective reactor 24 1-2.
5,000
Open inductors 227- 1, -2, -3, -4 ; defective
10,000
switch 286; open resistor 264 or reactor
24 1-2; defective capacitors 206- 1, 202-2 7 and
205.
Defective potentiometer 2 37, resistors 279- 1,
50,000
279-2 ; open reactor 24 1-2, resistor 282.
Short on B+ bus to ground; defective resistor
50,000
279- 1 , 297-2, potentiometer 2 37, resistor 282,
267-5, 267-6, 267-2, 267-3.
Shorted capacitor 2 1 1A, 2 12C; defective resistor
20,000
276, 277.
Same as above.
18,000
5,000
Defective potentiometer 2 37, resistor 282.
Defective potentiometer 2 37, resistor 265-2.
4,700
Defective transformer 296; open reactor 24 1-3
220,000
or defective resistor 266-3.
Defective transformer 296, reactor 24 1-3, resis­
tor 2 74-2.
Shorted capacitor 202- 17, 2 1 1B, 203-4, 206- 18,
80,000
2 12A, 2 12B; defective tube JAN- 12C8 (VT169) or tube JAN- 12J5GT (VT- 1 3 5 ) .
Shorted capacitor 2 1 1C, 206-8, 206-4, 202-2,
740,000
short on AVC bus.
Defective transformer 292 or resistor 267-4.
100,000
Defective transformer 291 or resistor 267- l .
100,000
Defective tube JAN- 12C8 (VT- 169) o r open re350,000
sistor 275-2, 2 7 5-3, 262-2, 276; open secondary
of transformer 295; shorted capacitor 2 14.
2 50,000
Open resistor 262-2 ; same as above.
Defective transformer 295; shorted capacitor
650,000
2 14.
Defective resistor 267-3; shorted capacitor
65,000
206-6.
Defective resistor 267-6 ; shorted capacitor
65,000
206- 10.
1 megohm Defective transformer 293 or resistor 280;
shorted capacitor 2 06-2 3.
Defective transformer 293.
o
Shorted capacitor 206- 13.
1 30,000
100,000
300,000
Defective transformer' 294; ground in detector
circuit wiring.
45,000
470,000
Ground in AVC wiring.
Shorted capacitor 2 1 1B, 2 12A or 2 12B.
2 megohms Shorted capacitor 2 1 1- 1B, 2 1 2A, 2 12B.
680,000
Defective resistor 2 58.
2.35
Defective Tube VT-207 ; open resistor 2 74- 1,
28 1 ; shorted capacitors 206- 16, 209, 2 10.
82,000
Defective tube JAN- 12AH7GT, open resistor
2 7 1-2, shorted capacitor 2 10.
Defective switch 286 or open resistor 266- l .
270,000
1 30,000
Read justments required o n relay 246 contacts;
defective resistor 272 or 273.
47,000
AN 1 6- 40S CR624-2
TABLE 5 -6A.
Section V
Para g ra p h 4d(4)-Ta b l e 5 -6A-Ta b l e 5-6B
RADIO RECEIVER BC-624 -A OR BC-624 -AM--CONT I N U ITY AND
RESISTA NCE MEASU REMENTS (Con ' t) .
Obmmeter
Scale Used
To
From
2 1 1A
2 1 1- 1A
2 12C
2 1 2C
T. B. 8, Term. 1 3
T. B. 8, Term. 1 3
294, Term. 2
Rx
Rx
Rx
Rx
Rx
Rx
Rx
1000
1000
1000
1000
1000
1 000
1000
1 50,000
1 50,000
1 50,000
1 5 0,000
150,000
1 50,000
82,000
:j:2 1 1-2A, 2 1 1-2B
243-7, Pin 8
R x 1000
120,000
:j:243-7, Pin 8
Ground
R x 1 000
2 50,000
:j:243-7, 4
:j:243-4, Pin 8
Ground
243-5, Pin 5
R x 1000
Direct
330
5 5 0,000
tT. B. 9, Terms. 4, 1 5
:j:T. B . 10, Term. 2
T. B. 9, Terms. 4, 1 5
:j:T. B . 10, Term. 2
* *T. B. 9, Terms. 4, 1 5
ttT. B . 10, Term. 2
:j:2 1 1-2A, 2 1 1-2B
Probable Cause of Trouble
Resistance
Defective "AUDIO" control potentiometer 2 36.
Same as above.
Same as above.
Open bus, broken connection, defective resistor
2 7 1-2.
Open bus, broken connection, defective resistor
2 72-2.
Shorted capacitor 2 19, broken connection, de­
fective resistor 2 72-2, 2 76-2, 264-2, 277, 2 76- 1 .
Defective tube 243-7, defective resistor 2 5 3-3.
Shorted capacitor 203.
�3000
*A defective capacitor 206 - 1 5 m a y be responsible f o r m a n y incorrect
readings involving plug 2 3 1 , pin 3 .
t Radio Receiver BC-624-A only.
�Radio Receiver BC-624-AM only_
* Operate corresponding channel slides.
( Radio Receiver
1 1 3000 with "RELAY " control fully clockwise.
,
BC-624·A only . )
with
" RELAY "
BC-624-AM onl)·. )
control
fully
clockwise.
( Radio
Receiver
" Resistance varies with setting of " AUDIO" control.
BC-624-A only . )
( Radio Receiver
t t Resistance varies with setting of " AUDIO" control.
BC-624-AM only . )
(Radio Receiver
N ote
The following resistance measurements were
made with Voltmeter 1-1 76, part of Test
Equipment I-56-K, ( 1000 ohms-per-volt) .
Depress the "OFF" button to be sure the
equipment is not operating. Disconnect the
equipment from the power source. Remove the
4 red receiver mounting screws. Lift the re­
ceiver side of the rack away from the receiver.
Make all resistance measurements from the
tube socket pins to the chassis. Place the
"AUDIO" and "SQUELCH" or "RELAY"
controls in the fully clockwise position.
TABLE
Tube
JAN-9003
VT·203
JAN-9003
VT-203
5 -6B.
RADIO
RECEIVER BC-624 -C-CONTI N U ITY A N D
RESISTANCE
Function
Pin
Number
Element
Scale Used
Ohms
R-f amplifier
1
G,
R x 1000
2,000,000
2
K
Rx 1
330
3
H
H
Low
Low
0
4
5
P
R x 1000
100,000
6
G2
R x 1000
200,000
7
K-G3
3.2
Rx l
3 30
G,
R x 1000
2,000,000
2
K
Rx l
1 ,000
3
H
Low
3.2
Mixer
MEASU REMENTS.
Probable Cause of '
Incorrect Reading
Shorted capacitors 2 0 1 , 202-2, 2 1 l-4B,
defective resistors 2 5 1, 2 5 2- 1.
Shorted capacitors 20'2- 1 , 202-4, defective resistors 2 5 3- 1 .
Broken connection.
Shorted capacitors 202- 18, 202- 19,
broken connections.
Defectiv� inductor 223, defective resistors 2 30- 1 , 2 30-2, shorted capacitors
202-4, 202-5.
Shorted capacitor 202-3, 'defective reo
sistor 267-8.
Same as for pin 2 .
Shorted capacitor 2 0 3- 1, defective resistor 2 5 5 - 1 .
Shorted capacitors 202-6, 206- 3, defective resistor 2 56.
Shorted capacitors 202- 18, 202- 1 9,
broken connection.
5 19
-
." VI
_. 11/
VI
W
C
..
11/
I
�
o
VI
_
0
:::I
1, <
TB. 9
T8 5
n
-.
g:/
��
:::;:
.� E
�
�
")
'" '
�
'
lJ)
�
���
TB. 6
�
Z
0-
I
�
o
VI
n
:lI:I
0�
�
I
�
el l ® � @
�I I
W '<D
'"
Figure 5 - 4 8 .
�
II
I'l
""ry
ry""
9
7
5
R a dio R e ceiver B C - 624-C-Lo cation
ClJ
®--@--@
o f Compon e nts Termin als
TB. 8
®
@ CD
®
TB. IOL
a n d Term in a l B oards
I I
�
..�
r--; �
�VTB IOR
S e cti o n V
P a ra g ra p h 4d(4}-Ta b l e 5 - 6 B-( C o n t ' d }
AN 1 6-40S C R 6 2 4 - 2
TABLE 5 - 6B.
Tube
RADIO
Function
RECEIVER
BC-624 -C-CO NTINU ITY A N D
Pin
Number
Element
4
H
5
p
6
7
JAN-9003
VT-203
K-G,
Harmonic
amplifier
Probable Cause of
Incorrect Reading
Low
1.5
Shorted capacitors on filament bus,
broken connection.
R x 1000
100,000
Defective transformer 2 9 1 , defective
resistor 263- 1, shorted capacitor
206-3.
R x 1000
360,000
Shorted capacitor 202-7, defective re­
sistor 2 5 7- 1 .
Rx l
1 ,000
Same a s for pin 2 .
R x 1000
2,000,00
Shorted capacitor 203-2, defective re­
sistor 2 5 5-2.
Rx l
330
Shorted capacitors 2 02-9, 202- 1 1 , de­
fective resistor 2 5 3-2 .
3
H
Low
3.2
Shorted capacitors 202-22, 202-23,
broken connectioR.
4
H
Low
1.5
Shorted capacitors on filament bus,
broken connection.
R x 100
100,000
Defective inductor 2 2 5 , shorted ca­
pacitors 202-8, 202- 10, defective re­
sistors 2 30-3, 2 30-4.
R x 100
200,000
Shorted capacitor 202- 12, defective re­
sistor 267-7.
p
Rx l
330
Same as for pin 2.
R x 1000
1 2 5 ,000
Defective inductor 226, shorted capaci­
tors 202- 13, 202- 14, defective re­
sistor 260.
K
Rx l
1 ,000
Defective resistor 2 6 1 , shorted capaci­
tor 202- 1 5 .
7
Harmonic
generator
2
p
K-G,
3
H
Low
4
H
Low
5
P
o
Broken connection.
3.2
Shorted capacitors 202-22, 202-23,
broken connection.
R x 1000
12 5,000
Same as for pin 1 .
6
G
R x 1000
500,000
7
K
Rx l
1 ,200
Shorted capacitors 204, 2 0 5 , defective
resistor 262- 1 .
Same a s for pin 2 .
S
Low
2
H
Low
3
K-G,
Rx l
300
Shorted capacitor 206-5, defective re­
sistors 269-2, 287, broken connection.
4
G,
R x 1000
2 ,000,000
Defective transformer 2 9 1 , shorted capacitors 206-4, 2 1 1-4B, defective re­
sistor 267- 1 .
5
K-G,
Rx l
300
Same as ' for pin 3.
6
Go
R x 1000
75,000
Shorted capacitor 206-6, defective ' resistors 2 33- 1 , 2 33-2, 267-2, 267-5,
2 33-3, 2 3 3-4.
7
H
P
Low
1.5
Shorted capacitor o n filament bus.
R x 1000
100,000
Defective transformer 292, shorted
capacitor 206-7, defective resistor
263-2.
S
Low
First i-f
amplifier
8
JAN- 1 2 SG7
VT-209
Ohms
(Cont' d ) .
K
6
JAN- 12SG7
VT-209
Scale Used
MEASU REMENTS.
2
5
JAN-9002
VT-202
RESISTA N C E
Second i-f
amplifier
2
H
Low
3
K-G,
Rx l
o
o
o
o
180
Broken connection o r lug.
Same as for pin 1 .
Broken connection or lug.
Same as for pin 1 .
Shorted capacitors 206-8, 206-9, 20225, defective resistor 283.
5-21
Section V
Paragra p h 4dl41-Ta b l e 5-6B-lCont'dl
AN 1 6-40SCR624-2
TABLE 5 -6B. RADIO RECEIVER BC-624-C-CONTINUITY AND RESISTANCE MEASUREMENTS. (Cont'd) .
Tube
JAN- 12SG7
VT-209
Function
Pin
Number
Element
Scale Used
Ohms
4
G,
R x 1000
2,000,000
180
Same as for pin 3.
R x 1000
75,000
Shorted capacitor 206- 10, defective resistors 2 3 1-3, 2 3 1-4, 267-5, 233- 1,
233-2, 267-2.
Low
1.5
Shorted capacitor o n filament bus.
R x 1000
100,000
Defective transformers 293, shorted
capacitors 206- 1 1 , defective resistor
263-3.
K-G3
G,
7
H
8
P
S
Low
2
H
Low
3
K-G3
Rx 1
4
G,
Low
K-G3
Rx l
270
Same as for pin 3.
R x 1000
1 50,000
Shorted capacitors 206- 1 3, 206- 15, de­
fective resistors 267-9, 267- 10, de­
fective reactor 241-5.
Third i-f
amplifier
o
o
270
o
Broken connection or lug.
Same as for pin 1 .
Shorted capacitors 206- 12, 202-26, de­
fective resistor 269-3.
Defective transformer 293, broken
ground lug.
6
G,
7
H
Low
1.5
Shorted capacitor on filament bus.
8
P
R x 1000
100,000
Defective transformer 294, shorted ca­
pacitors 206- 14, 206- 15, defective re­
sistor 263-4, defective reactor 241-5.
G,
R x 1000
1,800,000
Shorted capacitors 2 1 1-4B, 2 1 1-3B,
202-28, 206-27, 202-30, 2 1 1-3A, 2 10,
defective resistors 2 58-2, 276-2, 290,
280-2, 27 1-3, 2 77-2, 276- 1 .
K,
Rx 1
600
Defective resistors 2 39, 273-2.
R x 1000
1,800,000
Same as for pin 1 .
K,
R x 100
30,000
Shorted capacitors 206-25, 2 1 1-4A, defective resistors 285, 284, 278- 1, de­
fective potentiometer 2 38-A.
G,
R x 1000
2,300,000
Shorted capacitors 202-29, 206-24, defective resistors 274-3, 275-4, 284,
278- 1, defective potentiometer
2 38-A.
R x 100
20,000
Shorted capacitor 2 1 1-4A, defective
resistors 273-3, 284, 278- 1, defective
potentiometer 2 38-A.
AVC delay
and first
audio
3
4
5
p,
6
o
7
H
Low
8
H
Low
S
Low
2
H
Low
3
P
R x 1000
325,000
Shorted capacitors 203-4, 2 12-A,
2 1 2-B, defective resistors 266-4,
2 34- 1, 2 34-2 273-3, 284, 2 78- 1, de­
fective potentiometer 2 38-A.
R x 1000
1 10,000
Shorted capacitor 2 12-C, defective re­
sistors 27 1-3, 277-2, 276- 1.
1 10,000
Same as for pin 4.
AVC and sec­
ond audio
4
5
5-22
Rx 1
5
2
JAN- 12C8
VT- 169
Defective transformer 292, shorted capacitors 2 1 1-4C, 206-8, 2 1 1-4B, de­
fective resistors 267-4.
6
5
JAN- 1 2AH7GT VT-207
Probable CalISe of
Incorrect Reading
1.5
o
o
Broken connection or lug.
Shorted cap.acitor o n filament bus.
Broken connection or lug.
Same as for pin 1 .
AN
TABLE 5 -6B.
Tube
Fun�tion
Pin
Number
Element
R x 1000
1,000,000
Low
R x 100
1.5
20,000
Cap
G,
R x 1000
600,000
o
S
Low
H
P
Low
R x 1000
1.5
1 10,000
R x 1000
1.10,000
G,
R x 1000
700,000
7
8
H
K
No con­
nection
Low
Rx 1
o
1
G,
R x 1000
3,000,000
R x 100
6,500
R x 1 000
475,000
R x 100
2,500
4
5
6
2
3
p,
4
5
6
7
8
jAN- 12H6
VT-2 14
Ohms
H
K
Third audio
Oscillator
and audio
squelch
S�ale Used
7
8
2
3
jAN- 12AH7GT VT-207
Para g ra p h
V
4d(4)-Table 5-6B-(Cont'd)
RADIO RECEIVER BC-624-C-CONTINUITY AN D RESISTANCE MEASUREMENTS. ( Cont'd ) .
6
jAN- 12A6
VT- 1 34
Secti o n
1 6-40SCR624-2
Detector and
Noise
Limiter
2
3
H
H
6
7
8
275,000
o
1.5
o
S
Low
H
P2
Low
R x 1000
1.5
1 ,000,000
R x 1000
1,000,000
R x 1000
1,000,000
4
5
R x 1000
This in an
open circuit
with chan­
nels disengaged
Low
Low
500
p,
No con­
nection
H
K,
Low
R x 1000
o
1 ,400,000
Probable Cause of
Inforre�t Reading
Shorted capacitor 2 1 1-3C, defective
resistor 280-3.
Shorted capacitor o n filament bus.
Shorted capacitor 2 12-C, defective resistors 277-2, 276- 1 .
Defective resistors 280-4, 280-5, 2 76- 1,
257-2, transformers 295, reactor
241-4, shorted capacitor 2 14.
Broken connection or lug.
Shorted capacitor on filament bus.
Defective transformers 200, shorted
capacitors 2 12-A, 2 12-B, defective
resistor 264-3.
Shorted capacitors 2 12-A, 2 12-B or
defective resistor 264-3.
Shorted capacitor 206-26, defective
resistor 2 58-3.
Same as for pin 1 .
Shorted capacitor 2 12-D o r defective
resistors 2 35- 1 , 2 35-2.
Shorted capacitor 206- 16, defective re­
sistors 274- 1, 276-2, 290, 280-2,
27 1-3, 277-2, 2 76- 1 .
Defective potentiometer 238-A, defec­
tive resistor 2 78- 1 .
Defective resistors 2 75-4, 284, 2 78- 1 ,
defective potentiometer 2 38-A.
Shorted capacitor 206-2, defective re­
sistor 265- 1 .
Defective resistor 28 1-4.
Shorted capacitor 205.
Broken connection or lug.
Shorted capacitor on filament bus.
Broken connection or lug.
Shorted capacitor on filament bus.
Shorted capacitors 2 10, 206-27, 202,
30, 2 1 1-3A, defective resistors 2 76-2,
290, 280-2, 2 7 1-3, 277-2, 2 76- 1 , de­
fective transformer 294.
Shorted capacitors 2 UI, 206-27, 20230, 2 1 1-3A, defective resistor 280-2,
2 7 1 -3, 277-2, 276- 1 .
Shorted capacitors 2 10, 206-27, 20230, 2 1 1-3A, defective resistors 290,
280-2, 27 1-3, 277-2, 2 76- 1 .
Same as for pin 1 .
Shorted capacitors 206- 17, 202-28, 2 1 13B, 206-27, 202-30, 2 1 1-3A, defec­
tive resistors 28 1-3, 28 1-2, 2 76-2,
290, 280-2, 27 1-3, 277-2, 2 76- 1 .
5-23
S e cti o n V
P a ra g ra p h 4e-4e(3)
e.
AN
1 6 -40S C R 6 2 4 - 2
RACK CONTINUITY AND RESISTANCE
MEASUREMENTS.
( 1 ) In addition to the tests shown below, all con­
nections, other than ground wires shown, should indi­
cate infinite resistance to ground (the rack frame) . All
Jones plug connections should indicate infinite resist­
ance to adj acent connections on the same plug.
TABLE
From
4 1 7,
4 1 7,
4 1 7,
4 1 7,
4 1 7,
Term.
Term.
Term.
Term.
Term.
1
2
2
2
2
5 - 7.
RAC K CONTI N U ITY A N D RESISTA N C E MEASU REMENTS.
To
420, Term. 2
420, Term. 2
420, Term. 2
420, Term. 1
420, Term. 3
420, Term. 7
420, Term. 12
420, Term. 8
4 18-2, Term. 4
4 18-2, Term. 4
Ground
420, Term. 4
4 18-2, Term. 2
4 19, Term. 8
4 19, Inside coil con­
nection
4 1 1 - 1 , Outside coil
connection
406, Breaker point
426. Outside connec­
tion next to 4 1 1- 1
4 19, Term. 4
427, Moving arm,
section A
427, Moving arm,
section B
4 18- 1 , Term. 1
4 18- 1 , Term. 2
427, Moving arm,
'
section C
4 18- 1 , Term. 5
427, Moving arm,
section D
4 19, Term. 12
4 19, Term. 10
4 18- 1 , Term. 6
420, Term. 5
420, Term. 6
4 18-2, Term. 7
4 18- 1, Term. 4
4 1 2, Outside coil
connection
4 1 1- 1 , Outside contact
4 18- 1, Term. 3
420, Term. 10
402, Inside connection
4 1 8-2, Term. 3
4 12, Armature 7
4 19, Term. 5
4 1 8-2, Term. 1
Ground
Ground
Ground
4 19, Term. 6
4 12, Contact No. 8
4 12, Contact No. 7
4 18-2, Term. 5
4 1 8-2, Term. 6
4 18-2, Term. 8
4 19, Term. 9
4 19, Term. 1 1
Ground
4 1 7, Term. 2
4 1 7, Term. 2
4 1 7, Term. 2
4 1 7, Term. 3
4 1 7, Term. 4
4 1 7, Term. 5
4 1 7, Term. 6
4 1 7, Term. 7
4 1 7, Term. 8
4 1 7, Term. 9
4 1 7, Term. 9
4 1 7, Term.
4 1 7, Term.
4 1 7, Term.
4 17, Term.
4 1 7, Term.
4 1 7, Term.
4 1 7, Term.
4 1 7, Term.
10
11
12
13
14
15
16
17
4 1 7, Term. 1 7
4 1 7, Term. 18
420, Term. 2
420, Term. 2
5-24
( 2 ) In all cases, the terminology inside and outside
refers to the center of the rack or the outer edges of the
rack, relative to the connections made to any part of the
particular component under test.
( 3 ) In the following test data, the contact springs
of relay 4 1 2 have been numbered from the outside con­
tact toward the relay coil. Since eight springs are used,
number 8 is therefore the spring adj acent to the coil.
Control
Positions
If Not
Normal
Ohmmeter
Scale
Used
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Relay 4 12
closed
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Direct
Resistance
Ohms
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
Probable Cause of
Incorrect Reading
Broken connection or wiring.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same
Same
Same
Same
Same
as
as
as
as
as
above.
above.
above.
above.
above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Misadjustment of relay 4 12 or burned
contacts.
Broken connection or wiring.
Same as above.
Same as above.
Section V
F i g u re 5 - 5
AN 1 6-40S CR624-2
TABLE 5 - 7.
RAC K CONTI N U ITY A N D RESISTAN C E MEASU REMENTS
From
To
Control
Positions
If Not
Normal
Ohmmeter
Scale
Used
Resistance
Ohms
( Conl' d ) .
Probable Cause of
Incorrect Reading
4 1 9, Term. 3
4 12, Contact No. 7
Direct
0
4 19, Term. 7
Receiver antenna jack,
inside pin
Receiver antenna jack,
outside pin
Transmitter antenna jack,
inside pin
Transmitter antenna jack,
outside pin
4 16, Center connector
4 12, Contact 1 , 4, 5
4 1 7, Term. 1 7
Ground
Ground
Direct
Direct
0
0
Misadjustment of relay 4 1 2 or burned
contacts.
Broken connection or wiring.
Broken or loose plug.
Direct
0
Broken connection or relay 4 12 misadjusted.
Direct
0
Broken or loose plug.
4 12, Contact No. 2
Direct
0
4 1 2, Contact No. 3
Ground
4 1 7, Term. 2
Direct
Direct
Direct
0
0
200
Broken connection or relay 4 12 misadjusted ;
burned contacts.
Same as above.
Misadjusted relay 4 12 or burned contacts.
Shorted low-voltage bus.
4 12, Contact No. 2
Ground
Armature
closed
o
0
o
o
Figure 5 - 5 .
R e ctifiers R A - 62 - S a n d R A - 6 2 - C-Tran sform er Termin a l Layout
5 - 25
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AN 1 6-40SCR624-2
Section V .
Para g raph 41-4g
f. RECTIFIER CONTINUITY AND RESISTANCE MEASUREMENTS.-The following table gives the
tinuity and resistance measurements for Rectifier RA-62-B or RA-62-C.
con-
.
TABLE 5-8. RECTIFIER CONTINUITY AND RESISTANCE MEASUREMENTS.
(Test Set-up: Rectifier RA-62-B or RA-62-C only-no connection to other units. )
From
Ref. No.
To
Term.
Ref. No.
Transformer
Receptacle
2
2
Receptacle
Receptacle
Receptacle
Receptacle
Receptacle
Receptacle
Receptacle
Receptacle
VT- 126-B
VT- 126-B
VT- 126-B
Receptacle
Receptacle
Receptacle
Receptacle
Receptacle
Receptacle
Across a-c input
Across a-c input
Across a-c input
Across a-c input
Across a-c input
Across a-c input
Transformer
Transformer
Transformer
Transformer
Transformer
Bias Choke
Plate Choke
Term.
Receptacle
Transformer
Transformer
Transformer
1
Bias Choke
5
H-V Choke
4
Bias Choke
8
Transformer
3
Transformer
5
Receptacle
Receptacle
1
Receptacle
1
Receptacle
1
Receptacle
1
Receptacle
2
receptacle contacts
receptacle COntacts
receptacle contacts
receptacle contacts
receptacle contacts
receptacle contacts
9
Transformer
11
Transformer
14
Transformer
16
Transformer
19
Transformer
1
Bias Choke
1
Plate Choke
9
5
Tes� Conditions
Operate relay
6
17
16
18
4
2
1
18
16
2
3
4
5
6
3
10
13
15
18
20
4
Operate relay
Selector 105
Selector 1 1 5
Selector 1 2 5
Selector 2 10
Selector 2 30
Selector 250
Tubes in socket
Tubes i n socket
Tubes i n socket
Tubes in socket
Tubes in socket
2
Resistance
(Ohms) ± l 0 %
80
1 5,000
Probable Cause of
Incorred Reading
Defective relay contacts, open choke.
Shorted capacitor, open resistor, defective relay.
Open resistors, defective relay solenoid.
Open wiring. *
Open transformer winding.
Same as above.
Open wiring.
Open wiring.
Open wiring, defective socket.
Open wiring, defective- socket.
Open wiring, defective socket.
Shorted wiring.
Shorted wiring, or capacitor.
Shorted . wiring.
Shorted wiring, or capacitor.
Open relay coil, open resistor.
Open resistor, shorted capacitor.
Open wiring, defective fuses.
Open wiring, defective fuses.
Open wiring, defective fuses.
Open wiring, defective fuses.
Open wiring, defective fuses.
Open wiring, defective fuses.
Open winding.
Open winding.
Open winding.
Open winding.
Open winding.
Open choke coil.
Open choke coil.
12,000
2,500
2,500
2,500
. 0
0
0
0
0
Open
Open
Open
Open
12,500
1 5 ,000
1.25
1.5
1.75
3.25
3.5
3.75
0.25
100
0.75
70
1.0
500
90
Some models do not in clude resistor in this circuit.
g. CONTINUITY AND RESISTANCE MEASUREMENTS FOR CONTROL BOXES BC- 1 l 75-A, BC-l3 12,
BC- l 3 14, and BC- l 3 l 3.-The following tables give continuity and resistance measurements for the control boxes:
•
TABLE 5-9.
From
Term.
Ref·
No.
222
222
222
11
7
7
222
221
221
222
222
222
22 1
221
22 1
7
3
8
6
Ref.
No.
CONTINUITY AND RESISTANCE MEASUREMENTS FOR CONTROL BOX BC- 1 1 75-A.
221
221
225-3
22 1
22'1
22 1
To
Term.
5
1
2
17
Test Conditions
"RADIO-PRESS-TO-TALK" switch
depressed
Relay operated
3
1
17
2
Relay operated
"RADIO-PRESS-TO-TALK" switch
depressed
Resistance
(Ohms) ± l 0 %
300
0
300
Open
0
0
90
Open
300
Probable Cause of
Incorrect Reading
Open relay coil 228.
Broken wire.
Open coil 228.
Relay stuck.
Broken connection or wiring.
Same as above.
Defective resistors 226-2 and 227.
Relay stuck.
Open relay coil 228.
5-27
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Section V
AN 1 6-405CR624-2
Paragra p h 4g-Tab l e s 5 - 1 0-5 - 1 1
TABLE 5·1 0.
CONTI N U ITY AN D R ES I STANCE M EA$U R E M ENTS FO R CO NTROL BOX BC·1 3 1 2.
Fro",
Ref·
No.
Term.
To
Ref.
No.
Term.
11
221
221
222
222
222
222
231
1
1
1
10
9
12
C
22 1
221
221
221
22 1
22 1
231
2
2 or
2 or
2 or
2 or
D
231
C
231
D
222
7
221
4
222
7
22 1
5
222
7
22 1
222
7
221
22 1
22 1
14
9
221
7
7
7
8
6
3
6
4
2 2 5·2
231
231
A
B
2 2 5·2
2 2 5 ·3
TABLE 5·1 1 .
Term.
5
13
2 2 5·2
221
From
5
5
5
9
2 2 5·2
o
o
Relay 2 2 8.operated
"SEND·REC." switch on "SEND"
"VOLUME" control, 2 32 maximum
clockwise position
"VOLUME" control, 2 3 2 maximum
counterclockwise position
Relay 2 3 0.4 energized, uLOCAL·
REMOTE· ' switch 2 2 3 on "REMOTE"
Relay 2 30·3 energized, "LOCAL·
REMOTE" switch 2 2 3 on "REMOTE"
Relay 2 3 0·2. energized, "LOCAL·
REMOTE" switch 2.2 3 on "REMOTE"
Relay 2 3 0·2 energized, "LOCAL·
REMOTE" switch 2 2 3 on "REMOTE"
"CHANNEL" switch 2 2 4 on "D."
"LOCAL-REMOTE" switch 2 2 3 on
"LOCAL"
"CHANNEL" switch 2 2 4 on "C."
"LOCAL·REMOTE" switch 2 2 3 on
"LOCAL"
"CHANNEL" switch 2 2 4 on "B:'
"LOCAL·REMOTE" switch 2 2 3 on
"LOCAL'"
"CHANNEL" switch 2 2 4 on "A."
"LOCAL·REMOTE" switch 2 2 3 on
"LOCAL"
Open
300
1 50
1 50
1 50
1 50
1 000
1·5
o
o
o
o
o
o
o
o
o
o
o
Probable Calise of
Incorrect Reading
Open relay coil 2 2 8 .
Broken wire.
Open coil of relay 2 2 8 .
Relay 2 2 8 stuck.
Broken connection or wiring.
Defective resistors 2 2 6 ·2, 2 27, and
233.
Relay 2 2 8 stuck.
Open coil of relay 2 2 8 .
Open coil o f relay 2 3 0.4
Open coil of relay 2 30· 3 .
Open coil o f relay 2 30·2.
Open coil of relay 2 30· 1 .
Defective potentiometer 2 3 2 .
•
.
Defective potentiometer 2 3 2 .
Poor contact o r failure of relay 2 30·4
to operate.
Poor contact or failure of relay 2 3 0· 3
to opetate.
Poor contact or failure of relay 2 30.2
to operate.
Poor contact or failure of relay 2 3 0· 1
to operate.
Open jumper.
Wiring, defective "CHANNEL" switch
. 2 2 4, or '.'LOCAL·REMOTE" switch
223.
Wiring, defective "CHANNEL" switch
2 24, or "LOCAL·REMOTE" switch
223.
Wiring, defective "CHANNEL" switch
2 2 4 , or "LOCAL· REMOTE " switch
223.
Wiring, defective "CHANNEl." switch
2 24, or "LOCAL·REMOTE" switch
223.
Defective o r open wiring.
Defective.
CONTI N U I TY A N D R E S I STAN C E M EAS U R E M ENTS FO R CONTROL BOX BC.1 31 4.
To
Ref.
No.
3 00
Open
90
8
5
Ref.
No.
3
3
1
17
221
o
"SEND·REC." switch on "SEND"
Relay 2 2 8.operated
17
221
2 2 5·2
Reristance
. (Ohms) � 10%
300
5
1
2
222
221
22 1
221
22 1
2 2 5· 3
221
222
222
222
222
222
222
221
Test Conditions
Term.
Test Conditions
2 14
C
· 2 14
D
2 14
C
214
D
214
214
212
B
A
2
212
2
212
212
2
212
9
"CHANNEL" switch 2 1 1 on "C"
2 12
2
212
12
"CHANNEL" switch 2 1 1 on "D"
212
7
212
11
"SEND.REC:' switch 2 1 0 on "REC."
212
7
212
11
"SEND.REC." switch 2 1 0 on "SEND"
"VOLUME" control, 2 1 5 , maximum
clockwise position
"VOLUME" control, 2 1 5 . maximum
clockwisl! position
"CHANNEL" switch 2 1 1 on "A�'
10
R evised 2. January 1 95 2
"CHANNEL" switch 2 1 1 on "B"
Remittance
(Ohms) � 10%
Probable Calise of
�ncorrect Reading
1 000
Defective potentiometer 2 1 5 .
1·5
Defective potl!ntiometer 2 1 5 .
o
o
o
o
o
o
Open
o
Open wiring.
Open wiring.
Open wiring, defective "CHANNEL"
switch 2 1 1 .
Open wiring, defective "CHANNEL"
switch 2 1 1 .
'
Open wiring, defective, "CHANNEL'·
switch 2 1 1 .
Open wiring, defective "CHANNEL"
switch 2 1 t .
Shorted "SEND·REC." switch 2 1 0 or
shorted wiring.
Open wiring or defective "SEND·
REC." s witch 2 1 0.
5 - 29
Section V
Figures 5-8-5-9
AN 1 6-40SCR624-2
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Control Box BC- J J 7 J -A-Wiring Diagram
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Section V
F i g u res 5 - 1 0-5 - 1 1
AN 1 6-40SCR624-2
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r r
I i/o�
r---I--vii RING
CODE
B
B f(
BR
G
0
R
W
Y
LEGEND
COL OR
BLUE
BU ICK
BROWN
G REEN
ORANGE
RED
WHITE
YELL O W
Figure 5 - l J -Conlrol S o x S C- 1 3 1 3-Wiring Diagram
5.- 3 1
Section V
AN
Paragraph 5 a-5a(2)(dl
1 6-405CI624-2
TABLE 5 - 1 2. CONTINUITY AND RESISTANCE MEASUREMENTS FOR CONTROL BOX B(- 1 3 1 3.
To
From
Term.
Re/.
No.
Term.
202
C
202
D
202
C
202
D
202
202
201· 1
201-1
A
B
20 1�2
201-3
20 1-2
20 1-2
Ref·
No.
"VOLUME" control, 203, maximum
clockwise position
"VOLUME" control, 203, maximum
counterclockwise position
"SEND-REC." switch
"SEND-REC." switch
200
200
on "REC."
on "SEND"
5. REPLACEMENT OF VACUUM TUBES AND FUSES.
Note
All tubes of a given type supplied with the
equipment should be used before employment
of tubes from general stock.
a.
REPLACEMENT OF TRANSMITTER VACUUM
TUBES.
Note
Instances may be encountered where a tube
reads tweiity or more milliamperes above an
average reading. If this is encountered, try
several tubes. Occasionally a tube is gassy
and this causes excessive plate current read­
ings. Never use gassy tubes.
( 1 ) Before replacing any vacuum tubes, become
familiar with the following instructions:
(a) Study the tube-heater circuits to become
familiar with the series-parallel arr1U1geoient used. This
is important to prevent the needless replacement of a
tube not "lighting" when the fault is in the other tube
in the same series circuit, A mistake often made when
servicing is to neglect to replace the r-f diode tube JAN6SS7 (VT-199) in its socket and, as a consequence, oscil­
lator tube JAN-6G6G (VT-198-A) does not light and
the crystal seems "dead." No other pairs of transmitter
tubes are interdependent in this manner. A puzzling
difficulty sometimes encountered, especially in the case
of tube JAN-S32 (VT- 1 i S ) , is that the tube filament
seems satisfactory when checked on a continuity meter
and lights (perhaps dimly) in the transmitter, but the
tube does not operate. This is known as an "air leaker"
tube. The envelope is filled with air at normal pressure
due to a crack or seal leak, and the filament still glows
without burning out. These tubes can usually be recog­
nized by the white oxidation inside the tube except, of
course, in the case of metal tubes which become very hot
because of the filament temperature alone. Sometimes
an "air leaker' , tube JAN-832 (VT- l lS) is a slow
leaker and goes through an ionization period in which
an arc strikes inside the tube. The great heat of this
arc often melts the plate and grids. Tubes destroyed
in this manner sometimes burn out the· associated r-f
choke and the modulation transformer. Occasionally,
5-32
Resistance
(Ohms) ± l0 %
Test Conditions
Probable Cause 0/
Incorrect Reading
1000
Defective potentiometer
203.
1-5
Defective potentiometer
203.
0
0
Open
0
Open wiring.
Open wiring.
Shorted switch 200 or wiring.
Open wiring or defective switch
200.
the metal tubes contain foreign matter which may be
"weld flash" loosened under prolonged vibration. This
causes interelectrode short circuits which are sometimes
difficult to find because of their temporary nature.
Exercise special care in handling tube JAN-S32 (VT1 1 8) because of its fragile structure_
(b) Insert or remove tubes from sockets by
pushing straight down or by pulling directly upward_
A vigorous rocking motion is definitely harmful. There
is sufficient vertical clearance on the ceramic base for
the pins, and tolerances of the pin diameters are care­
fully controlled.
Note
The final fraction of an inch of push is apt to
cause trouble since the length of the glass seal
around the pins may vary somewhat from pin
to pin. The longest glass seal 1imits the depth
to which the tube may be inserted into the
socket; therefore the tube :will "rock" around
the end if the longest seal is pushed any fur­
ther. Instances have been noted where a socket
contact has been rotated or distorted resulting
in a cracked tube when attempt was made to
use the socket. Investigate all cases where
the tube fits unusually hard because cracks may
form later from prolonged pressure strains.
( c) When observing tubes under operation, do
not confuse the fluorescent glow of the glass and getter
stain with the gas ionization glow in and around the
clements which is characteristic of a "soft" or gassy
tube. Gassy tubes are defective and should be replaced.
A gassy tube may be detected by the blue glow.
( 2 ) Test vacuum ' tubes JAN-832
monic amplifier) as follows:
(second har­
(a) Plug Test Set 1- 139-A into meter socket 1 7 1
o f a properly tuned transmitter (see fig. 4-1 ) and turn
the "METER SWITCH" knob ( 1 65 ) to position "2."
(b) Turn the set on by pushing channel "A"
button and allow a two-minute warm-up period.
( c) Record the reading on Test Set 1-1 39-A.
(d) Turn the equipment off by pushing the
"OFF" button on the control box. Remove the chassis
from the rack.
AN 1 6-40S C R 624-2
CAUTION
Use extreme care when removing or replacing
tube JAN-832 as the tube is easily damaged.
(e) Loosen the knurled thumbscrew on clamp
1 63 for the second harmonic amplifier tube JAN-832
in the bottom of the transmitter and turn the clamp
aside to make the tube socket accessible.
(I) Remove the tube by raising it directly up­
ward. Do not rock the tube when. removing it.
(g) Being careful to push straight down, install
a vacuum tube JAN-832, known to be in good condi­
tion, in the second harmonic amplifier socket.
(h) Replace the assembly in the case, turn on
the "A" channel, and after a two-minute warm-up,
retune the third and fourth tuning controls. Record
reading of Test Set I- 1 39-A.
(i) If the current recorded with the good tube
in the socket exceeds appreciably the original current,
replace the old tube, being careful not to damage the
new tube when inserting it.
(i) After inserting the tube in its socket, place
the clamp over the tube and tighten the thumbscrew.
(k) Connect the two output circuit plate clamps
to the plate terminals on top of the tube.
C A UTI O N
Do not cross the output circuit leads.
( 3 ) Test vacuum tube JAN-832 (power amplifier)
as follows:
(a) Plug Test Set I-1 39-A into meter socket 1 7 1
o f a properly tuned transmitter (see fig. 4-1 ) and turn
the "METER SWITCH" knob ( 165 ) to position "3."
(b) Turn the set on by pushing channel "A"
button and allow a two-minute warm-up period.
(c) Record the reading Test Set 1-1 39-A.
(d) Turn the equipment off by pushing the
"OFF" button on the control box and remove the
chassis from the case.
(e) Loosen the four Dzus fasteners from the
end plate located on the right side of the transmitter
chassis (see fig. 4-5) and remove the plate.
(I) Remove tube JAN-832 by pulling straight
up. Do not rock the tube. Be sure to remove the
plate terminal leads and reconnect them when the
tube is replaced .
CAUTION
Do not cross the tank circuit leads.
(g) Being careful to push straight down on the
tube, install a tube JAN-832 known to be in good
condition in the power amplifier socket.
(h) Replace the assembly in the case, press
channel "A" pushbutton, and after a two-minute
warm-up retune the third and fourth tuning controls.
Record the reading on Test Set I-139-A.
(i) If the current recorded with the good tube
Para g ra p h
Section V
5 a(2)le)-6al 1 )1e)
in the socket exceeds appreciably the original cur­
rent, replace the old tube.
0) Replace the end plate, making certain that
the mycalex clamp on its side surface holds the tube
JAN-832 firmly in its socket.
(k) Remove the remaining tubes one at a time
and test in a tube checker. Replace all defective tubes.
b. REPLACEMENT OF RECEIVER VACUUM
TUBES.
( 1 ) Remove the four red mounting screws holding
the receiver to the rack.
( 2 ) Lift the receiver side of the rack while press­
ing the top of the receiver down with the thumbs. Lift
the rack away from the receiver.
( 3 ) Remove one tube at a time, test in a tube
checker, and replace the defective tubes. Replace imme­
diately any tube showing signs of oxidation.
(4) Remove the tube securing clamps when re­
placing tubes JAN-9002 and JAN-9003.
( 5 ) Fasten these clamps securely after the tubes are
replaced.
c.
REPLACEMENT OF RECTIFIER TUBES.
( 1 ) Remove the six screws holding the front panel
to the frame of the case.
( 2 ) Remove the front panel.
( 3 ) Loosen the band around the base of the tube
which holds the tube snugly in the socket.
(4) Lift out the defective tube and replace with
a good one, being sure that the base bands are fastened
tightly.
d. REPLACEMENT OF RECTIFIER FUSES.-Recti­
fier RA-62-B or RA-62-C is protected against overload
by two 3-ampere, 2 50-volt fuses. These fuses are located
in a container attached to the control panel at the left
of the "OFF-ON" switch. To replace the fuses, pro­
ceed as follows:
( 1 ) Loosen the captive slot-head nut with a screw
driver which allows the hinged fuse container cover to
swing outward.
( 2 ) Remove the defective fuse and replace it with a
spare fuse from the spare fuse box ( similar to the fuse
box) located on the outside of the front panel.
6. SPECIAL MAI NTENANCE PROCEDURES.
a. DISASSEMBLY.
( 1 ) TRANSMITTER.
(a) Loosen the four large Dzus fasteners, lo­
cated on the sides of the case.
(b) Grasp the rack by its recessed handle and
lift the rack ( together with the transmitter and re­
ceiver) out of the case. Set it down, control panel
uppermost, on a flat surface. Be careful not to set
the equipment on a screw driver, pliers, or other tools.
(c) Loosen the Dzus fasteners pinning the trans­
mitter and receiver covers to the center cover. Lift the
covers slightly and slide them away from the top of the
transmitter and receiver.
5 -33
Secti o n V
Para g ra p h 6 a l 1 IIdl-6a(4Ib
AN 1 6-40SCR624-2
(d) If the equipment has been turned on and one
of the frequency shifter slides is engaged (i. e., one of
the four channels has previously been selected) press
the channel release push button on Rack FT-224-A
which releases the frequency shifter slide previously
actuated. Turn the equipment off.
(e) If the rack is disconnected from a power
source, disengage the shifter slides by carefully operat­
ing the armature of the ratchet motor by hand.
CAUTION
Damage to the equipment will result if all
channel slides are not released prior to remov­
ing the transmitter from the rack.
(f) Remove the four red mounting screws fasten­
ing the transmitter to the rack.
(g) Lift the transmitter side of the rack slightly
while pressing the top of the transmitter proper down
with the thumbs.
(b) Lift the rack, together with the receiver,
away from the transmitter.
( 2 ) RECEIVER.
(a) Remove the four red-painted receiver-mount­
ing screws.
(b) Lift the receiver side of the rack while press­
ing the top of the receiver down with the thumbs.
Lift the rack away from the receiver.
Note
The r-f and oscillator sections of the receiver
may be removed as a complete unit, or the
oscillator section may be removed separately.
( c) Unsolder the black, white-blue, red, and
brown leads from the oscillator section terminal board.
(See fig. 4-14.)
(d) Unsolder the black-white-green, the red­
white, the two red leads, and the two brown leads from
the r-f section terminal board. (See fig. 4-12.)
( e) Unsolder the blue lead from terminal two
of first i-f transformer 291.
(f) Unsolder the grounding lug.
(g) Remove the r-f oscillator grounding strap.
This strap provides a good ground and ties both the
r-f and oscillator sections to a shield in the receiver.
The r-f and oscillator section cannot be removed unless
this ground strap is completely free of the shield.
(b) Loosen the receiver tuning-control lock nuts
(see fig. 4-9) and set both receiver tuning controls at
the alignment mark (high frequency) above the 1 56megacycle division on the calibration plate.
(i) After softening the glyptal with glyptal thin­
ner, acetone, or heat, insert a setscrew wrench in the
holes provided in the rear of the receiver (see fig. 4-9j
and loosen one set screw in each of the two variable
capacitor couplings. Setscrew wrenches are provided
in the special tool set (part of Test Equipment IE-19-A
or IE- 1 2-A) .
5 -34
0) Set both receiver tuning controls at the
alignment mark (low frequency) below the 100 mega­
cycle division on the calibration plate and repeat the
procedure of subparagraph (i) above.
(k) Remove the two mounting screws (one near
the channel "D" crystal identification plate and one
next to the 286 stencil mark) of the crystal-selector
switch 286 and draw the switch away from the fre­
quency shifter mechanism, thus disengaging the switch
arms from the shifter slides.
WARNING
Do not remove the nuts on top of switch 286
(see fig. 4-7), as this may cause the switch to
come apart.
(l) Remove the four frequency-shifter mount­
ing screws (see fig. 4-7) and remove the frequency
shifter-mechanism.
( m) Remove the six screws ( three on the right
and three on the left side of the r-f and oscillating
assembly) which secure the assembly to the receiver
chassis. The three screws on the right side of the
assembly are shown in figure 4- 1 1 .
(n) Lift the r-f and oscillator assembly out of
the receiver.
(0) To remove the oscillator section only, fol­
low the procedure of paragraph 6a ( 2 ) (a), (b), (c) J
(g), (b), (i) and 0) [ in (i) loosen only the screws in
the coupling for the variable capacitor 2 1 7A and B] .
(p) Remove the oscillator section mounting
screw and the two mounting nuts.
(if) Pull the oscillator section away from the
tuning control and lift it out of the receiver.
( 3 ) RATCHET MOTOR.
(See fig. 4-9.)
IMPORTANT
Do not tamper with the ratchet motor unless
it is absolutely necessary.
(a) Remove the small screw (next to the posi.
tioning spring) which connects the ratchet motor to the
L-shaped brackets on top of the actuating slides.
(b) Remove the four motor-mounting screws on
the bottom of the rack.
( c) To detach the motor from the rack, unsolder
all the wires attached to the motor.
(4) RECTIFIER RA-62-B OR RA-62-C.-To gain
access to the interior of the rectifier, proceed as fol­
lows:
(a) Remove the six screws which hold the front
panel to the frame of the case and take off the front
panel.
(b) Remove the screws which hold the base to
the case and take off the base.
b. CLEANING AND LUBRICATION.-The fol­
lowing tables give information on the cleaning and
lubrication of the major assemblies of this radio set.
AN 1 6- 405CR624-2
TABLE 5 - 1 3 .
Maior Assembly
Bearing surfaces of shifter P-S-661 solvent or carbon tetra­
Transmitter­
slides; actuating slides,
chloride.
receiver frequency
tracks and spacers
shifter mechanism
Rack FT-244-A
Ratchet Motor
Motor arms, ratchet
wheel ; pawl and pawl
stop; hinge assembly
Secti o n V
6c( 1 )-6dlUd
CLEAN I N G CHART.
Type of Cleanser
Part
Paragra p h
P-S-66 1 , solvent or carbon tetra­
chloride.
Cleaning
Period
1000 hours
1000 hours
Procedure
1. Remove transmitter and re­
ceiver from the rack to gain
access to the frequency
shifter mechanisms.
2.
Clean and lubricate accord­
ing to instructions in the fol­
lowing lubrication chart.
1.
Remove transmitter and re­
ceiver from rack to gain ac­
cess to die ratchet motor.
2.
Clean and relubricate ac­
cording to the instructions
in the following lubrication
chart.
Transmitter­
receiver assembly
Telephone type relays
Flat toothpick dipped in carbon 1000 hours
tetrachloride or contact burnishers, consisting of a thin flexible
metal strip slightly roughened by
sandblasting or etching (or made
of soft metal such as nickel · silver
milled like the edge of a coin.
Burnish contacts of relays.
Radio receiver
Squelch relay
Clean as directed for the telephone- 1000 hours
type relays.
Burnish controls of relay.
Rack FT-244-A
Positioning switch
Clean as directed for the telephone- 1000 hours
type relays.
Burnish contacts of relay.
Rack FT-244-A
Motor interrupter
contacts
Thin single-faced contact or magneto point file with one side
ground to a thickness of .0 10 to
. 0 1 5 inch or fine sandpaper.
TABLE 5 - 1 4 .
Major Assembly
1000 hours
Remove all silver deposited on
the tungsten using the sug­
(Clean only if
buildup of silver gested file. Further dean by
or tungsten con- dressing with fine sandpaper .
tact is excessive.)
LUBRICATION CHART.
Part
Type of
Lubrication
Lubrication
Period
50 hours
Transmitter and
receiver frequency
shifter mechanism
Cross arm pivot bearings, Cross arm slots
and large bushings for transmitter and re­
ceiver actuating slides. Cams and spacers
bearings surfaces of shifter slid •.
AN-06A oil
Transmitter and
rec.!iver frequency
shifter mechanism
Heads of shifter slides. PiA and slot bear­
i llS surfaces at each end of cross arms at
pivoting point.
AN-G-3A
grease
18.,
Rack FT-244-A
ratchet motor
Teeth €If ratchet wheel.
AN-G-3A
grease
100 houfS
AN-06A oil
50 hO\Jrs
Ratchet wheel armature assembly and shaft.
Armature hinge. If pawl spring is attached
to the armature by a hinge, and spring,
lubricate at the hinge and point of contact.
6.
_JUSTMENT AND REASSEMBLY.
( 1 ) R-F AND OSCILLATOR ASSEMBLY.
fr;,) Reassemble and reinstall the r-f and oscil­
lator assemblies, reversing the procedure given in para­
g.caph 611, this section.
See that the cryst al switch arms engage the
pins of fIl"e frequency shifter slides.
CAUTION
hours
Procedure
Remove transmitter-receinr
from case and rack to gain
access to the frequency shifter
mechanism.
Remove transmitter-receiver
from case and rack to gain
access to the frequency shifter
mechanism.
Remove the rack from the trans­
mitter-receiver to gain access
to the ratchet motor.
( b) Set the receiver tuning controls at the dial
mark below the 1 00-megacycle division. With the re­
ceiver tuning controls in this position, the rotors of
the r-f and oscillator capacitors 2 1 6A, B, and C, and
2 1 7A, and B, respectively, should be fully meshed with
their respective stators.
( c) If this is not the case, loosen the lock nuts
and turn the tuning controls to the alignment ma rk
(high frequency) above the 1 56-megacycle calibration.
5-35
Secti o n V
Paragra p h 6cl1 )(d)-6d3)(o)
AN 1 6-40S C R624-2
Insert a set-screw wrench into the holes provided in
the rear of the receiver chassis and loosen one set­
screw in each capacitor coupling shaft. (Setscrew
wrenches are provided in Test Equipment Set IE-19-A
and IE- 12-A.)
(d) Turn the tuning controls to the alignment
mark (low frequency) below the lOO-megacycle calibra­
tion division. Loosen the other setscrew in each ca­
pacitor coupling shaft. With the tuning controls accu­
rately set on the low frequency alignment mark, com­
pletely mesh the capacitor plates and tighten one set­
screw in each coupling shaft after applying glyptal to
the setscrew threads.
( e) Turn the tuning controls to the high-fre­
quency end of the band, apply glyptal and tighten the
remaining setscrews.
( 2 ) FREQUENCY SHIFTER MECHANISM.
(tt) Straighten the frequency shifter slides if
necessary.
( b) Check the torque of each cam shaft when
the shifter is mounted on the transmitter or receiver.
Check with a torque checker for not more than two
inch-ounces, and make certain that the clip will re­
position the shaft when the clip has just been un­
seated.
(c) If the frequency shifter mechanism has been
disassembled, adjust the eccentric screw and bushing
pivoting the upper cross arm group. Keep the arrow
on the head of the screw and on the bushing pointing
in the same direction, and adjust the pair to operate
the shifter slides a distance of 2 1 /32 inch. (The gap
between the receiver shifter actuating slides and receiver
shifter slides will be approximately 1 /32 inch in the
released position.)
(3) RATCHET MOTOR.
(tt) If the trouble in the ratchet motor is purely
of an electrical nature, see paragraph 4e, this section,
and make continuity tests of the circuit in question.
( h) If the motor has been disassembled for re­
pairs or adjustments, assemble the armature hinge and
the associated adjustment screw but do not tighten them
securely.
. Note
In all cases where the assembly of screws does
not involve the use of lockwashers, cement the
threads with purple glyptal. Avoid excess
glyptal.
(c) Locate and securely tighten the solenoid as­
sembly with the dimensions from the center of the
open end to hinge 765 .
(d) Before assembling the armature, lubricate
the armature hinge and the pole faces with AN-G-3A
grease.
( e) Be sure that the top screw and lock nut are
in place. Drop the upper core into the open end of the
solenoic and work the armature in place by starting
the armature in slightly sideways in order to clear the
armature stop screw.
5-36
(j) At the same time the armature is being as­
sembled in pla-ce, guide the threaded stud of the upper
core into the hole in the center of the armature. Place
the lock nut on the stud and tighten securely after
threads have been glyptaled.
(g) Assemble the armature springs and tem­
porarily tighten the screws.
( h) Adjust the hinge to allow the cores to rest
squarely together in the energized position by adjust­
ing the height of the hinge until the armature is
parallel with the edges of the sides of the motor frame.
Permanently secure the armature hinge and adjusting
screws at this time.
(i) Adjust the armature stop screw to provide
.058 to .060-inch movement of the armature as gauged
at this point with a thickness gauge. Secure the nut
tightly after application of glyptal to the threads of the
screw.
0) Adjust the armature spring tensions to pro­
vide a load of 6-3/4 pounds measured in line with the
pawl spring. Measure this tension with a push spring
scale pressed against the pawl spring perch on the
armature. The tension reading should be that required
to j ust start the armature moving.
Note
In the absence of a push scale, make the ap­
proximate adjustment by setting the spring
tensions to j ust allow the armature to pull in
with 1 . 1 ampere doc passed through the sole­
noid coil. Divide the spring load approxi­
mately evenly between the two springs.
(k) Assemble in place but do not tighten the
pawl .stop block and ratchet-wheel positioning-spring
assembly.
(1) Assemble the ratchet wheel and arm assembly
.
and shaft. Lubricate with AN-G-3A grease.
(m) Permanently set the positioning spring as­
sembly to engage the fourth or fifth tooth behind the
pawl and bear against it with approximately two to
four ounces pressure. To insure the most satisfactory
operation, make the lengthwise adjustment so that the
over travel of the pawl and the end play at the posi­
tioning spring are approximately equal.
(n) Set the pawl stop block up to within a few
thousandths of an inch of the back of the pawl in the
unenergized position. This setting should be about as
close as the eccentricity of the ratchet wheel will allow.
This may be j udged by stepping the wheel around and
determining that at no point is the back movement of
the armature limited by the pawl stop block instead of
the stop screw. This stop block is used primarily to
limit the overshooting. When the armature is in the
unenergized position it will not be possible to rotate
the ratchet wheel and arm assembly more than a quarter
of a tooth.
( 0) Mount the interrupter switch assembly and
securely tighten the screws after the assembly has been
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Section V
Paragra p h 6c(3) (p)-6c15I1g)
AN 1 6-40S C R 6 2 4 - 2
aligned with the interrupter adj usting screw. Set this
screw to cause the interrupter contacts to open approxi­
mately 0.006-inch with the armature in the fully ener­
gized position. The exact adjustment of these contacts
can be made only with the motor operating under a
normal load and is reserved until the final check in
the rack. The contact spring tension measured at the
contacts should be from 3 to 6 ounces.
(p) Check the running of the motor. Connect
a two microfarad capacitor across the solenoid coil
and connect the interrupter contacts in series with the
. coil and 12 volts from a storage battery. The motor will
operate smoothly if the adj ustments are correct. The
adjustment of the interrupter contacts will be found
to have the most noticeable effect on running. Set
these contacts at this time to give the best performance.
( q) Install and adjust the positioning switch
asscmbly. Mark a reference line at the radial face of
the tooth parallel to the straight side of the upper motor
arms (which falls between marks A and B on the side
of the ratchet wheel ) . Count off ten additional faces
in a clockwise direction and make a second reference
mark at the tenth face. Step the ratchet wheel around
until the straight side of the pawl tooth aligns with
the second mark. Adjust the positioning switch as­
sembly to allow a clearance of approximately 0.0 10inch to 0.0 1 5 -inch between the bakelite fingers and the
arms as they are cleared.
(r) Step the ratchet-wheel assembly around 2 2
tceth and adjust the lateral positioning of the switch
assembly to allow a bakelite finger to j ust rest against
the next motor arm to be engaged. One step further
should open this switch and it should remain open
for one additional step. One step beyond this should
again close this switch, and the clearance between the
motor arm and the bakelite finger should not exceed
0.0 1 5 inch.
(s) If the motor arms are spaced exactly 90 de­
grees and the ends of the bakelite fingers are properly
aligned, all four motor arms should open the position­
ing switches for two positions only and should clear
the fingers of the switches by not more than 0.01 5-inch
when again released. Determine this by trial and make
adjustments accordingly.
(4) ASSEMBLY AD ADJUSTMENT OF
RATCHET MOTOR IN RACK FT-244-A .
(a) Install the motor in the rack with the mount­
ing screws sufficiently loose to allow proper positioning.
With later production rack assemblies, the large clear­
ance hole for the ratchet gear shaft has been omitted,
and in its place is a hole j ust large enough to receive
the proj ection of the gear shaft. This hole is placed ac­
curately with respect to the transmitter mounting holes
in the rack. This automatically maintains the ratchet
gear center in a position to provide 2 1 /32 movement
of the frequency-shifter slides.
( b) Pivot the motor about this point until a
slide operated by a motor arm is just released and the
clearance between the slide' head and the motor arm at
5-38
the time o f release is j ust sufficient t o allow release
when the slide is cocked sideways to cause this clear­
ance to be at a minimum.
( c) Use a 0.002-inch or 0.003-inch gauge to
check this clearance between the closest pair of arms and
slides.
( d) When it is determined that the closest com­
bination of arms and slides just clear when the slide is
cocked sideways, secure the mounting screws with the
motor in that position.
N ote
The closest pair of arms and slides must clear
by at least o.OOI-inch and the clearance between
the pair of arms and slides having the greatest
clearance must be less than 0 .030 of an inch.
( e) No further positioning is required.
( 5 ) ADJUSTMENT OF RATCHET MOTOR ON
EARLIER PRODUCTION RACK
ASSEMBLIES.
(a) Actuate the motor armature until a slide
has j ust been released . This will assure that all the
slides are released.
(b) Place the rack assembly on a transmitter
unit and check the clearance between the actuating slides
and the slides of the shifter unit. This clearance
should be approximately 1 /32 inch. For a similar
check see that a shifter slide is moved in for a dis­
tance of 2 1 /32-inch when the motor is operated to a
point where a positioning switch first opens.
( c) Check the operation of the slides on the re­
ceiver side of the rack. The shifter actuating ends of
these slides in the engaged position, should measure
3-3/4 inches from the edge of the receiver and should
measure 3- 1 / 1 6 inches from the receiver edge with the
slides in the engaged position. If adjustment is re­
quired, adjust the eccentric screw which pivots the
crossar m s on the receiver side of the rack.
(d) Check the adjustment of these slides by
placing the receiver in the rack and checking to see
that the clearance between the actuating slides and the
shifter slides is approximately 1 /32-inch in the released
position. For a similar check, ascertain that the shifter
slides are operated at a distance of 2 1 /32,inch when
positioned by the motor.
( e) By visual inspection and manual operation,
check to see that when any motor arm maintains a
positioning switch in its second open position, the oppo­
site motor arm has j ust released the slide held in the
first open position. It should clear the slide head
from 0.005 to 0.0 1 5 inches preferably by as small an
amount as will allow unfailing release of the slides in
the four desired positions.
(f) Rotate the motor-arm assembly and check
all four positions to ascertain which arm comes closest
to not clearing the associated slide head.
(g) Use a 0.002-inch or 0.003-inch shim stock,
if desired, to see that when the opposite end of this
AN
Section
sl i de is co cke d s i dew ay s to cause the sli de head to be
ne ares t the motor arm, the clearance is just sufficient to
allow release.
(b) Check to see that the positio n ing of the
a radius line from the ratchet wheel
a ss e mbl y s h aft center pas sin g through the radial face
of an arm is parallel to a sl i de in the release d po sitio n.
(i) See that a ll bearing surfaces of the rack
motor is such that
fre quen cy shifter mechanism are lubricated with AN-
0 - 6a
oil.
(a)
(6) MOTOR INTERRUPTER CONTACTS.
Mount the tran sm itte r and
receiver
on the
rack and connect the e qu ipme n t to a regular
power
sup pl y or a 12-volt storage b at te ry .
(b)
Note that the motor
P a ra g ra p h s
1 6-40S CR624-2
o perates s atisfactorily
while the heavy i n terrupter contact spring is Hexed in
and out o ver a certain range. Set this h eavy contact
(8)
TELEPHONE TYPE RELAYS.
(a)
D o not
attempt adjustment of the telephone­
rel ays as the a dj us tment made in the factory is
n ormall y perm anen t .
( b) Burnish or po l ish the contacts with a Hat
toothpick d ipped in carbon tetrachloride or with a
co ntact burnisher consisting of a thin, Hexible metal
s trip s l ightly roughened by s an d - bl astin g or etching
( or made of soft metal such as nickel, silver, milled
like the edge of a coin) . Do not use s andp aper, crocus
cloth, or even a contact file an d provi d e pressure for
the work only by the closed co ntacts.
type
OVER-ALL PERFORMANCE TESTS FOR
RADIO RECEIVER·TRANSMITTER ASSEMBLY.
7.
a. GENERAL.-If the opera tion of the equipment is
unsa tisf actory or if m ajor repairs or adjustments have
been made, check the
performance
of the equipment
in
figures
agree approxi­
characteristics
sp ri n g outward to just within the p oi n t which causes
a noticeable ch an ge in motor performance. This a d ­
accordance with the fol l owing procedu re.
justment allows the spri n g to
m atel y
be Hexed inwatd more
than outward before erratic perform ance results and
al lo w a more n early op timum setting f o r e xt re mely
l ow temperatu re .
Note
(d) O p e ra te the ratchet motor fo r a period of
from 15 to 20 minutes after assembly of Rack FT244-A to the receiver and transm itte r. At the end of
the run, c areful ly i n spect the ratchet motor and rack
fo r loose parts and check ad justme n ts of the ratchet
m otor.
( 7 ) SQUELCH RELAY.
(It) If proper operation of the squelch relay
cannot be obt a in ed , check the spa cing between the H at
and
the armature.
This
and .003 inch.
spacing
should
be
. (b) A d j ust the sp ring ten sion to th e point at
which the relay closes when a current of app roxim ately
4 m illi amp ere s Hows through the coil. When properly
adj usted, the squelch rela y should open and close with
(for exampl e,
3.8 m il l iamperes ) .
close at 4 m ill iamperes ,
a coil-current differential of not more
ampere
t h an
0.2 milli­
open at
( c) Make certain th a t the armature spring does
not rub aga inst any portion of the r ela y frame. Erratic,
unde p endable op e ration will result if th ere is exce s siv e
play
in the
a rm atu re pivot bearings .
Note
An electronic type audio squelch in Radio
Receiver BC-624-C rep l aces the relay squelch
u sed in Radio R ec e ive r BC-624-A and BC624-AM.
s
the
normal
perf orm ance
The
in the following tables but in no case should they
be below the minimum performance characteristics.
b.
STANDARD
conditions for all
and pawl bearing surfaces with AN-G-3a grease.
contact
given
result of these tests should
as a
with
TEST
CONDITIONS.
p erfo rma nce
mitter
- Unless
standard test
tests of Radio Receiver
BC-624-A, BC-624-AM, or BC-624-C
( c) Ge n erousl y lubricate the ratchet gear teeth
b etwee n .00 1 5 inch
obtained
otherwise specified, maintain the following
The spee d of the motor under normal load at
room temperature should be at least 28 revol u ­
tions p er minute at 12 volts .
V
6d5Hhl-7b C l 0)
and Radio Trans­
BC-625-A or BC-625-AM.
( 1 ) INTERCONNECTING
CORDS. -
COnnect
tem­
104° F) .
( 3 ) HUMIDITY.-The humidity should be 25 per­
cent to 90 p ercent.
( 4 ) ATMOSPHERIC PRESSURE.-The press u re
should be normal.
( 5 ) VIBRATION.-There should be n o vibration.
the tra n smitter-receiver assembly for
operation.
. ( 2 ) TEMPERATURE.-Prevailing
pe ratu re should be 20 ° C to
40·
ambi e nt
C ( 60 · F to
( 6) WARM-UP PERIOD.-The warm-up period
should be not l ess
(7)
than
th e receiver,
a
five
minutes.
50-ohm non-inductive
PHANTOM
( DUMMY)
ANTENNA.-For
resistor ( including
CD-
s i gnal - ge nerator output ci rcui t ) in series with COrd
in d uctive power resistor in series with a th erm omilli­
ammeter must be conne cted to the end of a 5-foot Cord
477
(5 feet long) .
CD-477.
(8) D-C
For the transmitter, a 50-ohm non­
INPUT VOLTAGE.-See that
the doc
volt ages are 13 volts for heater, minus 150 volts for
(9) SQUELCH CIRCUIT AND AUDIO LEVEL
CONTROLS.-Set the squelch circuit "RELAY" con­
Bias, and 300 volts for B+ .
trol
This
(see fig. 4-17)
in the extreme clockwise position.
rend ers the squ elch circuit inoperative. Set the
"AUDIO" l ev el control in the extreme clockwi se po s i ­
tion for maximum output.
( 10) OUTPUT LOAD (RECEIVER AUDIO) .­
Non-reactive load
of
300 ohms ( G.R. output meter) ,
yell ow lead connected t o terminal
No.
6 o f audio
5-39
Section V
Paragra p h 7&1 1 1 )-7(2(f)
A N 1 6-40SCR624-2
transformers 296 on Radio Receiver BC-624-A, BC624-B, BC-624-C, BC-624-AM or to terminal No. 4 of
transformer 200 in Radio Receiver BC624-C.
( 1 1 ) POWER AMPLIFIER LOADING.-Unless
otherwise specified, resonate and load the power ampli­
fier so that with the transmitter "METER SWITCH"
in position 3, the 0- 1 ma doc test milliammeter reading
is 0.65 . When maximum antenna current is obtained
at values of plate current lower than 0.65 (on miIli­
ammeter scale) , tune the transmitter and adjust for
maximum antenna current.
( 1 2 ) STANDARD MODULATED SIGNAL.­
This signal should be 30 percent at 400 cycles.
( 1 3 ) STANDARD OUTPUT.-The output should
be 1 0 miIliwatts, combined signal and noise.
( 14 ) ADJUSTMENT OF RECEIVER OUTPUT.­
Because of the high frequencies involved, take special
care with the various cables associated with the test
set-up. Before any measurements are made on a new
set-up, dress the cables so that with the signal-generator
attenuator set at zero, the receiver output ( except for
noise) is actually zero.
( 1 5 ) CRYSTAL SELECTION.-For test purposes,
space the four channels equally over the range of 1 001 5 6 megacycles. Refer to paragraph 9d( 3 ) (c), this
section, for instructions on choosing receiver crystals
for desired frequencies and for instructions on receiver
channel alignment. Make all measurements with a
Ferris Microvolter Model l SC (or equivalent) . It is
not possible to use Signal Generator I-96-A for this
purpose.
c. METHODS OF MEASUREMENT.-To make per­
formance tests, proceed as follows and record results
on forms similar to the tables in the following para­
graphs.
( 1 ) SELECTIVITY.
(a) Remove the receiver transmitter and rack
from the case and connect the output of a Ferris l SC
signal generator (or equivalent) to the control grid of
the receiver mixer tube JAN-9003 and the frame of
the r-f unit. Use the shortest possible leads.
(h) Place the equipment in the receive position.
(c) Set the signal generator for a 1 2-megacycle
signal, 30 microvolts output. With a General Radio
(or equivalent) output meter connected to the audio­
output terminals of the connector panel, adjust the sig­
nal-generator tuning control for maximum receiver out­
put and then adjust the receiver "AUDIO" control for
10 milliwatts output.
(d) Increase the signal generator output to 60
microvolts and adjust the frequency control above and
below resonance ( 1 2 megacycles) to find the frequencies
required to give 10 milliwatts receiver output. Do not
change the receiver tuning-control settings. The total
bandwidth is the difference in kilocycles between the
signal-generator settings above and below resonance.
(e) Repeat for. 1 0, 100, 1000, and 10,000 times
30 microvolts output and record the total bandwidths.
5 -40
SELECTIVITY
Test
Frequency
Input in
Microvolts
Bandwidth
Normal
Minimum Maximum
12 megacycles
30
Above
Below
50
60
kilocycles
kilocycles
87
96
129
1 36
1 79
. 222
x2
1 10
60
kilocycles
kilocycles
1 30
kilocycles
181
200
xlO
265
290
176
x 1000
355
390
238
x 10,000
460
490
( 2 ) NORMAL SENSITIVITY.
(a) Place the transmitter-receiver and rack inside
the case and connect the standard signal generator
( Ferris lSC ) through the phantom ( dummy) antenna
and Cord CD-477 to the antenna input socket 4 1 6 lo­
cated on the rack.
(h) Connect the reCeiver audio output to the
output-power meter. Set the meter impedance at 300
ohms. For a 300-ohm receiver-output impedance, con­
nect the yellow wire to terminal 6 of the receiver
audio-output transformer 296 for Radio Receiver BC624-A or BC-624-AM. For Radio Receiver BC624-C,
connect to terminal 4 of transformer 200 for the 300ohm tap. (Terminal 5 is the 4OO0-ohm tap.)
(c) Set the signal generator at the desired test
frequency. Set the output at approximately 5 micro­
volts. Set the receiver "AUDIO" control at the extreme
clockwise rotation position.
(d) Tune the signal generator for maximum
receiver audio output. Turn the modulation off* and
adjust the receiver "AUDIO" control for 1 milliwatt
noise output.
( e) Turn the modulation on again and adjust
the signal generator output for 10 milliwatts audio
output (signal plus noise) .
(f) Continue to adjust the receiver "AUDIO"
control and the signal generator output until 10 miIli­
watts audio output is obtained with the modulation on
and 1 milliwatt with the modulation off, the receiver
input and gain remaining constant. Record the signal
generator output setting. This is the sensitivity ex­
pressed in microvolts.
NOTE :
With the
modulation
turned oft,
it
is necessary
to slightly
retune the 1Se signal generator for maximum receiver audio output since
•
this generator shifts frequency slightly when the .modulation i s
on or oft, particularly at frequencies above 125 megacydes.
turned
AN 1 6-40S CR624-2
AUTOMATI C GAIN CONTROL CHARACTERISTIC
RECEIVER NORMAL SENSITIVITY
Sensitivity
Test Frequency
100
megacycles
3.4
microvolts
6
microvolts
124
megacycles
2.6
microvolts
6
microvolts
140
megacycles
3. 1
microvolts
6
microvolts
1 56
megacycles
3.4
microvolts
6
microvolts
( 3 ) IMAGE-FREQUENCY REJECTION.
(a) Operate the receiver in accordance with the
instructions given in paragraph 9, this section. For a
given test frequency, follow the same instructions given
in paragraph 9, this section, for measuring normal
sensitivity. Record the signal generator output.
(b) Adjust the signal generator frequency to the
image frequency ( signal frequency minus twice the in­
termediate frequency, or 24 megacycles) .
(c) Increase the signal generator output until
1 0 milliwatts audio output is obtained from the re­
ceiver. Record the output.
(d) Record the image rej ection ratio as the
microvolts obtained in ( c) divided by the microvolts
obtained in (a) . Repeat for each test frequency.
Image-Re;ection Ratio
Test Frequency
Normal
20
0
50
1.7
Maximum
0
100
1.8
1,000
3.9
10,000
5.4
100,000
5.8
6
12
(a) Operate the receiver according to the in­
structions given in paragraph 9, this section . Use a
channel frequency of 100 megacycles and set the receiver
"AUDIO" control at maximum ( extreme clockwise
position) .
( 5 ) AUDIO-FREQUENCY POWER OUTPUT.
(b) Record the microvolts input necessary for
75 milliwatts and 300 milliwatts receiver out�ut.
RECEIVER A - F OUTPUT POWER
Test
Frequency
RECEIVER INPUT
Receiver
Output
Maximum
Normal
100
megacycles
75
milliwatts
3.7
microvolts
100
megacyCles
300
milliwatts
7.7
microvolts
7.5
15
microvolts
microvolts
Minimum
Normal
1 56
megacycles
5,000
1,000
148
megacycles
14,000
3,000
140
megacycles
24, 100
lO,OOO
(a) Operate the receiver in accordance with the
instructions given in pi1ragraph 9, this section. Use
channel frequency of 100 megacycles.
(4) AUTOMATIC GAIN CHARACTERISTIC.
( b) Set the signal gener.tor output at 20 micro­
volts, 30 percent modulated. Adjust the signal genera­
tor tuning dial for maximum receiver output.
( c) Increase the signal generator output to 100
microvolts and adjust the "AUDIO" control for 100
milliwatts receiver output.
(d) Reset the signal generator for 20 microvolts
output in milliwatts. Repeat for each receiver input
listed in the table below.
( e) Calculate the output in decibels, referring
to the output for 20 microvolts input
Output (db)
Input
(Microvolts)
Minimum
Normal
Section V
7(3)-7(6)(d)
Pa ragra p h
as
zero level.
(6) RADIO TRANSMITTER BC-62 5-A OR BC625-AM POWER OUTPUT.
(a) Operate the equipment is in paragraph 9b,
this section. Connect Cord CD-477 ( 5 feet long) to the
"PHANTOM ANT." socket on the meter panel of
Signal Generator I-96-A and to antenna socket 4 1 6 on
the rack. Connect the doc meter cord to the signal gen­
erator "D.C. METER" socket and transmitter socket 1 7 1 .
(b) I f Signal Generator I-96-A i s not being
used, employ Cord CD-477 terminated by a phantom
antenna and a 0-500 milliampere r-f millill1Ilmete'r.
(c) Tune the transmitter on the channel fre­
quencies listed in the table below. Antenna c'Ui'rent may
be read on the 0-500 milliampere r-f milliammeter.
(d) Record the milliammeter readings.
late the power output by applying the formula:
Calcu­
PR
W=106
Where W is the power output in watts, I is
the milliammeter reading and R is the phan­
tom-antenna resistance in ohms.
5-41
Section
V
A N 1 6-405 C I 6 2 4 - 2
P a ra g ra p h s 8 ( a )-9 a ( e )
TRANSMITTER POWE R OUTPUT
8.
Input to
Power Output (Watts)
Total Freque/lcy
Megacycles
Normal
100
1 10
120
1 30
140
1 50
1 56
7.7
8.9
9.7
9.9
8.8
8. 1
7.4
Minimum
6
6
6
6
6
6
6
3rd I. F.
2nd I. F.
1 st I. F.
Mixer
9.
a.
b. SELECTIVITY.-The following table gives selec­
tivity readings.
Test
Frequency
Nor­
mal
Input in
Microvolts
12 megacycles . 30 microvolts
Above below
x2
xlO
x 100
x l ,OOO
x 10,000
Bandwidth
Maximum
Minimum
100 megacycles
1 56 megacycles
100 milliwatts
500 milliwatts
SET
microvolts
microvolts
microvolts
microvolts
SCR-624 -A,
OR
TRANSMITTER TUNING USING TEST
EQUIPMENT IE- I9- ( * ) t
( 2 ) INITIAL PROCEDURE.
(See figure 2-1 .) '
120 90 kilocycles 1 5 0 kilocycles
195
2 30
280
335
440
385
565
Normal
Maximum
3.7 microvolts
7.7 microvolts
7.5 microvolts
15 microvolts
d. NOISE SUPPRESSOR.-Make a test to determine
whether there is an appreciable suppression of noise
by tuning the receiver to a relatively small signal and
then turning on some sort of noise generator such as the
ignition system of a motor or an electric drill. With
terminals 7 and l I on terminal board 10 shorted to­
gether for Radio Receiver BC-624-AM and with the
noise limiter switch off on Radio Receiver BC-624-C,
the noise limiter is not operating and considerable in­
terference should be encountered. When this short is
removed, the interference becomes relatively low.
N ote
If Signal Generator I-96-A, part of Test Equip­
ment IE-46- ( * ) is available, it may be used to
provide a source of pulse noise in the extreme
high frequency end of the band of the receiver.
e. INPUTS FOR STANDARD OUTPUT.-The fol­
lowing table gives input readings for standard output.
5 - 42
A L I GNMENT OF RADIO
SCR-624-B.
1 30,000
4,500
1 50
20
( 1 ) EQUIPMENT REQUI.RED.-The following
test equipment is required when tuning the transmitter.
[ Part of
(a) Field Strength Meter 1-95- ( * ) .
Test Equipment IE- I9- ( * ) .]
(b) Test Set 1- 1 39-A. [ Part of Test Equipment
IE- I9- ( * ) . ]
(c) Medium sized screw driver.
N ote
During the transmitter tuning procedure do
not remove Radio Set SCR-624-A or SCR624-B from Case CS-SO-A or CS-SO-C. The
additional capacitances introduced by replac­
ing the assembly in the case will tend to dis­
turb the tuning adjustments. The assembly
may be left in Chest CH-I 73-A or CH- 1 73-B
for tuning.
Receiver Input
Receiver
Output
grid
grid
grid
grid
Do not remove the transmitter or the receiver
from Rack FT-244-A for tuning.
c. RECEIVER A-F POWER.-The following table
gives receivt!r a-f power readings.
Test
Frequency
Control
Control
Control
Control
Input Voltage
IMPORTANT
OVER-ALL PERFORMANCE TESTS (RADIO
RECEIVER BC-624 -AM O R BC-624 -C) .
a. METHODS OF MEASUREMENT.-Methods of
measurement are identical with Radio Receiver BC­
'2.�A.
Measurement Point
(a) If the receiver and transmitter covers are
dosed, loosen the Dzus fasteners pinning them to the
outer cover. Raise the covers slightly and slide them
away from the tuning controls.
(b) Install crystals of the desired frequencies in
the crystal sockets. The crystal chosen for any trans­
mitter channel should have a rated fundamental fre­
quency one-eighteenth of the desired final output fre­
quency. ( Fundamental frequencies appear on the crystal
holders.)
(c) Connect Antenna AN-94-A, AN-94-B, or
AN-94-C to the antenna socket on Rack FT-244-A by
means of Cord CD-950-A or connect Antenna AN-ISS
by means of Cord CD- 1 333.
(d) Connect Control Box BC- 1 l 75-A or BC- 1 3 I2
to the IS-contact socket on Rack FT-244-A.
(e) Connect Rectifier Unit RA-62-B or RA-62-C
to Power Unit PE-75-D or to a 40- to 60-volt, 100- to
1 30-volt, or 200- to 260-volt source of a-c power if
available.
t For maintenance information
T. O. No. 08· 1 0 · 1 1 0 .
•
Refers to a n y issue.
on
Test
Equipment
IE·1 9·A
refer
to
AN 1 6- 405 CR624-2
(f) Connect Rectifier Unit RA-62-B or RA-62-C
to the 12-contact socket on Rack FT-244-A by Cord
CD-809-A.
(g) Plug the cord of Test Set 1-1 39-A into test­
meter socket 1 7 1 on the transmitter.
(h) Set the voltage selector switch on the recti­
fier to the proper input voltage .
(i) Place the "LOCAL-REMOTE" switch on the
control box in the "LOCAL" position.
0) Place the "ON-OFF" switch on the rectifier
unit in the "ON" position.
(k) Select any channel using the "A-B-C-D­
CHANNEL" switch on the control box. Selecting a
channel will cause the frequency shifter mechanism to
operate and shift the equipment to the channel selected.
Note
If the transmitter fails to operate when a
channel is selected on the radio control box,
select another channel. Then select the channel
for the desired control.
(l) Release the frequency shifter mechanism by
pressing channel release button 426 or by pressing the
armature of motor 406 onc�.
(m ) Loosen the four transmitter tuning control
lock nuts slightly by turning them counterclockwise.
(n ) Tighten the four lock nuts j ust enough to
exert a slight pressure on the cam pile-up.
Note
Avoid tuning to an · undesired harmonic by
making certain that all four R!:ni�g controls,
when adjusted, indicate approximately 1ile
desired output frequency on the calibratio h
plate.
( 3 ) TUl�ING OF FIRST CHANNEL.
(a) Select any frequency channel by meiln� . of
the "A-B-C-D-CHANNEL" switch on the COtltt@I l;o x
and completely loosen all tuning control lock nuts.
N ote
Whenever a channel is selected the switching
mechanism will select and release channels in
the sequence "A," "B," "C," "D," until the
desired channel is selected.
(b) Allow about one minute for the tubes to
warm up. This can be observed by placing the trans­
mitter "METER SWITCH" in position 3 and noting
a rise of current in Test -Set 1 - 1 39.
(c) Place the "SEND-REC-SEND" switch on
the control box in the "SEND" position on Control Box
BC- 1 3 1 2 or press the "PRESS-TO-TALK" button on
Control Box BC- 1 l 75-A.
(d) Place the transmitter "METER SWITCH"
in position 1 and adjust the oscillator plate tuning con­
trol ( first tuning control at left as shown in fig. 2 - 1 )
for maximum reading o n Test Set 1-1 39�A.
Secti o n
V
P a ra g ra p h 9a (II-9a5 (g)
( e) Repeat, using "METER SWITCH" positions
"2': and "3" respectively and the second and third con­
trols respectively and in consecutive order.
(f) With the "METER SWITCH" in position
"3," tune the fourth tuning control for a dip on the
test set. Record the meter reading.
(4) TUNING OF REMAINING CHANNELS.
IMPO RTA NT
Before depressing the next channel push but­
ton, hold the channel controls with the finger
and tighten the lock nuts j ust enough to exert
a slight pressure on the cam pile-up. While
doing this make certain that the test set read­
ing does not change.
(a) Select the channel on the control bo-x which
follows the channel j ust tuned.
(b) Loosen all tuning control lock nuts.
(c) Follow , the same tuning plltKedure outlined
in paragraph 9a( 3 ) , this section.
(d) Tune the remaining channels in like mannero
(e) Do not make any further adjustments of the
antenna-coupling control.
(f) Record the meter reading obtained on all
four channels with the "METER SWITCH" in position
"3." Select the channel which had the highest meter
reading with the "METER SWITCH" in position "3."
If the meter reading is less than 0.60 or greater than
0.65, change the antenna coupling control as described
in paragraphs ( 5 ) and ( 6) below.
( 5 ) ADJUSTMENT OF THE LOCKING TYPE
ANTENNA COUPLING CONTROLS.
(See figure 4-5.)
(a) If the reading is less than 0.6, increase the
coupling by loosening the antenna coupling control
thumbscrew (see fig. 4-5) and pushing it slightly
toward the tuning controls.
(b) Tighten the thumbscrew and adjust the
fourth tuning control for a minimum reading on the
test set.
(c) If the reading is more than 0.65, decrease
the coupling by loosening the antenna coupling control
thumbscrew and moving it slightly away from the tun­
ing controls.
(d) Tighten the thumbscrew and adjust the
fourth tuning control for a minimum reading on the
test set.
(e) Repeat this procedure, alternately adjusting
thumbscrew and the fourth tuning control, until the '
correct meter reading is obtained.
(f) Do not consider a reading of more than 0.65
acceptable since such an adjustment will result in early
tube failure.
(g) Record the meter reading finally obtained
for later reference.
5 - 43
Secti o n V
Paragra p h 9a(6)-9aI9)(j)
AN 1 6- 40S C R624-2
(6) ADJUSTMENT OF THE NON-LOCKING
TYPE ANTENNA COUPLING CON­
TROL.
(See figure 4-6.)
The non-locking type antenna coupling control is a
feature of the later models of Radio Transmitter BC62 5-A or BC-62 5 -AM. Adj ust the control as follows:
(a) If the reading on Test Set 1- 1 39-A is l�ss
than 0.6, increase the coupling by rotating the contr�
knob counterclockwise toward "MAX."
I
(b) With the "METER SWITCH" in position
"3" and with the channel selector engaged, rotate tun­
ing control 4 slightly against the positioning detent.
Repeat this check on each channel. If the transmitter
is properly tuned, rotation in either direction will cause
an increase in the meter reading.
WARN I NG
Do not use excessive pressure against the po­
sitioning detent.
N ote
In general, meter readings greater than
three-quarters full-scale with the "METER
SWITCH" in any one of its positions indi­
cates a defect in the equipment or improper
adjustment. An exception to this generali­
zation occurs when the "METER SWITCH" is
in position "5," in which some of the vacuum
tubes used may cause a full-scale or even off­
scale reading, which is desirable. On some
equipments position "4" of the "METER
SWITCH" is not used due to the elimination
of the r-f indicator diode. Position "6" is an
off or open switch position.
CAUTION
Do not attempt to tighten the control knob
as the knob serves only as an indicator of the
relative position of the coupling coil. Do not
tum the adjusting knob beyond "MAX" or
"MIN" as damage to the equipment will re­
sult.
(b) Adjust the fourth tuning control for a mini­
mum reading on the test set.
( c) . If the reading is more than 0.65, decrease
the coupling by turning the control knob clockwise
toward "MIN."
(d) Adjust the fourth tuning control for a mini­
mum reading on the test set.
( e) Repeat this procedure alternately adjusting
the control knob and the fOourth control until a reading
of approximately 0.63 is obtained on the test set.
(f) Record the meter reading for later reference.
( 7 ) FINAL TIJNING.
(a) Retune the three remaining channels follow­
ing the sequence in which the channels were originally
tuned. (Refer to par. 9a( 3 ) , this section, for tuning
procedure.) Do not disturb the setting of the antenna
coupling control. A reading of 0.50 on some channels
is satisfactory.
(b) When all the channels are tuned, press the
channel release button. Carefully tighten the tuning­
control lock nuts with the fingers. If necessary, tighten
with a tool but avoid exerting excessive force.
IMPORTANT
These lock nuts must be properly tightened or
the tuning adjustments will not hold and the
entire tuning procedure will have to be re­
peated.
( c) Make sure that · all adjustments are securely
locked by switching to each ch annel several times, check­
ing the meter readings on "METER SWITCH" posi­
tion "3" against those recorded while making the
tuning adj ustments.
( 8 ) TUNING CHECKS.
(a) When the tuning-control lock nuts have
been tightened and the transmitter "METER SWITCH"
set in positiOon "5," the meter reading for all .channels
will be full scale or more. Any reading greater than
half-scale is satisfactory.
5 -44
(c) After tuning has been completed, tune in
the unmodulated carrier on Field Strength Meter 1-9 5 ( * ) . Whistle a sustained note into t h e microphone.
An increase in the reading on the. milliammeter of the
field strength meter should occur, indicating modulatiOon
of the carrier.
( 9 ) TIJNING OF A SINGLE CHANNEL OUT
OF ADJUSTMENT.-If one channel is known to be
out of adjustment, it may be tuned without disturbing
the other channels as follows:
(a) Using the "A-B-C-D-CHANNEL" switch
on the control box, select the channel Oon the cOontrol box
preceding the desired channel in the sequence "A," "B,"
"C," "D." In other words, if returning channel "A,"
select channel "D," if retuning channel "B," select
channel "A," etc.
(b) Press the channel-release push button on the
rack.
( c) Loosen all transmitter . tuning-control lock
nuts, keeping slight pressure on the cam pile-up.
(d) Press the selector push button corresponding
to the desired channel and completely loosen all tuning
control lock nuts.
( e) Tune the desired channel. ( Refer to par. 9a,
this section. )
(f) Press the channel-release push button.
(g) Tighten all transmitter tuning control lock
nuts with the fingers. If a tool is used, do not tighten
lock nuts excessively.
( h) Press the channel-release push button to re­
select the channel just tuned.
(i) Check the meter reading for the highest
loaded channel. If the reading is approximately 0.63,
•
Refers to a n y issue.
AN 1 6-40SCR624-2
no adjustment of the antenna coupling is necessary.
If it is less than 0.60 or more than 0.65 readjust the
coupling on this channel in accordance with the in­
structions in paragraph 9b, this section.
IMPORTANT
If th� antenna-coupling control is readjusted,
re-tune the third and fourth tuning controls
for the proper meter reading on "METER
SWITCH" position "3" on all channels.
( lO) "GAIN" CONTROL ADJUSTMENT.
With any channel switched on and all channels tuned,
adjust the "GAIN" control (see fig. 4-1 ) with a screw
driver for normal voice level under conditions of nor­
mal operation. A setting of between 30 degrees and
60 degrees from the maximum clockwise position is
usually satisfactory. Once m!ade, this adjustment is
good for all channels. (The "GAIN" control has
been replaced by a fixed attenuator network in later
models of the radio transmitter. )
IMPORTANT
Never shut off the equipment with the shifter
slides disengaged as this will result in failure
to turn on the transmitter and receiver if a
channel is selected on the control box.
b. TRANSMITTER TUNING USING TEST
EQUIPMENT IE-36.
N ote
Refer to Handbook of Maintenance Instruc­
tions for Test Equipment IE-36 for mainte­
nance instructions. ·
( 1 ) EQUIPMENT REQUIRED.-Test Equipment
IE-36, Test Set I- 1 39-A and a microphone, either car­
bon (Microphone T- 1 7 ) or magnetic (Microphone
T-44) are needed for transmitter tuning.
( 2 ) INITIAL PROCEDURE.
(a) Radio Transmitter BC-625-A or BC-62 5-AM
must be inside Case CS-So-A or Case CS-SO-C when
being tuned and Radio Receiver BC-624-A, BC-624AM or BC-624-C must be connected. If the trans­
mitter is tuned while removed from the case, the
additional capacitances introduced by replacing the
transmitter in the case will upset the tuning adjust­
ments.
(b) If the receiver and transmitter covers are
closed, loosen the Dzus fasteners pinning them to the
center cover. Raise the covers slightly and slide them
away from the tuning controls.
(c) Select a crystal having a rated fundamental
frequency one-eighteenth of the desired final output
frequency. ( Fundamental frequencies appear on the
crystal holders.)
(d) Connect Antenna AN-94-A, AN-94-B, or
AN-94-C to Socket SO- I 5 3 or Rack FT-244-A by means
of Cord CD-950-A or connect Antenna AN-ISS by
means of Cord CD- 1 333.
Sectio n V
Para g ra p h 9a(9)(j)-9b(4)(a)
(e) Connect Control Unit BC- I303 to Rack FT244-A by inserting the I S-contact plug on the bottom
of the control unit in the I S-contact socket of the
rack. Insert Test Set I- 1 39-A in the transmitter meter
socket.
( 3 ) TUNING CHANNEL A
(a) Turn the control unit "OFF A-B-C-D"
switch to "D."
(b) Press channel release push button 426.
(c) Loosen the transmitter control lock nuts 1 ,
2 , 3 and 4 until they exert only a light pressure on
the cam.
(d) Turn the "OFF A-B-C-D" switch on the
control unit to "A."
(e) Loosen the tuning control lock nuts com­
pletely.
(f) Turn the transmitter "METER SWITCH"
to position "3" and check Test Set I- 1 39-A for current
reading from .4 to .65 milliamperes.
(g) Throw the "T-R-REM" switch on the con­
trol unit to the "T" position.
(b) Avoid tuning to an undesired harmonic by
making certain that all four tuning controls, 1 , 2, 3
and 4, when adjusted, indicate approximately the de­
sired output frequency on the calibration plate. Check
to see if the proper crystals are installed.
(i) Turn transmitter "METER SWITCH" to
position " I ." Adjust the transmitter tuning control 1
for a maximum reading on Test Set I-1 39-A turning
the black plate under the lock nut either to the left
or right.
(i) Turn transmitter "METER SWITCH" to
position "2" and adjust tuning control 2 for a maxi­
mum meter reading.
(k) Turn transmitter "METER SWITCH" to
position "3" and adjust tuning control 3 for maximum
meter reading.
(l) Leave transmitter "METER SWITCH" at
position "3" and adjust control 4 for a "MINIMUM"
meter reading.
"
."
N ote
After Antenna AN-94-A, AN-94-B, AN-94-C,
or AN-I SS has been tuned to the radio trans­
mitter by means of the transmitter tuning con­
trol 4 (see fig. 4-5) by use of "METER
SWITCH" position "3," do not retune to
Phantom Antenna A-29 because the capaci­
tance and resistance differ.
(m) If the meter readings in steps (j) and (k)
are more than "65," adjust the antenna coupling con­
trol as directed in paragraph 9a( 5 ) and (6), this sec­
tion . Reset controls 1, 2, 3 and 4.
(4) ADJUSTMENT OF REMAINING
CHANNELS.
(a) To tune channel "B," turn the "OFF
A-B-C-D" switch on Control Unit BC- 1 303 to "B" and
5 - 45
Section V
P a ra g ra p h 9(bl-9b(9(0 1
AN 1 6-40S C R 6 2 4 - 2
follow the same tuning procedure outlined for chan­
nel "A" in 9a ( 3 ) above. However, do not change the
antenna coupling adj ustment unless the meter reading
is more than "65." Tune channels "c" and "D" in like
manner.
(b) Press the channel release control button
426 and tighten lock nuts on tuni.ng adjustment 1 , 2 ,
3 and 4.
( 5 ) METER CHECK.
(a) When the tuning control lock nuts are tight
and the transmitter "METER SWITCH" is in position
"5" the meter reading for all channels should nor­
mally be full scale (0. 1 ) or more. Any reading greater
than half scale (0.5 or more) is satisfactory. If this
condition is not achieved for any channel, readjust
tuning control 3 for a maximum reading ("METER
SWITCH" ( 1 65) position " 5 " ) , returning that par­
ticular channel in accordance with the procedure in
paragraph 9a(9) above.
(b) When the tuning control lock nuts are tight,
there is a positioning detent which makes it possible to
turn the tuning controls slightly, in either direction
against' spring pressure. In some cases a large amo�t
of torque is necessary to rotate the controls. Tumng
controls 1 , 2, and 3 can be checked by rotating them
in both directions against the positioning detent, and
by noting that n�aximum meter reading occurs in the
resting position of the control. If the meter reading
is not a maximum in the resting position retune that
particular control in accordance with paragraph 9a,
this section.
CAUTION
Do not exert excessive pressure against the
dent.
( 6) FINAL MODULATION CHECK.
Note
Do not retune during this check.
(a) Insta ll Phantom Antenna A-29 in Antenna
Socket SO-l53.
(b) Plug in the microphone. (Refer to par.
9a( 6), this section.
(c) Whistle a sustained note into the micro­
phone and note the action of the pilot lamp on Phan­
tom Antenna A-29. If the carrier wave is being modu­
lated p roperly, there will be an increase in brilliance
in the lamp on the phantom antenna.
(d) Replace Antenna AN-94-A, AN-94-B, AN94 - C or AN- ISS in antenna Socket SO- l 5 3 .
Note
Never shut off the radio set with the shifter
slides disengaged, as this will result in failure
to tum on ' the transmitter and receiver if
one particular channel is selected.
( 7 ) PROCEDURE FOR TUNING ONE CHAN­
NEL ONLY.-If it is known that one channel is out
of adjustment it may be tuned without disturbing the
other channels. (See par. 9a ( 9 ) , above. ) The fol­
lowing is a brief summary of the procedure.
5 - 46
(a) Tum the "O FF A-B-C-D" switch to the
channel preceding the desired channel in the sequence
"A," "B," "C, '" "D," et cetera .
( b) Press the channel-release push button 426
on Rack FT-244-A.
(c) Loosen all transmitter tuning-control lock
nuts.
(d) Tum the "OFF A-B-C-D" switch to the
desired channel.
(e) Tune the desired channel. Refer to par.
9a ( 3) above. )
(f) Press the channel-release push button 426.
(g) Tighten all transmitter tuning-control lock
nuts 1, 2, 3, 4.
(h) Press channel-release push button 426.
(;) Check the meter reading on the lowest fre­
quency channel. If this reading is approximately 0.63,
do not adjust the antenna coupling control. If it is
less than 0.60 or more than 0.65, adjust the coupling
on this channel in accordance with the inStructions in
paragraph 9a ( 3 ) above.
( 8 ) ADJUSTMENT OF THE TRANSMITTER
"GAIN" CONTRO L.-With any channel switched on,
all channels tuned, and the airplane engines running,
adjust the "GAIN" control 1 2 5 for normal voice level
under conditions of normal operation. A setting of
from 30 degrees to 60 degrees ' from the maximum ,
clockwise position is usually satisfactory.
Note
In all cases, the point of proper adjustment of
the "GAIN" control 1 2 5 is that which gives
maximum volume without excessive distortion
in a second receiver. This adjustment once
made, is good for all channels. In some models
of the transmitter, this gain control has been
locked with glyptal at the point of proper
operation; and in later models of the trans­
mitter the "GAIN" control has been replaced
by a fixed attenuator network.
(9) SIGNIFICANCE OF METER READINGS.
(a) In general, meter readings on Test Set 11 39-A greater than 0.65 with the transmitter "METER
SWITCH" 1 65 in position " 1 ," "2," "3" indicates a
defect in the equipment or improper adjustment.
Position
2
3
5
6
Current
First Harmonic
Amplifier Plate
Second Harmonic
Amplifier Plate
Power Amplifier Plate
(average for channels A, D, C, D)
Power Amplifier Grid
Normal
Meter
Reading
Trouble
.4
Greater than
.65
.5
Greater than
.65
.63
Greater than
.65
Full
scale
Off
Less than
.5
AN 1 6-405CR624-2
(b) In some sets r·f diode current is measured
with the "METER SWITCH" ( 1 65 ) in position "4."
This switch position is seldom used. The reading ob­
tained is purely relative, without quantitative signifi.
cance, and is equivalent to a neon·bulb indication of
r·£' voltage across the final amplifier tank inductor.
In those transmitters in which the diode indicator has
been deleted, position "4" gives no reading.
( �) The reading of Test Set I·1 39·A obtained
with the "METER SWITCH" in position "5" is an·
other variable quantity. Transmitting tube data sheets
describe grid "drive" or grid current as "approximate,
subject to wide variations depending on the impedance
of the load circuit." It is desirable that this current be
as large as possible ( even off·scale) . The real test of
satisfactory adjustment is whether or not "upward
modulation" of the carrier results.
(d) It is reasonable to assume that half·scale or
higher meter readings, with the "METER SWITCH"
in position "5," are satisfactory although there are
exceptions to this rule.
( e) Note that there is an idle or standing plate
current resulting in a meter reading of approximately
0.4 wheri the "METER SWITCH" 1 65 is in position
"3" and Radio Set SCR·624·A or SCR·624·B is in the
receive condition. This is normal and correct and in·
dicates the existence of a load on the modulator at all
times. If this current is abnormally high, an open or
short circuit is indicated in the minus 1 50 volt bias
supply from Dynamotor Unit PE·94·A.
(f) When the "METER SWITCH" is in posi.
tion "4" note that there is a small omission current
in the r·f diode in the "standby" condition, unless the
r·f diode indicator: tube has been deleted, in which case
there will be no reading.
(g) Position "6" of "METER SWITCH" is an
"OFF" or open switch position. ( Position "4" will also
be an open switch position on sets in which the r·f
indicator diode has been omitted. )
�.
RECEIVER I·F AMPLIFIER TRANSFORM ER
ALIGNMENT .
( 1 ) Do not attempt i·f alignment before checking
tubes and the receiver sensitivity on all channels, with
all channels properly tuned. If the sensitivity on any
channel is below the values given in paragraph 9 b ( 9 ) ,
proceed with the alignment.
( 2 ) If a Ferris 18C signal generator is not avail·
able for perfomlance tests, compare the sensitivity of
the receiver under test with a receiver known to be
in good condition by using Signal Generator I·96·A or
I-1 30·A. Note whether or not the minimum attenuator
setting for audible receiver output is considerably higher
for the receiver under test than for the good receiver.
Proceed only if this test indicates that i-f alignment is
necessary.
Section V
Paragraph 9&(9)(&)-9,(3)(e'
( 3 ) Any signal generator capable of producing
an output of approximately one volt at a frequency
of exactly 12 megacycles, and having a terminated
transmission line output, is suitable for use in receiver
i-f alignment. Modulate the r-f voltage
. approximately
30 percent at 400 to 1000 cycles.
Note
These instructions are written on the assump­
tion that Signal Generator I·96-A (part of
Test Equipment IE- 12-A) is employed. How­
ever, if another type of generator is being
used, make adjustments which are equivalent
to those specified here for Signal Generator
I-96-A.
(a) Renio�e the assembly comprising the trans­
mitter, receiver and rack from Case CS-8o-A or Case
CS-80-C.
(b) Set the Signal Generator I-96-A up �ithin
5 feet of the radio receiver to be tuned and plug one
end of the signal generator doc meter cord into the
receiver test-milliammeter socket 288 located on the
receiver control panel (see fig. 2-1) and plug the
other end into the "D.C. METER" socket located on
the signal generator meter panel . Plug the i-f test
cord into the signal generator "I.F. OUTPUT" socket
marked "HIGH." Connect the "OUTPUT" terminal
of the i-f test cord to the mixer tube grid lead lo­
cated on the right side of the receiver and connect the
"GND" terminal to the variable capacitor frame as
shown 011 fig. 4- 1 1 . Keep these leads as short as pos­
sible, never longer than 1 % inches. Otherwise the i-f
amplifier may feed back and oscillate or be difficult to
tune properly.
CAUTION
Do not allow the output lead to touch plate
terminal No. 7, of the mixer socket, as this
may burn out the resistor in the cable terminal
box.
( c) Connect an output-PO'wer meter or an a-c
voltmeter (if available) across the audio output of the
connector panel terminals. Connect a low-impedance
head set across the same terminals to' give the operator
.
an aural indicatiO'n.
(,d) Adjust the load presented by the O'utput­
PO'wermeter O'r the a-c vo.ttmeter to' 4000 ohms if the
yellow wire gO'ing to the receiver audio-output trans­
former 296 is connected to terminal No. 7. Adjust the
load to 300 ohms if this wire is cO'nnected to terminal
NO'. 6 on Radio Receiver BC-624·A or BC-624.AM.
(On Radio Receiver BC·624·C the 300·ohm tap is ter·
minal 4 and the 4000-O'hm tap is terminal 5 on trans·
former 200.) This arrangement provides a more satis·
factory tuning indication than can be obtained by using
the signal generatO'r " D.C. METER:'
(e) If no O'utput meter is available, use the sig·
nal generator . "D.C. METER" as a tuning indicator.
Adjust the transfO'rmers, as outlined below, fO'r peak
5 -47
Section V
Para g ra p h 9c3(1)-9c6
AN 1 6-405 CR624-2
output in the head set with the signal generator attenu­
ator adjusted for comfortable headset volume; then
readjust, if necessary, as alignment progresses, to main�
tain that volume.
(f) If a 1 10 to 1 1 5-volt 50-60 cycle power sup­
ply source is available, plug the a-c line cord into the
power source and into the a-c socket on the upper
right side of the "A.e. POWER SUPPLY" panel of
Signal Generator I-96-A. Throw the signal generator
"A.e. ON·OFF" switch to "ON," the "A.C. ON-OFF"
switch to "OFF," and "A.C.-D.e." switch to "A.e.,"
and the "I.F.-�.F." switch to "I. F."
(g) I f no external a-c power source is available,
throw the "A.e. ON-OFF" switch to "OFF," the "D.C.
ON-OFF" switch to "ON," the "A.e.-D.e." switch to
"D.e.," and the "I.F.-R.F." switch to "I.F."
(h) It is not necessary to use receiver crystals
for i-f alignment. Set up the transmitter, receiver and
rack for operation by use of Radio Control Box BC1 1 75-A or BC- 1 3 1 2 (see figs. )-6 and )-7) . Press any
channel-selector push button "A," "B," "C," or "D"
on the radio control box. Place the control box "SEND­
REC" switch in "SEND" position. Allow about one
minute for the receiver vacuum tubes to warm up. Set
the receiver "AUDIO" and "RELAY" or "SQUELCH"
controls in their maximum clockwise rotation positions.
CAUTION
In the clockwise rotation of the "RELAY" or
"SQUELCH" control on Radio Receiver BC624-C be careful not to operate the noise lim­
iter switch (the snap of the switch can be
heard if the control is rotated too far clock­
wise) .
(;) I f an output meter or a-c voltmeter i s used,
adjust the signal generator "ATIENUATOR" to the
position which results in an audio output of approxi­
mately 50 milliwatts (or 1 5 volts rms across 4000ohm load, or 4 volts rms across 300-ohms load) . If
another type of generator is being used, set the out­
put frequency at exactly 12 megacycles and adjust the
attenuator for an output meter reading of 50 milli­
watts, just as for S ignal Generator I-96-A. As tuning
progresses, it may be necessary to readjust the "AT­
TENUATOR" continually or even to transfer the i-f
test cord to the "LOW" output socket to retain a re­
ceiver audio output of approximately 50 milliwatts. In
some cases, it may be necessary to readjust the receiver
"AUDIO" control if considerably more than . 50 mi1li­
watts output is obtained with the "ATIENUATOR"
set at "MIN."
0) I f the signal generator "D.e. METER" is
used as a tuning indicator, place the meter switch in
the "TRANS-REe. TUNING" position anel initially
set the "ATTENUATOR" at the point which results
in a slight dip in the meter reading. As tuning prog­
resses, reduce the signal generator output by means ot
the "ATIENUATOR" to retain a meter reading of
approximately the same value as that initially obtained,
5-48
transferring the i-f test cord to the "LOW" output
socket, if necessary.
(k) Using the alignment tool or a small screw
driver, adjust the iron core tuning screws on top of
transformer 294 for maximum audio output (or mini­
mum "D.C. METER" reading) . Repeat for transformer
293, 292 and 291, in that order, reducing the signal
generator output, if necessary as explained in paragraph
9c, this section.
(I) Repeat the procedure given in paragraph 9c..
this section, to see if any further improvement in i-f
alignment is possible.
(m ) Press the "OFF" button of the radio con­
trol box, remove the leads from the . mixer tube and
the variable capacitor frame and replace the rack, re­
ceiver and transmitter in Case CS-SO-A or C5-so-C.
Howev�r, if no output-power meter is available and
if the i-f stages were out of the adjustment to such
an extent that it was impossible to obtain a "D.C.
METER" indication, follow the method outlined below.
1 . Remove the transmitter from the rack.
( See paragraph 4a, this section. )
CAUTION
To prevent damage to equipment, release fre­
quency shifter mechanism before attempting
to remove transmitter or receiver from rack.
2. Using a short length of wire, ground ter­
minal 4 of socket 41S-1 (see fig. 4-20) to the rack
chassis to permit channel selection by ' means of the
radio control box. Insert a wedge between the arma­
ture and the backstop of the locking relay 4,1 1 - 1 1000ted
on the left side of the rack. (This must be done to.
keep antenna relay 412 in the energized position so
that plate and screen voltage is applred to the receiver
r-f and i-f circuits. )
3. Plug the i-f test cord into the signal gen­
erator "I.F. OUTPUT" socket marked "HIGH" and
connect ' the "OUTPUT" terminal of the i-f test cord
to the grid of the third i-f tube JAN-12 5G7. (See fig.
4-1 1 .) Connect the i-f test cord "GND" terminal to
the nearest point on the receiver chassis.
4. Set the control-box "T.R.-REM" switch at
"R" and press any channel-selector push button. Allow
about one minute for the receiver vacuum tubes to
warm up. Set the receiver "AUDIO" and "RELAY"
controls in their maximum clockwise rotation position.
) . Place the signal generator meter switch in
"TRANS-REC. TUNING" position and initially- set
the "ATIENUATOR" at the point which results in a
slight dip in the "D.e. METER'" reading. As tuning
progresses, reduce the signal generator output by means
of the "ATIENUATOR," as explained in paragraph
9b, this section.
6. Using the alignment tool or a small screw
driver, adjust the iron core tuning screws of transformer
294 (see fig. 4-10) for minimum "D.e. METER"
reading.
AN 1 6-40SCI624-2
7. Gonnect the "QUTPUT" terminal of the
i- f t�t cord to the grid of the s econd i-f, first i-f and
mixer tubes resp e ctively (see fig. 4-1 1 ) and adjust the
iron core tuning screws of transformers 293, 292, and
291 respectively (see fig. 4-1 0) for minimum "D.C.
METER" reading.
8. With the "QUTPUT" termi nal of the i-f
test cord connected to the grid of the mixer tube and
the "GND" tenninal connected to the variable capacitor
frame, readjust all the iron core tuning screws to see
if better i-f alignment can be obtained.
d. RECEIVER TUNING USING TEST EQUIP­
MENT IE- 19 ( * ) .
( 1 ) EQUIPMENT REQUIRED.
(a) Test Equipment IE- 19- ( * ) .
(b) Headset.
(c) Medium sized screw driver.
( 2 ) INITIAL PRQCEDURE. - If the receiver
cover is shut, loosen the Dzus fasteners pinning it to
the center cover, lift the receiver cover slighdy and
slide it away from the control panel .
( 3 ) CRYSTAL SELECTIQN.
(a) A receive r crystal is identified by the funda­
mental frequency in kilocycles which appears on the
crystal holder.
(b) Finding the correct receiver crystal for a
particular receiver channel is therefore the same as fi nd ­
ing the correct fundamental frequency (kilocycles) of
the crystal to be used.
(c) The fundamental crystal frequency may be
detennined from the e xpression :
f = fr - 12
---
H
x 1000
Where fr is the frequency in megacycles to
which the receiver is to be tuned and H is the
receiver crystal harmonic used (see the follow­
ing table). The receiver crystal harmonic (H)
used depends only on the frequency (fr) to
be tuned in, and is given in the following table.
frequetlcy (f r)
100- 108
108- 1 16
1 16- 124
124- 1 32
1 32- 140
140- 148
148- 1 56
1 56
Megacycles
Megacycles
Megacycles
MegacyCles
Megacycles
Megacycles
Megacycles
Megacycles
Receiver Crystal
Harmonic (H)
11
12
13
14
15
16
17
18
(4) ADJUSTMENT QF SIGNAL GENERATQR
I-1 30-A. ( USING CRYSTAL. )
(a) Insert a transmitter crystal having a funda­
me nta l freq u e ncy o ne-eightee n th of the receiver fre... Refers to any issue.
Section V
Paragra p h 9c7.-9d(6)(b)
quency to be tuned in the "CRYSTAL" socket of Signal
Generator I- 1 30-A.
(b) Connect Cord CD-477 to the signal genera­
tor "R.F. QUTPUT', socket and to the antenna socket
Socket SQ- 1 5 3 located on Rack FT-244-A. Connect
Test Set. I-1 39-A to the signal generator "METER"
socket_
(c) Plug the cable of Battery Box BX-33-A
into the signal generator four-pin socket located to the
l eft of the "METER" socket. Thow the signal gettera- ,
tor "POWER ON-QFF" switch to "QN."
(d) Set the signal generator "M.Q .-CRYS­
TAL" switch at "CRYSTAL."
(e) Place the "QUTPUT CQNTRQL" on
"MAX." ( extreme ' clockwise position ) and place the
"QUTPUT STEPS" control on step 5.
(f) After allowing about one minute for the
tubes to warm up, adjust the "CRYSTAL TUNING"
control to the frequency to be tuned,. If this adj ust­
ment is correct, a small dip will be observed in the
Test Set I-139-A.
(g) Adj ust the "MEGACYCLES" dial control
on the signal generator for an additional dip ( approxi.
mately at the same dial setting as the receiver channel
frequency being tuned ) .
(h) Starting from the extreme clockwise posi­
tion, slowly turn the channel "A" oscil lator plate-coil
tuning screw counterclockwise so that about three to
five threads of the screw protrude from the coil-mount­
ing insert. The higher the crystal frequency the fur­
ther the plate-coil screw must be backed out of the coil­
mounting insert to obtain the necessa ry inductance to
permit the oscillator to start. When the oscillator
starts, a signal should be heard.
(i) If there is no audible signal, simultaneously
adjust the receiver r-f and oscillator tuning controls
slighdy, and if necessary, turn the channel "A" oscil­
lator plate-coil tuning screw still further counterclock­
wise until the signal is heard.
( 5 ) ADJUSTMENT QF SIGNAL GENERATQR
I-1 30-A (USING MASTER QSCILLATQR) .-Use the
same procedure for employing the signal generator
master oscillator as the procedure for employing the
crystal oscillator except for . the changes listed below:
(a) Do not touch the "CRYSTAL TUNING"
co n trol .
(b) Set the "M .Q.-CRYSTAL" switch at
"M.Q."
(c) Tune the signal generator by means of the
"MEGACYCLES" dial control only.
(d) Allow about one minute for the tubes to
wann up.
(6) TUNING OF CHANNEL "A." (USING
CRYSTAL IN SIGNAL GENERATQR) .
(a) Install the proper crystal in the socket for
receiver channel "A."
(b) Select channel "D" by means of the "A-B­
CD-CHANNEL" switch on the control box.
5 -49
Section V
Paragra p h 9d(6)(cl-9d(7)(jJ
AN 1 6-40SCR624-2
Note
If the receiver fails to operate when a channel
is selected on the control box, select another
channel, then again press the push button for
the desired channel. Reception should now be
possible.
(c) Press the channel-release push button 426
located on the rack.
(d) Loosen the two receiver tuning-control lock
nuts by turning them counterclockwise. Tighten the
two lock nuts just enough to exert a slight pressure on
the cam pile-up. Otherwise vibration may change the
position of the cam, introducing considerable set-up
error.
(e) Select channel "A" on the control box and
completely loosen all tuning-control lock nuts. After
allowing about one minute for the receiver vacuum
tubes to warm up, place the "SEND-REC.-SEND"
switch on Control Box BC- 1 3 1 2 in the "REC." position.
Control Box BC- 1 1 75-A is in the receive position when
the "PRESS-TO-TALK" button is not depressed.
(f) Turn the receiver r-f and oscillator tuning
controls to the desired frequency on the calibration
plate.
(g) Connect a suitable headset across the audio
output terminals on the j ack box. Rotate the receiver
"AUDIO" and "RELAY" or "SQUELCH" controls to
their maximum clockwise rotation positions, being care­
ful on Radio Receiver BC-624-C not to rotate the "RE­
LAY" or "SQUELCH" control far enough clockwise
to operate the noise limiter switch.
(b) When the signal is heard, rotate the oscil­
lator plate-coil tuning screw clockwise until the signal
suddenly ceases, then rotate the screw counterclock­
wise to a position at least three-quarters of a turn past
the point at which the signal again becom,es audible
(i.e., the position at which the oscillator starts) . The
additional three-quarters of a turn is required for a
stable adjustment of the crystal oscillator. If the output
is decreased appreciably by this extra rotation, continue
turning the screw counterclockwise until a second peak
is reached. If this second p eak signal is greater than the
signal heard at the three.quarters counterclockwise turn,
leave the tuning screw in this position. If the signal is
less, return the tuning screw to the three-quarters
position. Check this adjustment after completing steps
(i) and (j) below.
(i) Turn the signal generator "OUTPUT CON·
TROL" to "MIN." Place the "OUTPUT STEPS" con­
trol in position I or 2 . Turn the "OUTPUT CON­
TROL" clockwise until the signal is just audible.
(j) Adjust the receiver tuning control and the
signal generator "CRYSTAL TUNING" control for
maximum audio output. Rotate the "OUTPUT CON·
TROL" counterclockwise, if necessary, to keep the
peaked output at low level in the headset. This may
require repeated readjustments.
5-50
(7) TUNING OF CHANNEL "A" USING
GENERATOR MASTER OSCILLATOR.
(a) Select channel "D" by means of the "A·B·
C-D-CHANNEL" switch on the control box.
N ote
If channel "A" has already been selected,
channels "B" and "C" will be switched on and
off before channel "D" is reached.
(b) Press channel release push button 426.
(c) Loosen the two receiver tuning. control lock
nuts by turning them counterclockwise. Tighten the
locknuts j ust enough to exert a slight pressure on the
cam pile-up.
(d) Select channel "A" on control box and com·
pletely loosen all tuning control lock nuts. After allow·
ing about one minute for the receiver vacuum tubes to
warm up, place Control Box BC· 1 2 1 3 "SEND·REC·
SEND" switch in the "REC" position. Control Box
BC- 1 1 75-A is in the receive position when the " PRESS.
TO·TALK" button is not depressed.
( e) Turn the receiver r·f and oscillator tuning
controls to the desired frequency on the callibration
plate.
(f) Using the alignment tool or a small screw
driver, turn the crystal oscillator plate-coil tuning screw
for channel "A" to the position at which about 3 to 5
threads protrude from the coil-mounting insert. The
higher the crystal frequency, the further the plate coil
screw must be backed out of the coil.mounting insert,
to obtain the necessary inductance to permit the oscil·
.
lator to start.
(g) With a head
audio output, place the
STEPS" control on step
CONTROL" at "MAX."
set connected to the proper
signal generator "OUTPUT
"5" and set the "OUTPUT
( extreme clockwise position) .
(b) Set the signal generator "MEGACYCLES"
dial control at the frequency being tuned and then
adjust the receiver tuning controls until the modulated
signal is heard in the headphones. This may require
several readjustments.
(i) Turn the oscillator plate·coil tuning screw
for channel '.'A" clockwise until the modulated signal
suddenly ceases.
(j) Turn the crystal. oscillator plate-coil tuning
screw counterclockwise until the signal is again heard.
An additional three-quarters of a full turn in a counter­
clockwise direction is necessary for a stable adjustment
of the crystal oscillator. If this results in reduced out­
put, continue turning the screw counterclockwise until
a second peak is reached. If this second peak signal is
greater than the signal heard at the three-quarters
counterclockwise turn, leave the tuning screw in this
position. If the signal is less, return the tuning screw
to the three-quarters position. Check after completing
steps (k) and (I) below.
AN
1 6-40SCR624-2
(k) Turn the signal generator "OUTPUT CON­
TROL" to "MIN." Place the "OUTPUT STEPS" con­
trol in position 1 or 2. Turn the "OUTPUT CON­
TROL" clockwise until the signal is j ust audible.
(I) Adjust the receiver tuning controls and the
signal generator "MEGACYCLES" dial control for
maximum audio output. Rotate the "OUTPUT CON­
TROL" counterclockwise, if necessary, to keep the
peaked output at a low level in the headset. The final
setting of the receiver tuning controls should be near
the calibrated settings for the desired frequency.
( 8 ) TUNING OF REMAINING
CHANNELS ( USING CRYSTAL
IN SIGNAL GENERATOR) .
.
IMPORTANT
Before selecting channel "B," hold the tuning
controls with the fingers and tighten the lock
nuts just enough to exert a slight pressure on
the cam pile-up. While doing this, make cer­
tain that the audio output level remains con­
stant.
(a) Select channel "B" on the control box and
completely loosen all tuning control lock nuts.
(b) Follow the same tuning procedure outlined
for channel "A" in paragraph 9.d. ( 7 ) , this section.
N ote
The tuning instructions for channel "A" will
hold good for channel "B," only if the letter
"B" is substituted for "A" wherever the crystal,
the channel, and the oscillator plate-coil tuning
screw are mentioned. This note likewise ap­
plies when tuning channels "C" and "D."
( c) Tune channels "C" and
"D"
in like manner.
(d) Press the channel-release push button and
tighten the two receiver tuning-control lock nuts by
turning them tightly clockwise with the fingers. If a
tool is being used, do not tighten lock nuts exces­
sively.
( e) Check all channels for satisfactory receiver
output.
( 9 ) TUNING OF REMAINING CHANNELS
( USING SIGNAL GENERATOR
MASTER OSCILLATOR) .
IMPORTANT
Before selecting channel "B," hold the tuning
controls with the fingers and tighten the lock
nuts just enough to exert a slight pressure on
the cam pile-up. While doing this, make sure
that the audio output level does not change.
(a) Select the channel "B" push button on the
radio control box and completely loosen all tuning
control lock nuts.
(b) Follow the same tuning procedure outlined
for channel "A" in paragraph 9d( 7 ) , this section.
Section V
Paragra p h
9dI7J1kl-9dI 1 1 lId
Note
The tuning instructions for channel "A" will
hold good for channel "B" only if the letter
"B" is substituted for "A" wherever the crys­
tal, the channel, and the oscillator plate-coil
tuning screw are mentioned. This note like­
wise applies when tuning channels "C" and
"D." Tune channels, "C" and "D" in like
manner.
( c) Press the channel-release push button and
tighten the two receiver tuning-control lock nuts by
turning them tightly clockwise with the fingers. If a
tool is being used, do not tighten the lock nuts ex­
cessively.
(d) Check all channels for satisfactory receiver
output.
( 10) TUNING OF SINGLE CHANNEL OUT
OF ADJUSTMENT.-If the channel is known to be
out of adjustment, it may be tuned without disturbing
the other channels as, follows:
(a) Select the channel on the control box cor­
responding to the channel preceding the desired chan­
nel in the sequence "A," "B," "C," "D." In other
words, if channel "B" is being retuned, press, button
"A" ; if channel "A" is being retuned, press push button
"D," and so forth.
(b) Press the channel-release push but;ton.
(c) Loosen the receiver tuning-control lock nuts,
keeping a slight pressure on the cam pile-up.
(d) Select the channel-selector push button for
the desired channel and completely loosen all tuning
control lock nuts.
( e) Tune the desired channel (see par. 9d( 6 ) ,
( 7 ) , this sec. ) depending o n whether or not a crystal
is used in the signal generator. Ignore reference to
channel "A" and substitute the applicable letter.
(f) Press the channel-release push button.
(g) Tighten the receive tuning-control lock nuts
with the fingers. If a tool is being used, do not tighten
lock nuts excessively.
( h) Press the channel-release push button to re­
select the channel j ust tuned.
(i) Recheck all channels for satisfactory receiver
output.
(a) Be sure that the tuning control lock nuts
are tightened.
( 1 1 ) TUNING CHECKS.
(b) Tune in a signal from a source such as Test
Equipment IE-36 or Test Equipment IE- 19- ( * ) .
( c) Rotate either tuning control clockwise and
then counterclockwise. If there is a decrease in signal
as the control is rotated in either direction, the receiver
is tuned correctly.
*
Refers to any issue.
5 -5 1
Section V
Paragra p h 9dn 1 Hd)-gen Hi)
AN 1 6- 405 CR624-2
(d) If the signal increases as the tuning control
is rotated in either direction, tune the receiver as di­
rected in paragraph 9d( 6) , ( 7 ) , ( 8 ) , this section.
IMPORTANT
Never shut off the equipment with the shifter
slides disengaged, since this will result in fail­
ure to turn on the transmitter and receiver
if one particular channel is selected on the
control box.
( 1 2 ) RECEIVER "AUDIO" CONTROL
ADJUSTMENT.
(a) The receiver output transformer 296 is pro­
vided with three impedance taps: terminal No. 5 , 50
ohms; No. 6, 300 ohms, and No. 7, 4000 ohms. In
some equipments, the output lead is connected to
terminal No. 6 and in others to terminal No. 7. In
Radio Receiver BC-624-C, the 80-ohm tap is terminal 4
and the 800-ohm tap is terminal 5 on transformer 200.
(b) The exact setting of the "AUDIO" volume
(see fig. 4-1 0) depends upon the head set being used
and the volume desired by the operator. However,
when using Radio Receiver BC-624-A, never advance
the "AUDIO" control on the receiver beyond three­
quarters of seven-eighths of its maximum rotation.
When using Radio Receiver BC-624-AM or BC-624-C,
set the "AUDIO" control in the extreme clockwise
position.
(d) If the operator desires more volume and
the audio output is connected to terminal No. 6 of trans­
former 296, transfer the output connection to ter­
minal No. 7.
( 1 3 ) "RELAY" OR "SQUELCH" CONTROL
ADJUSTMENT.
(a) If the "RELAY" or "SQUELCH" control
adjustment is to be made on the receiver, make the
adjustment with the antenna connected, the equipment
operating on any tuned channel and no signal being
received.
(b) Rotat", the "RELAY" or "SQUELCH" con­
trol (see fig. 4-1 0) to the extreme clockwise position.
Turn it slowly counterclockwise until a noticeable
drop in noise results. . Continue the counterclockwise ·
rotation for a very small fraction of a turn .
e.
RECEIVER TUNING USING TEST
EQUIPMENT IE-36 AND A
SUITABLE HEADSET.
( 1 ) TUNING CHANNEL "A."
(a) Loosen the Dzus fasteners pinning the re­
ceiver cover to the center cover, lift the receiver cover
slightly and slide it away from the control panel.
(b) If crystals have not been previously inserted,
install the proper crystal in the crystal socket for
.receiver channel "A." ( See par. 9c ( 3 ) , this sec. )
(c) Set up Test Equipment IE-36 as described
in paragraph 9b, this section.
(d) Turn the "OFF A-B-C-D" switch to Con5-52
trol Unit BC- 1 303 to "D." This is the channel pre­
ceding the channel to be tuned ( channel A )
( e) Press the channel-release push button 426
located on Rack FT-244-A. (See fig. 4-20.)
(f) Loosen the two receiver tuning-control lock
nuts 5 and 6 by turning them counterclockwise. Tighten
the two lock nuts just enough to exert a slight pressure
on the cam pile-up, otherwise vibration may change
the position of the cam, introducing considerable set-up
error.
(g) Turn the "OFF A-B-C-D" switch to "A"
and completely loosen tuning control nuts 5 and 6.
After allowing about one minute for the receiver
vacuum tubes to warm up, place the "SEND-REC.­
SEND" switch on Control Box BC- 1 203 to the "REC."
position. Turn the noise limiter switch (part of the
"SQUELCH" control) off for Radio Receiver BC-624-C.
"
"
.
IMPORTANT
Avoid tuning to an undesired harmonic by
making certain that the receiver r-f and oscil­
lator tuning controls 5 and 6 are turned to the
desired frequency on the calibration plate. An
error of more than 3 megacycles may mean
that the receiver is operating approximately
8 megacycles removed from the operating
frequency.
(b) Turn on the "SIG. GEN." switch located
on the left end of the control unit, and rotate the
"AUDIO" and "RELAY" controls (see fig. 4-1 0) to
their maximum . clockwise rotation positions.
(i) Starting from the extreme clockwise posi­
tion, slowly turn the channel "A" oscillator plate-coil
tuning screw adjustment (see fig. 4-7) counterclock­
wise so that about three to five threads of the screw
protrude from the coil-mounting insert. The higher
the crystal frequency the further the plate-coil screw
must be backed out of the coil-mounting insert, thus
obtaining the necessary inductance to permit the oscil­
lator to start. When the oscillator starts, a signal
should be heard in the headset .
(i) If there is no audible signal, simultane­
ously adjust the receiver r-f and oscillator tuning con­
trols 5 and 6 slightly, and if necessary, turn the chan­
nel "A" oscillator plate-coil tuning screw still further
counterclockwise until the signal is heard. (See figs
4-7 and 4-8.) When the signal is heard, rotate the
oscillator plate-coil tuning screw counterclockwise to a
position at least three-quarters of a turn past the point
at which the oscillator starts� The additional three­
quarters of a tum is required for a stable adjustment
of the crystal oscillator. If the output is decreased
appreciably by this extra rotation, continue turning the
screw counterclockwise until a second peak is reached.
If this secon d peak signal is greater than the signal
heard at the three-quarters counterclockwise turn, leave
the tuning screw in this position. If the signal is less,
return the tuning screw to the three-quarters position.
( Final adjustment should be made on a weaker signal
AN 1 6-40SCR624-2
For Radio Receivers BC-624-AM modified for
suppression of impulse noise, the signal heard
in the head set will be considerably less in
volume than before modification. Most accu­
rate tuning is obtained if controls 5 and 6 are
peaked using only circuit noise or hiss and
with the "SIG. GEN." switch on the control
unit in the "OFF" position. This "fine" ad­
justment is to be made after "rough" tuning
with the "SIG. GEN." switch in the "ON"
position.
( 2 ) TUNING OF REMAINING CHANNELS.
(a) Turn the "OFF A-B-C-D" switch on Con­
trol Unit BC- 1 303 to "B" and completely loosen all
tuning-control lock nuts.
IMPORTANT
Before turning the switch to "B," hold the
tuning controls with the fingers and tighten
the lock nuts 5 and 6 j ust enough to exert a
slight pressure on the cam pile-up. While
doing this, make certain that the audio output
level remains constant. This is accomplished
by readjusting the receiver tuning controls.
(b) Follow the same tuning procedure outlined
for channel "A." ( See par. 9d, this sec . )
Note
The tuning instructions for channel "A" will
apply to channel "B" only if the letter "B" is
substituted for "A" wherever the crystal, the
channel, and the oscillator plate-coil tuning
screw are mentioned. This note likewise ap­
plies when tuning channels "C" and "D."
( c) Tune channels "C" and "D" in a like man­
ner; then press · the channel-release push button 426
and tighten the two receiver tuning-control lock nuts
5 and 6 by turning them tightly clockwise with the
fingers. If a tool is being used, do not tighten lock
nuts excessively. Recheck all channels for satisfac­
tory receiver output. With slight movement of the
receiver tuning controls against the detent, maximum
signal should be obtained in the rest position. �is
completes the tuning of the receiver.
( 3 ) PROCEDURE FOR TUNING ONE CHAN­
NEL ONLY.-If one channel is out of adjustment,
it may be tuned without disturbing the other channels.
(a) Turn the "OFF A-B-C-D" switch on the
control unit to the channel preceding the channel to be
tuned in the sequence "A," "B," "C," "D." For ex­
ample, if channel "B" is /being retuned, turn the
switch to "A," if channel "A" is being retuned, turn
switch to "D," and so forth.
(c) Loosen the two receiver tuning-control lock
(b) Press the channel-release push button 426.
by removing the alligator clip on Cord CD- 1 1 70 from
the center pin of Socket SO- 1 5 3 of the rack.)
N ote
Secti o n V
Paragra p h gel1 )(;'-91(2 '
nuts.
(d) Turn the "OFF A-B-C-D" switch to the
desired channel.
(e) Tune the desired channel as described in
paragraph 9.d., this section, ignoring reference to chan­
nel "A" and substituting the applicable letter.
(f) Press the channel-release push button.
(g) Tighten the receiver tuning-control lock
nuts.
(h) Press the channel release push button to
re-select the channel j ust tuned.
IMPORTANT
Never shut the radio set off when the shifter
slides of the transmitter-receiver assembly are
disengaged since this will result in failure to
turn on the transmitter and receiver if one
particular channel is selected on the "OFF
A-B-C-D" switch on Control Unit BC- 1 303.
(4) RECEIVER "AUDIO " CONTROL ADJUST­
MENT.-The correct setting of the "AUDIO" control
236 depends on the type of headset being used and the
volume desired by the operator. However, for Radio
Receiver BC-624-A never advance the "AUDIO" con­
trol beyond three-quarters or seven-eighths of its maxi­
mum rotation. At full volume exceSsive distortion oc­
curs with strong signals. When using Radio Receiver
BC-624-AM or BC-624-C set the audio control to the
extreme clockwise position. If the operator desires
more volume and the audio output is connected to
terminal No. 6 of transformer 296, transfer the output
connection to terminal No. 7. (This reference number
appears near the transformer in the receiver. )
( 5 ) RECEIVER "RELAY" OR "SQUELCH"
CONTROL ADJUSTMENT.
(a) Make this last adjustment on the receiver
with the antenna connected, the equipment operating
on any tuned channel, and no signal being received.
(b) Rotate "RELAY" control (237) to the_ ex­
treme clockwise position (do not operate noise limiter
switch on Radio Receiver BC-624-C) and then turn it
slowly counterclockwise until the noise ceases and con­
tinue the counterclockwise rotation for a very small ·
fraction of a turn.
f. TESTING REMOTE (PRESS-TO-TALK )
OPERATION USING TEST EQUIPMENT
IE-36.
( 1 ) Plug Control Unit BC- 1 303 into socket 4 1 7
o f the rack and Phantom Antenna A-29 into Socket
SO- 1 53, throw "T-R-REM" switch ( 107) on the con­
trol unit to "REM."
( 2 ) With the switch in this position, test the re­
ceiver with head set and buzzer to make certain that
it is operating.
5-53
S e c t i o n s V-VI
Paragra p h 9fI21-VI- l a-3
AN
1 6- 40S CR624-2
extreme clDckwise pDsitiDn, it must be ad­
justed befDre the receiver is used fDr com­
municatiDns. TO' adjust the "SQUELCH" or
"RELAY" control, first turn the cDntrol
counterclDckwise until the snap of a switch
is heard. Then adjust the "SQUELCH" Dr
'
"RELAY" CDntrol as described in e ( 5 ) , this
sectiDn.
CAUTION
When RadiO' Receiver BC-624-C is tuned with
a buzzer Dr similar radiO' frequency SDurce,
turn the "SQUELCH" Dr "RELAY" cDntrDI
clockwise until the snap Df a switch is heard.
Then follow usual tuning prDcedure. If the
"SQUELCH" Dr "RELAY" control is in the
SECIION VI
1.
SUPPLEMENIARY DAIA
CHARACTERISTICS OF RAD I O SET SCR-624-A.
a.
FREQUENCY RANGE.-The frequency range is
100 to' 1 5 6 megacycles.
h. POWER SUPPLY.
( 1 ) The input to' Rectifier RA-62-B Dr RA-62-C is
1 10 vDlts a-c Dr 220 VDltS a-c.
( 2 ) The Dutput is positive 300 vDlts, negative 1 5 0
vDltS and positive 1 3 volts.
c. INPUT CURRENT REQUIREMENTS.-The in­
put current requirements are 2 . 6 amperes, 1 10 vDltS fDr
transmission and 2 . 7 amperes, 1 10 volts fDr reception.
d. TYPE OF MODULATION.-The radiO' set is
amplitude mDdulated.
e. METHOD O F MODULATION.-Plate mDdula­
tion is used in RadiO' Set SCR-624-A Dr SCR-624-B.
f. BEAT FREQUENCY OSCILLATOR.-RadiO' Set
SCR-624-A Dr SCR-624-B has nO' beat frequency Dscil­
lator.
g. CRYSTAL FILTER.-The radiO' set has nO' crys­
tal filter.
h. SQUELCH CIRCUIT CHARACTERISTICS. ­
The sensitivity is 0-20, 0-2 50 microvDlts for RadiO' Re­
ceiver BC-624-A and 0-6, 0-20 fDr RadiO' Receiver
BC-624-AM Dr BC-624-C.
Quantity
2
*1
1
tl
1
:I:l
5 - 5 4-6 - 0
Army-Navy Type
Tube
Tube
Tube
Tube
Tube
Tube
Tube
Tube
Tube
Tube
Tube
Tube
Tube
Tube
Tube
JAN-832
JAN-832
Jan- 12A6
JAN- 1 2A6
JAN- 12J5GT
JAN- 12C8
JAN- 12A6
JAN-6G6G
JAN-6SS7
JAN-6SS7
JAN-9002
JAN-9003
JAN-9003
JAN-9003
JAN- 12AH7GT
VT Numbers
VT- 1 l 8
VT- 1 18
VT- 1 34
VT. 1 34
VT- 1 3 5
VT- 169
VT- 134
VT- 198A
VT- 199
VT- 199
VT-202
VT-203
VT-203
VT-203
VT-207
2.
TYPES O F RADIO JAMM I N G .
Types Df j amming likely to' be emplDyed by the
enemy are the fDllDwing:
a. "Spark" j amming, the . familiar type Df nDise Db­
tained frDm small electric motDrs, razors, ignition sys­
tems, et cetera.
h. "Sweep-thrDugh" jamming, the result Df sweeping
a carrier back and fDrth acrDSS a frequency band at a
relatively rapid rate ( 100 to' 600 cycles per secDnd) .
The resulting nDise i s much like that D f an airplane
engine.
" Stepped tDne" j amming, a mDnDtDnDUS repeti­
c.
tion Df three to' five audiO' tones which resemble the
Scotch bagpipe. The Germans use this regularly.
d. "NDise" j amming, sounding the same as nDise
which is heard when the gain is turned up Dn a radiO'
receiver that is nO't tuned to' a signal. It may easily
be mistaken fDr receiver nO'ise.
e . CDmbinatiDn Df any Df the above types Df j am­
ming.
3. TUBE COMPLEMENT.
The tubes used in RadiO' Set SCR-624-A Dr SCR624-B are listed belDw.
Function
2nd Harmonic amplifier
R-F power amplifier
Harmonic amplifier
Modulator
A- F amplifier
2nd Detector AVC a-f amplifier
Au d io output
Transmitter oscillator
R-F indicator
Speech amplifier
Harmonic generator
R-F amplifier
Mixer
Harmonic amplifier
Oscillator
AN 1 6-40SCR624-2
Quantity
Tube
Tube
Tube
Tube
Tube
§l
3
II I
1
VI Numbers
Army-Navy Type
1st audio and AVC delay
I-F amplifier
AVC delay diode noise limiter diode
Rectifier
Rectifier
§Included in Radio Receiver BC-624-C.
II lncluded in Radio Receiver BC-624-AM and BC-624-C.
*Not included in Radio Receiver BC-624-C.
tIncluded in Radio Receiver BC-624-C.
tNot included in some radio transmitter.
4.
Note
SUPPLEMENTARY PARTS LIST.
A supplementary parts
624-C is given below.
list for Radio Receiver
TABLE 6 - 1 .
-
202· 1 7
202- 1 8
202· 19
202-20
202·2 1
202-22
202-2 3
202-25
202·26
202·2 7
202-28
202-29
203· 1
2 0 3- 2
202-30
2 0 3- 4
203-3
204
205
2 06- 1
2 06-2
206·4
206·5
206·3
206· 7
206-6
2 06·8
206·9
206- 1 0
206- 1 1
2 06· 1 2
The following table is for reference purposes
only although the parts will be furnished as
BC-
spares.
SU PPLEMENTARY PA RTS LIST FOR RADIO RECEIVER BC . 6 2 4 . C .
Reference
Number
20 1
2 0 2- 1
202-2
202-3
202-4
20 1.5
202-6
202-7
202-8
202-9
202- 10
202- 1 1
202- 12
202- 1 3
20 2 1 4
202- 1 5
202· 16
(Cont'd)
Function
VT-207
VT-209
VT-2 14
VT- 126
VT-244
JAN- 12AH7GT
JAN- 12SG7
JAN- 12H6
JAN-6X5GT
JAN-5U4G
Sectio n VI
Paragra p h 4-Ta b l e 6- 1
Description
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
. Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor :
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor :
Capacitor:
Capacitor:
micromicrofarad
micromicrofarad
680 micromicrofarad
6 80 micromicrofarad
680 micromicrofarad
680 micromicrofarad
680 micromicrofarad
680 micromicrofarad
680 micromicrofarad
680 micromicrofarad
680 - micromicrofarad
680 micromicrofarad
680 micromicrofarad
680 micromicrofarad
680 micromicrofarad
680 micromicrofarad
680 micromicrofarad
680 micromicrofarad
680 micromicrofarad
680 micromicrofarad
680 micromicrofarad
680 micromicrofarad
680 . micromicrofarad
680 micromicrofarad
680 micromicrofarad
680 micromicrofarad
680 micro microfarad
680 micromicrofarad
680 micromicrofarad
680 micromicrofarad
47 micromicrofarad
47 micromicrofarad
47 micromicrofarad
47 micromicrofarad
1 5 micromicrofarad
2 2 0 micromicrofarad
6800 micromicrofarad
6800 micromicrofarad
6800 micro microfarad
6800 micromicrofarad
6800 micromicrofarad
6800 micromicrofarad
68QO micromicrofarad
6800 micromicrofarad
6800 micromicrofarad
6800 micromicrofarad
6800 micromicrofarad
6800 micro microfarad
10
680
-
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
Function
20%
20%
20%
2 0%
2 0%
20%
20%
20%
20%
20%
20%
20 %
20%
20%
2 0%
20%
20%
20%
200/v
2 0%
20%
2 0%
20%
2 0%
2 0%
20%
20%
2 0%
2 0%
2 0%
2 0%
20 %
2 0%
2 0%
20%
20%
20%
2 0%
20 %
20 %
2 0%
20 %
2 0%
20%
2 0%
20%
2 0%
2 0%
R-F grid coupling
R-F cathode bypass
R-F AVC filter
R-F screen bypass
R-F plate bypass to cathode
R-F plate bypass to ground
Mixer cathode bypass
Mixer screen bypass
Harmonic amplifier B + filter
Harmonic amplifier plate bypass to cathode
Harmonic amplifier plate bypass to ground
Harmonic amplifier cathode bypass
Harmonic amplifier screen bypass
Harmonic generator plate bypass
Harmonic generator plate bypass
Harmonic generator cathode bypass
R-F B + filter
Audio B + filter
R-F heater bypass
Mixer heater bypass
Mixer heater bypass
Harmonic amplifier heater bypass
Harmonic amplifier heater bypass
Harmonic generator heater bypass
2nd I-F suppressor bypass
3rd I-F suppressor bypass
Oscillator plate coil bypass
Limiter cathode bypass
Audio compensating
Diode R-F bypass
Mixer grid coupling
Harmonic amplifier grid coupling
AVC diode coupling
2nd audio R-F bypass
Oscillator plate resonator
Harmonic generator grid coupling
Oscillator plate bypass
Oscillator cathode bypass
Mixer plate bypass
1st I-F AVC filter
1 st I-F cathode filter
1 st I-F screen bypass
1st I-F plate bypass
2nd !-F AVC filter
2nd I-F cathode bypass
2 nd I-F screen bypass
2nd I-F plate bypass
3rd I-F cathode bypass
6· 1
AN 1 6-40SCR624-2
Secti o n VI
Paragra p h 4-Ta b l e 6- 1 (Cont'd)
TABLE 6 - 1 .
SUPPLEMENTA RY PARTS LIST FOR RADIO RECEIVER BC -62 4 -C
Reference
Number
206- 1 3
206- 1 4
206- 1 5
206- 16
206- 1 7
206- 19
206-20
206-2 1
206-22
206-24
206-2 5
206-26
206-27
207- 1
207-2
207-3
207-4
207-5
207-6
207-7
207-8
208- 1
208-2
208-3
208-4
208-5
208-6
208-7
208-8
2 10
2 1 l-3A
2 1 l-3B
2 1 1-3C
2 1 1-4A
2 1 1-4B
2 1 1-4C
2 12-A
2 12-B
2 12-C
2 12-D
213
2 14
2 16-A
2 16-B
2 16-C
2 17-A
2 17-B
2 18- 1
2 18-2
2 18-3
2 18-4
2 18-5
22 1
222
223
224
225
226
227- 1
227-2
227-3
227-4
228- 1
228-2
228-3
6-2
Description
}
}
micromicrofarad
micromicrofarad
micromicrofarad
micromicrofarad
micromicrofarad
micromicrofarad
micromicrofarad
micro microfarad
micromicrofarad
micro microfarad
micromicrofarad
micromicrofarad
micromicrofarad
micromicrofarad
micromicrofarad
micromicrofarad
micromicrofarad
micromicrofarad
micromicrofarad
micromicrofarad
micromicrofarad
micromictofarad
micromicrofarad
micromi crofarad
micromicrofarad
micromicrofarad
micromicrofarad
micromicrofarad
micromicrofarad
micromicrofarad
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
1Con't) .
Function
20%
20%
20%
20%
20%
20%
20%
20%
20%
20%
20%
20%
20%
20%
20%
20%
20%
20%
20%
20%
20%
10%
10%
10%
10%
10%
10%
10%
10%
20%
3rd I-F screen bypass
3rd I-F plate bypass
B + bypass
Audio squelch grid bypass
Audio coupling
1st I-F heater bypass
2nd I-F heater bypass
3rd I-F heater bypass
Oscillator and audio squelch heater bypass
1st audio grid coupling
1st audio cathode coupling
3rd audio grid coupling
Detector cathode r-f bypass
Mixer plate resonator
1st I-F grid resonator
1st I-F plate resonator
2nd I-F grid resonator
2nd I-F plate resonator
3rd I-F grid resonator
3rd I-F plate resonator
Detector diode resonator
Mixer plate resonator
1st I-F grid resonator
lst I-F plate resonator
2nd I-F grid resonator
2nd I-F plate resonator
3rd I-F grid resonator
3rd I-F plate resonator
Detector diode resonator
Audio diode bypass
Audio diode cathode bypass
3 x .1
AVC filter
2nd audio screen bypass .
lst audio bypass
3 x 1 microfarad
Noise limiter filter
2nd I-F AVC filter
1 microfarad
Audio B filter
Audio B filter
4 microfarad
2nd audio cathode bypass
microfarad
3rd audio cathode bypass
2 microfarad
Capacitor 1 microfarad
R-F and mixer heater bypass
Capacitor: 82 micromicrofarad + 10%
Bridge balancing
Capacitor
R-F grid .tuning
Capacitor
R-F plate tuning
Capacitor
Mixer grid tuning
Harmonic amplifier plate tuning
Capacitor ·
Harmonic generator plate tuning
Capacitor
Capacitor
R-F grid trimmer for 2 16-A
R-F plate trimmer for 2 16-B
Capacitor
Mixer grid trimmer for 2 16-C
Capacitor
Harmonic amplifier plate trimmer for 2 1 7-A
Capacitor
Harmonic generator plate trimmer for 2 1 7-B
Capacitor
Antenna coupling coil
Coil: One turn No. 14 tinned copper wire
R-F grid resonator
Coil: Two turns No. 14 tinned copper wire
R-F plate resonator
Coil: Two turns No. 14 tinned copper wire
Mixer grid resonator
Coil: Two turns No. 14 tinned copper wire
Harmonic amplifier plate resonator
Coil: Two turns No. 14 tinned copper wire
Harmonic generator plate resonator
Coil : Two turns No. 14 tinned copper wire
Coil: 23 turns No. 26 enameled wire, permeabilityOscillator plate resonator "A"
tuned
Coil: Same as 227 ±
Oscillator plate resonator "B"
Coil : Same as 227 ±
Oscillator plate resonator "C"
Coil: Same as 227 ±
Oscillator plate resonator "D"
Coil: 10 turns No. 22 enameled wire, threaded form,Mixer plate resonator
part 2 9 1 .
Coil: Same a s 228- 1, part o f 2 9 1
1 st I-F grid resonator
Coil: Same a s 228- 1, part o f 292
1st I-F plate resonator
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
6800
6800
6800
6800
6800
6800
6800
6800
6800
6800
6800
6800
6800
60
60
60
60
60
60
60
60
15
15
15
15
15
15
15
15
330
{
{
Secti on VI
Paragra p h 4--Ta ble 6- 1 ( Cont'd)
AN 1 6-40S C R624-2
TABLE 6- 1 .
Reference
Number
2 30-3
2 30-4
231
2 32
233- 1
2 33-2
2 33-3
233-4
2 38-A
2 38-B
2 39
240
24 1-2
241-3
241-4
24 1-5
243- 1
243-2
243-3
243-4
243-7
243-8
243-9
243- 10
244- 1
244-2
244-3
244-4
248
249- 1
249-2
249-3
249-4
250
251
252-1
253-1
2 5 3-2
255- 1
255-2
256
257- 1
257-2
2 58-2
2 58-3
260
261
262- 1
263- 1
263-2
263-3
263-4
264- 1
264-3
265
Function
Description
228-4
,,'� 28-5
228-6
228-7,
228-8
2 30- 1
2 30-2
2 34- 1
2 34-2
2 35- 1
2 35-2
2 36
SUPPLEMENTARY PARTS L IST FOR RADIO RECEIVER BC -624 -C (Con't) .
}
Coil: Same as 228- 1, part of 292
Coil: Same as 228- 1, part of 293
Coil : Same as 228. 1, part of 293
Coil: Same as 228- 1, part of 294
Coil: Same as 228- 1, part of 294
Resistor: 12,000 ohms ± 10% ; 1/4 watt
Resistor: 12,000 ohms ± 10% ; 1f4 watt
Resistor: 12,000 ohms - 10% ; 1f4 watt
Resistor: 1 2,000 ohms - 10% ; V4 watt
Plug
Plug board assembly
Resistor: 1 80,000 ohms ± 10% ; V2 watt
Resistor: IS0,000 ohms ± 10% ; V2 watt
Resistor: IS0,000 ohms ± 10% ; V2 watt
Resistor: 180,000 ohms ± 10% ; 1/2 watt
Resistor: 160,000 ohms ± 5 % ; 1/2 watt
Resistor: 160,000 ohms ± 5 % ; 1/2 watt
1 ,000 ohms ± 5 % ; V2 watt
Resistor:
1 ,000 ohms ± 5 % ; V2 watt
Resistor:
Potentiometer: 150,000 ohms
Potentiometer 5000 ohms w / switch
Resistor: 680 ohms ± 10% ; 1f2 watt
Resistor: 3.3 megohms ± 10% ; V2 watt
Choke
Choke
Choke
Choke
Oscillator and audio squelch
1st J-F
2nd J-F
3rd J-F
Det. and N. L.
AVC and 2nd audio
AVC delay and 1st audio
3rd audio
R-F amplifier
Mixer
Harmonic amplifier
Harmonic generator
Frequency shifter
Screw
Screw
Screw
Screw
Spring
Resistor: 470,000 ohms ± 20% ; 1/4 watt
Resistor: 100,000 ohms ± 20% ; 1,4 watt
Resistor: 330,000 ohms ± 5 % ; V4 watt
Resistor: 330,000 ohms ± 5 % ; 1f4 watt
Resistor: I.S megohms ± 20% ; 1,4 watt
Resistor: I.S megohms ± 20% ; 1,4 watt
Resistor:
1 ,000 ohms ± 5 % ; 1,4 watt
Resistor: 330,000 ohms ± 10% ; 1f4 watt
Resistor: 330,000 ohms ± 10% ; 1f4 watt
Resistor: 6S0,000 ohms ± 20% ; 1/2 watt
Resistor: 680,000 ohms ± 20% ; V2 watt
Resistor: 27,000 ohms ± 20% ; 1f4 watt
Resistor:
1,200 ohms ± 5 % ; 1,4 watt
Resistor: 560,000 ohms ± 1 0 % ; 1,4 watt
4,700 ohms ± 20% ; 1f2 watt
Resistor:
Resistor:
4,700 ohms ± 20% ; V2 watt
Resistor:
4,700 ohms ± 20% ; 1/2 watt
Resistor:
4,700 ohms ± 20% ; V2 watt
Resistor: 10,000 ohms ± 20% ; 1f2 watt
Resistor: 10,000 ohms ± 20% ; V2 watt
Resistor:
2,700 ohms ± 5 % ; V2 watt
{
2nd I-F grid resonator
2nd I-F plate resonator
3rd I-F grid resonator
3rd I-F plate resonator
Detector diode resonator
R-F plate filter
R-F plate filter
Harmonic amplifier plate filter
Harmonic amplifier plate filter
Receiver connector plug
Receiver input plug
1st I-F screen bleeder
1st I-F screen bleeder
2nd I-F screen bleeder
2nd I-F screen bleeder
Audio squelch bleeder
Audio squelch bleeder
3rd audio cathode bias
3rd audio cathode bias
Audio volume control
Squelch sensitivity control
Noise limiter switch
A VC delay cathode bias
3rd audio inverse feedback
B + R-F choke
B + R-F choke
2nd audio grid choke
3rd i-f B + isolation choke
Socket for jAN- 12AH7GT
Socket for jAN- 12SG7
Socket for jAN- 12SG7
Socket for jAN- 12SG7
Socke� for jAN- 12H6
Socket for JAN- 12CS
Socket for jAN- 12AH7-GT
Socket for jAN- 12A6
Socket for jAN-9003
Socket for jAN-9003
Socket for jAN-9003
Socket for jAN-9002
Frequency shifter
Red mounting screw
Red ' mounting screw
Red mounting screw
Red mounting screw
Spring for tube holder
R-F stage grid leak
R-F stage AVC filter
R-F stage cathode bias
Harmonic amplifier cathode bias
Mixer grid leak
Harmonic amplifier grid leak
Mixer cathode bias
Mixer screen dropping
2nd audio compensating
AVC filter
3rd audio grid leak
Harmonic generator plate filter
Harmonic generator cathode bias
Harmonic generator grid leak
Mixer plate filter
1st I-F plate filter
2nd I-F plate filter
3rd I-F plate filter
Oscillator plate filter
Audio and squelch filter
Oscillator cathode bias
6-3
Secti o n VI
AN
P a ra g ra p h 4-Ta b l e 6 - 1 -5 Table 6-2
TABLE 6 - 1 .
SU PPLEMENTARY PARTS LIST FOR RADIO RECEIVER BC-624-C ( Con't ) .
Reference
Number
266-4
267- 1
267-2
267-4
267-5
267-7
267-8
267-9
267- 1 0
269-2
269-3
2 7 1-3
272- 1
2 7 3-2
2 73-3
i74- 1
2 74-3
275-4
2 76- 1
2 76-2
277-2
278- 1
280-2
280-3
280-4
280-5
28 1-2
281-3
2 8 1 -4
283
284
285
286 A, B, C,
& D
287
288
289
290
29 1
292
293
294
295
297
200
5.
1 6 -40S C R624-2
Description
Resistor:
Resistor:
Resistor:
Resistor:
Resistor:
Resistor :
Resistor:
Resistor:
Resistor:
Resistor:
Resistor:
Resistor:
Resistor:
Resistor:
Resistor:
Resistor :
Resistor:
Resistor:
Resistor:
Resistor:
Resistor:
Resistor:
Resistor :
Resistor:
Resistor:
Resistor:
Resistor:
Resistor :
Resistor:
Resistor:
Resistor:
Resistor:
Switch
270,000 ohms
100,000 ohms
100,000 ohms
1 00,000 ohms
100,000 ohms
100,000 ohms
100,000 ohms
100,000 ohms
100,000 ohms
2 70 ohms
2 70 ohms
82,000 ohms
120,000 ohms
5,600 ohms
5,600 ohms
2 . 2 megohms
2.2 megohms
470,000 ohms
1 8,000 ohms
1 8,000 ohms
1 ,800 ohms
1 , 500 ohms
1 megohm
1 megohm
1 megohm
1 megohm
1 5 0,000 ohms
1 50,000 ohms
1 50,000 ohms
180 ohms
8.200 ohms
1 5 ,000 ohms
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
10% ;
20% ;
1O%;
20% ;
10%;
10% ;
10% ;
10%;
10% ;
5'0/0 ;
5%;
10% ;
10% ;
10% ;
5%;
20% ;
20%;
10% ;
5%;
10%;
5%;
5%;
20% ;
10% ;
10% ;
10%;
10%;
10% ;
10%;
5%;
5%;
10% ;
Function
1/2
Vz
V2
V2
V2
Vz
1/2
1/2
V2
Vz
Vz
V2
V2
V2
V2
V2
1/2
Vz
Vz
V2
V2
Vz
V2
Vz
V2
Vz
V2
V2
V2
Vz
Vz
V2
watt
watt
watt
watt
watt
watt
watt
watt
watt
watt
watt
watt
watt
watt
watt
watt
watt
watt
watt
watt
watt
watt
watt
watt
watt
watt
watt
watt
watt
watt
watt
watt
Resistor: 7.5 ohms ± 10% ; V2 watt
Socket
Socket
Resistor: 1 0,000 ohms ± 10% ; V4 watt
Transformer
Transformer
Transformer
Transformer
Transformer
Variable capacitor assembly
12A6 to 4000 and 300 ohms
DI FFERENCES BETWEEN RADIO RECEIVERS
BC-624-A AND BC-624 -AM.
MO'st O' f the material prO'vided in RadiO' Receiver
BC-624-AM is alsO' used elsewhere in RadiO' 'Set SCRTABLE 6 - 2 .
2nd audio plate load
1st I-F AVC filter
1 st I-F screen voltage divider
2nd I-F AVC filter
2nd I-F screen voltage divider
Harmonic amplifier screen dropping
R-F screen dropping
3rd I-F screen dropping
3rd I-F screen dropping
1 st I-F cathode bias
3rd I-F cathode bia�
A VC diode load
Audio squelch compensating
A VC delay cathode bias
Audio squelch bleeder
Audio squelch coupling
Audio squelch filter
Audio squelch plate load
AVC delay
Audio diode filter
2nd audio cathode bias
Audio squelch cathode bias
AVC coupling
2nd audio screen dropping
2nd audio grid
2nd audio grid
Noise limiter filter
Noise limiter load
Crystal oscillator grid resistor
2nd I-F cathode bias
Audio squelch bleeder
1 st audio cathode load
Crystal switch
Test meter shunt
Rec. test milliameter socket
Crystal socket
Audio diode load
Mixer to ist I-F coupling
ist I-F to 2nd I-F coupling
2nd I-F to 3rd I-F coupling
3rd I-F to diode coupling
Audio input transformer
Capacitor assembly, r-f 2nd osc.
Output transformer
624-A. The material nO'w in the depO'ts may be used
to' service both RadiO' Receiver BC-624-A and BC624-AM . The fO'IlO'win table . shO'ws the difference be­
tween RadiO' Receiver BC-624-A and BC-624-AM.
DI FFERENCES BETWEE N RADIO RECEIVERS BC-62 4 -A A N D BC-624-AM
Reference Number
BC-624-A
206-23
209
2 1 1A
2 1 1B
2 1 1C
6-4
Description
BC-624-AM
2 1 1- 1 A
2 1 1-lB
2 1 1- 1 C
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
Capacitor:
6,800
100
1 00,000
100,000
100,000
1 00,000
100,000
100,000
micromicrofarads
micromicrofarads
micromicrofarads
micromicrofarads
micromicrofarads
micromicrofarads
micromicrofarads
micromicrofarads
Function
3rd I-F grid bypass
Audio diode bypass
1 st audio cathode bypass
1 st audio screen bypass
AVC filter
1st audio cathode bypass
1 st audio screen bypass
AVC filter
AN
TABLE 6 - 2 .
S e ction VI
P a ra g ra p h 5-Ta b l e 6- 2-6 Ta b l e 6-3
1 6-40S C R624-2
DI FFERENCES BETWEEN RADIO RECEIVERS BC-624-A AND BC-624 -AM (Cont' d ) .
Referen�e Number
BC-624-A
2 5 3-3
2 54-3
264
264- 1
264-2
271
2 7 1-2
272
2 72- 1
2 72-2
276
2 76- 1
2 76-2
279-3
2 79-4
280
Limiter filter
Limiter filter
2nd I-F grid bypass
Limiter cathode bypass
Limiter and AVC delay
Audio diode load
AVC delay
AVC delay
Oscillator plate filter
Oscillator plate filter
Audio diode load
3rd I-F screen dropping
Limiter filter
Audio squelch compensating
Audio squelch compensating
Limiter load
AVC delay
AVC delay
Audio diode load
Audio diode load
3rd I-F screen dropping
3rd I-F grid leak
Capacitor : 1 00,000 micromicrofarads
Capacitor: 100,000 micromicrofarads
Capacitor: 1 00,000 micromicrofarads
1 ,000 micromicrofarads
Capacitor:
Tube socket
Resistor: 1 00,000 ohms
330 ohms
Resistor:
6,800 ohms
Resistor:
Resistor: 10,000 ohms
Resistor: 10,000 ohms
Resistor: 1 0,000 ohms
Resistor: 82,000 ohms
Resistor: 82,000 ohms
Resistor: 120,000 ohms
Resistor: 120,000 ohms
Resistor: 1 20,000 ohms
Resistor: 1 8,000 ohms
Resistor: 1 8,000 ohms
Resistor: 1 8,000 ohms
Resistor: 47,000 ohms
Resistor : 47,000 ohms
Resistor: 1.0 megohms
2 1 1-2A
2 1 1-2B
2 1 1-2C
2 19
243-7
2 52-2
Fun�tion
Des�ription
BC-624-AM
6. C RYSTAL FREQUE N CY C HART.
The crystal frequencies and their corresponding carrier frequency are listed in the following table:
TABLE 6-3.
Crystal Frequen�y
Carrier
Kilo�ycles
Frequen�y
Trans.
Mega�ycles Re�eive
100.08
100.26
100.44
100.62
1 00.80
100.98
101.16
1 0 1 .34
1 0 1.52
1 0 1 .70
1 0 1 .88
102.06
102.24
102.42
102 .60
102.78
102.96
103. 14
103.32
103.50
103.68
, 103.86
1 04.04
104.22
104.40
104.58
104.76
104.94
8007.27
802 3.64
8040.00
8050.36
8072.7 3
8089.09
8 105.45
8 1 2 1 .82
8 1 38. 1 8
8 1 54.5 5
8 1 70.9 1
8 1 87.27
8203.64
8220.00
8236.36
8252.73
8269.09
8285.45
830 1 .82
8318.18
8334. 5 5
83 50.9 1
8367.27
8383.64
8400.00
8416.36
8432.73
8449.09
5 560.0
5 5 70.0
5 580.0
5 590.0
5600.0
56 10.0
5620.0
5630.0
5640.0
5650.0
5660.0
5670.0
5680.0
5690.0
5 700.0
5 7 10.0
5 720.0
5730.0
5 740.0
5750.0
5 760.0
5 770.0
5 780.0
5 790.0
5800.0
58 10.0
5820.0
5830.0
C RYSTAL FREQUENCY CHART.
Crystal Frequen�y
Carrier
Kilo�ycles
Frequency
Trans.
Mega�ycles Re�eive
105 . 1 2
105.30
105.48
105.66
105.84
1 06.02
106.20
106.38
106.56
1 06.74
1 06.92
107. 1 0
107.28
107.46
107.64
107.82
108.00
108. 18
108.36
1 08.54
1 08.72
1 08.90
1 09.08
1 09.26
109.44
1 09.62
109.80
109.98
8465.45
848 1 .82
8498. 1 8
8 5 14.55
85 30·n
8547.27
8563.64
8580.00
8596.36
86 1 2 . 7 3
8629.09
8645.45
866 1 .82
8678. 1 8
8694.5 5
87 10.9 1
8000.00
80 1 5 .00
8030.00
8045.00
8060.00
8075.00
8090.00
8 105.00
8 120.00
8 1 3 5.00
8 150.00
8 165.00
5840.0
5850.0
5860.0
5870.0
5880.0
5890.0
5900.0
59 10.0
5920.0
5930.0
5940.0
5950.0
5960.0
5970.0
5980.0
5990.0
6000.0
60 10.0
6020.0
6030.0
6040.0
6050.0
6060.0
6070.0
6080.0
6090.0
6 1 00.0
6 1 10.0
Crystal Frequen�y
Carrier
Kilo�ycles
Frequen�y
Trans.
Mega�ycles Re�eive
1 10 . 1 6
1 10.34
1 10.52
1 10.70
1 10.88
1 1 1 .06
1 1 1 .24
1 1 1 .42
1 1 1 .60
1 1 1 .78
1 1 1 .96
1 12 . 1 4
1 12.32
1 12.50
1 12.68
1 12 .86
1 1 3.04
1 1 3.22
1 1 3.40
1 1 3.58
1 1 3.76
1 1 3.94
1 14. 1 2
1 14.30
1 14.48
1 14.66
1 14.84
1 1 5.02
8 1 80.00
8 1 95 .00
82 1 0.00
8225.00
8240.00
8 2 5 5.00
8270.00
8285 .00
8300.00
8 3 1 5 .00
83 30.00
8345.00
8360.00
8375.00
8390.00
8405.00
8420.00
8435.00
8450.00
8465.00
8480.00
8495.00
85 10.00
8540.00
8525.00
8 5 5 5 .00
8570.00
8585.00
6 1 20.0
6 1 30.0
6 1 40.0
6 150.0
6 1 60.0
6 1 70.0
6 1 80.0
6 190.0
6200.0
62 10.0
6220.0
62 30.0
6240.0
62 50.0
6260.0
6270.0
6280.0
6290.0
6300.0
63 10.0
6320.0
6330.0
6340.0
6350.0
6360.0
6370.0
6380.0
6390.0
Crystal Frequen(y
Carrier
Kilo�ycles
Frequen�y
Trans.
Mega�ycles Re�eive
1 1 5.20
1 1 5.38
1 1 5.56
1 1 5 .74
1 1 5 .92
1 16 . 1 0
1 16.28
1 16.46
1 16.64
1 16.82
1 17.00
1 17 . 1 8
1 1 7.36
1 1 7.54
1 1 7.72
1 1 7.90
1 18.08
1 18.26
1 18.44
1 18.62
1 18.80
1 18.98
1 19. 1 6
1 19.34
1 19.52
1 19.70
1 19.88
1 20.06
8600.00
8 6 1 5 .00
8630.00
8645 .00
8660.00
8007.69
802 1.54
803 5 . 38
8049.2 3
8063.08
8076.92
8090.77
8 104.62
8 1 18.46
8 1 32.3 1
8 1 46. 1 5
8 160.00
8 1 73.85
8 1 87.69
820 1 . 5 4
82 1 5.38
8229.23
8243.08
8256.92
8270.77
8284.62
8298.46
8312.31
6400.0
64 10.0
6420.0
6430.0
6440.0
6450.0
6460.0
6470.0
6480.0
6490.0
6500.0
6 5 1 0.0
6520.0
6530.0
6540.0
6550.0
6560.0
6570.0
6580.0
6590.0
6600.0
66 1 0.0
6620.0
6630.0
6640.0
6650.0
6660.0
6670.0
6- 5
Sectio n VI
Para g ra p h 6-Ta ble 6-3
Crystal Frequency
Carrier
Kilocycles
Frequency
Trans.
Megacycles Receive
120.24
120.42
120.60
120.78
120.96
12 1 . 14
12 1.32
1 2 1 .50
1 2 1 .68
1 2 1 .86
122.04
122.22
122.40
122.58
122.76
122.94
123.12
123.30
123.48
123.66
123.84
124.02
124.20
124.38
124.56
124.74
124.92
125. 10
125.28
125.46
125.64
12 5.82
126.00
1 26. 18
126.36
126.54
126.72
126.90
127.08
127.26
127.44
127.62
127.80
127.98
128. 16
128.34
128.52
128.70
128.88
129.06
6-6
8326. 1 5
8340.00
8353.85
8367.69
838 1.54
8395.38
8409.23
8423.08
8436.92
8450.77
8464.62
8478.46
8492. 3 1
8506. 1 5
8520.00
8533.85
8547.69
856 1.54
8575.38
8589.2 3
8603.08
800 1.43
80 14.29
8027. 14
8040.00
8052.86
8065.7 1
8078.57
809 1 .43
8104.29
8 1 17.14
8 1 30.00
8142.86
8 155.7 1
8168.57
8181.43
8 194.29
8207. 14
8220.00
8232.86
8245.7 1
8258.57
827 1 .43
8284.29
8297. 14
8310.00
8322.86
8335.7 1
8348.57
836 1.43
6680.0
6690.0
6700.0
67 10.0
6720.0
6730.0
6740.0
6750.0
6760.0
6770.0
6780.0
6790.0
6800.0
68 10.0
6820.0
6830.0
6840.0
6850.0
6860.0
6870.0
6880.0
6890.0
6900.0
69 10.0
6920.0
6930.0
6940.0
6950.0
6960.0
6970.0
6980.0
6990.0
7000.0
70 10.0
7020.0
7030.0
7040.0
7050.0
7060.0
7070.0
7080.0
7090.0
7 100.0
7 1 10.0
7 120.0
7 1 30.0
7 140.0
7 1 50.0
7 160.0
7 1 70.0
TABLE 6-3.
AN 1 6-40SCR624-2
CRYSTAL FREQUENCY CHART
Crystal Frequency
Carrier
Kilocycles
Frequency
Trans.
Megacycles Receive
129.24
129.42
129.60
129.78
129.96
1 30. 14
130.32
1 30.50
1 30.68
1 30.86
1 3 1.04
1 3 1.22
1 3 1.40
1 3 1.58
1 3 1. 76
1 3 1 .94
1 32 . 1 2
1 32.30
132.48
132.66
1 32.84
1 33.02
1 33.20
1 33.38
133.56
133.74
1 33.92
1 34. 10
1 34.28
1 34.46
1 34.64
1 34.82
1 35.00
1 3 5 . 18
135.36
135.54
135.72
1 35.90
1 36.08
136.26
1 36.44
1 36.62
1 36.80
1 36.98
137.16
1 37.34
1 37.52
1 37.70
1 37.88
1 38.06
8374.29
8387. 14
8400.00
8412.86
8425.7 1
8438.57
845 1.43
8464.29
8477. 14
8490.00
8502.86
8 5 1 5.71
8528.57
854 1 .43
8554.29
8567. 14
8008.00
8020.00
8032.00
8044.00
8056.00
8068.00
8080.00
8092.00
8104.00
8 1 16.00
8 1 28.00
8 140.00
8 1 52.00
8 1 64.00
8 1 76.00
8 1 88.00
8200.00
82 12.00
8224.00
8236.00
8248.00
8260.00
8272.00
8284.00
8296.00
8308.00
8320.00
8332.00
8344.00
8356.00
8368.00
8380.00
8392.00
8404.00
7180.0
7 190.0
7200.0
72 10.0
7220.0
72 30.0
7240.0
72 50.0
7260.0
7270.0
7280.0
7290.0
73.00.0
73 10.0
7320.0
7330.0
7340.0
7350.0
7360.0
7370.0
7380.0
7390.0
7400.0
7410.0
7420.0
7430.0
7440.0
7450.0
7460.0
7470.0
7480.0
7490.0
7500.0
75 10.0
7520.0
7530.0
7540.0
7550.0
7560.0
7570.0
7580.0
7590.0
7600.0
76 10.0
7620.0
7630.0
7640.0
7650.0
7660.0
7670.0
(Can't) .
Crystal Frequency
Carrier
Kilocycles
Frequency
Megacycles Receive
Trans.
1 38.24
1 38.42
1 38.60
1 38.78
1 38.96
1 39. 14
1 39.32
1 39.50
1 39.68
1 39.86
140.04
140.22
140.40
140.58
140.76
140.94
141.12
141.30
141.48
141.66
141.84
142.02
142.20
142.38
142.56
142.74
142.92
143. 10
143.28
143.46
143.64
143.82
144.00
144. 18
144.36
144.54
144.72
144.90
145.08
145.26
145.44
145.62
145.80
145.98
146. 16
146.34
146.52
146.70
146.88
147.06
84 16.00
8428.00
8440.00
8452.00
8464.00
8476.00
8488.00
8500.00
8512.00
8524.00
8002.50
80 1 3.75
802 5.00
8036.25
8047.50
8058.75
8070.00
808 1.25
8092.50
8 103.75
8 1 1 5.00
8 1 26.25
8 1 37.50
8 148.75
8160.00
8 1 7 1.25
8 182.50
8 193.75
8205.00
82 16.25
8227.50
8238.75
82 50.00
826 1.25
8272.50
8283.75
8295.00
8306.2 5
83 1 7.50
8328.75
8340.00
835 1.25
8362.50
8373.75
8385.00
8396.25
8407.50
84 18.75
8430.00
844 1 .2 5
7680.0
7690.0
7700.0
77 10.0
7720.0
7730.0
7740.0
7750.0
7760.0
7770.0
7780.0
7790.0
7800.0
78 10.0
7820.0
7830.0
7840.0
7850.0
7860.0
7870.0
7880.0
7890.0
7900.0
79 10.0
7920.0
7930.0
7940.0
7950.0
7960.0
7970.0
7980.0
7990.0
8000.0
80 10.0
8020.0
8030.0
8040.0
8050.0
8060.0
8070.0
8080.0
8090.0
8100.0
8 1 10.0
8 120.0
8 1 30.0
8140.0
8 150.0
8 1 60.0
8 1 70.0
Crystal Frequency
Carrier
Kilocycles
Frequency
Trans.
Megacycles Receive
147.24
147.42
147.60
147.78
147.96
148. 14
148.32
148.50
148.68
148.86
149.04
149.22
149.40
149.58
149.76
149.94
150. 12
1 50.30
1 50.48
1 50.66
1 50.84
1 5 1.02
1 5 1.20
1 5 1.38
1 5 1 .56
1 5 1 .74
1 5 1 .92
152. 10
1 52.28
152.46
152.64
152.82
1. 53.00
153. 18
1 5 3.36
1 53.54
1 53.72
1 53.90
154.08
1 54.26
1 54.44
154� 62
1 54.80
1 54.98
155. 16
' 1'55.34
1 55.52
155.70
1 55.88
8452.50
8463.75
8475.00
8486.25
8497.50
8008.24
80 18.82
8029.4 1
8040.00
8050.59
806 1 . 18
807 1.76
8082.35
8092.94
8 103.53
8 1 14. 12
8 1 24.7 1
8 1 35.29
8 145.88
8 1 56.47
8167.06
8 177.65
8188.24
8 198.82
8209.41
8220.00
8230.59
824 1.18
825 1 .76
8262.35
8272.94
8283.5 3
8294. 12
8304. 7 1
83 1 5.29
8325.88
8336.47
8347.06
8357.65
8368.24
8378.82
8389.4 1
8400.00
84 10.59
842 1 . 18
843 1 .76
8442.35
8452.94
8463.53
8 1 80.0
8190.0
8200.0
82 10.0
8220.0
8230.0
8240.0
8250.0
8260.0
8270.0
8280.0
8290.0
8300.0
83 10.0
8320.0
8330.0
8340.0
8350.0
8360.0
8370.0
8380.0
8390.0
8400.0
84 10.0
8420.0
8430.0
8440.0
8450.0
8460.0
8470.0
8480.0
8490.0
8500.0
85 10.0
8520.0
8530.0
8540.0
8550.0
8560.0
8570.0
8580.0
8590.0
8600.0
86 10.0
8620.0
8630.0
8640.0
8650.0
, 8660.0
AWS TYPE DESIGNATION :
1ST SIGN I F ICANT
FI GURE
S I LVER
I DENTI F I ES CAPAC ITOR
AS COMPLY I N G WITH
AWS AND COLOR CODE
paper-dielectric capacitors is in the fol­
The type designation of fixed molded
CN
lowing form :,
CN
=
10
A
Component designation..
pet-dielectric.
fixed
300
pa­
Case designation ; identifies type
10
and , physical dimensions.
A
Characteristic.
300
Capacitance in micromicrofarads.
NOTE : CapaQtance in micromicrofarads.
CHARACTERISTICS
Color
Significant
Figure
o .
Letter
Reference
Multiplier
Centigrade
Farenheit
Maximum
Capacitance
Reduction
+20 ° C to -40 ° C
-67 to + 185
10%
+60, -20
10%
+60, -20
, OPerating
Temperature Range
1
A
-55 to +85
1
10
B
-55 to +75
Red
2
100
Orange
3
1000
Yellow
4
Green
5
Black
Brown
Blue
6
Violet
7
Gray
8
White
9
-67 to + 167
»
z
0.
I
""
o
Vt
n
::l1li
0.
�
""
I
�
EXAMPLE : Upper left dot, silver ; upper center dot, orange ; upper
right dot, black ; lower left dot, black ; lower center
.
dot, silver ; lower right dot, brown.
A WS type designation CN 10 A 300
Capacitance : 300 micromicrofarads
0.
I
.....
Tolerance
in %
AWS COLOR CODE
FIXED MOLDED PAPE R ·
D lE LECTR I C CAPACITORS
:!! ,.l:
.
.. _
III 0
to
C
Figure 6 - 1 .
A WS Color Code-Fixed M o ulded Paper Dielectric Capa citors
!.. S
0.
::1
BLACK DOT
I DENTI F I ES AS
COM PLY I N G WITH AWS
AND COLOR CODE
0,
co
.!! 1D
'""
1ST S I G N I F I CAN T
F I GURE
C
CHARACTERISTIC
Temp. K
Letter
Parts / MilFigure of
Designation Merit
lion / Degree C
9
c:::
See table
II
"
B
C
Color
Black
Significant
Figure
0
Decimal
Multiplier
%
Characteristic
1
10
Red
2
100
Orange
3
1000
Yellow
4
E
Green
S
F
Blue
6
Violet
7
Gray
8
White
9
G
,
Gold
0. 1
Silver
0.0 1
Black
2%
C
D
S%
J
K
20%
M
I
See Table
E XAMPLE : Upper left dot, black ; upper center dot, green ; upper right dot, black ; lower left dot, black ;
lower center dot, black ; lower right dot, black.
AWS Type : CM 20 A OSO M
Capacitance : SO micromicrofarads.
AWS C O L O R C O D E-F I X E D M I CA-DI E L E C T R I C CAPAC I TO R S
Fig ure 6 - 2 .
;
,
o·
G
10%
�
a
B
Brown
o to -SO
0.02 S %
�
1100
.
;
A
1
O.OS%
TABLE I-CH ARACT E R I ST I CS.
1"00
Letter
Reference
0.2%
o to + SO
"
-.
Tolerance
0.5 %
o to + 100
"
E
F
G
1.100
,�.
100
800
700
."
."
."
/"
600
.500
.
IOO
V
�
.
..
/'
/
p..I' f
".
/
/
."
TA B L E I I-FI G U R E OF M E R IT.
�
ao ·
50
�o
(" ..... CITANtl
IN
0.02 S%
/
/
JOO
/
400 1011
TYPE DESIGNATION : AWS mica dielectric capacitors
are numbered by the following system :
M
CM
050
20
A
CM : Component designation, fixed mica dielectric
20 : Class designation, identifies particular type.
A:
Characteristic.
0 50 : Capacitance in micromicrofarads.
M : Capacitance tolerance.
A WS Col o r Code-Fixed M ic a Dielectric Capa citors
l>
Z
0,
-1=0.
o
'""
n
:;l1l:I
0�
-1=0.
,
�
Figure of merit or Q for capacitors of characteristics
other than A and for which current ratings are not listed,
when measured at 1 megacycle shall be not less than the
value given in this table. For capacitances larger than 5()O
micromicrofarads, the value of Q shall be larger than 1500.
---------- -----
:1
0,
<
� -
Not
specified
-200 to + 200
+ 200
-100 to + 100
"
D
NOTE : Capacitance in micromicrofarads.
Maximum
Capacitance
Drift
Not
Not
Not
specified spe.:;ified specified
A
6
Q.
.. -.
CD 0
(l2
1ST SIGNI FICANT
FIGURE
�
AWS TYPE DESIGNATION :
form :
i?=�
() J»
..
I I
I I
�
H
f'
25
CC
SL
100
G
CC Component designation, fixed ceramic-dielectric capacitors.
�
25
SL
I ,
::
�
' I
Style ; identifies size and shape.
First letter, temp. coefficient ; second letter, tolerance of temp. co-
!\
�
NOTE :
dielectric capacitors is in the following
""Ln pu �
��� [
==
Type designation of fixed ceramic-
2ND SIGN I FICANT
FIG' IRE
TEMPERATURE
CO-EFFICIENT
efficient.
�
100 Capacitance value in micromicrofarads.
G
1. Leads may be oxial or terminal.
Capacita,nce tolerance.
>
Z
2. Inner electrode at broad band end.
3. Capacitance in micromicrofarads.
4. Broad band and four narrow bands identifies as complying with AWS color code.
Color
Black
Significant
Figure
±Tolerance of Capacitance
Multiplier
Capacitors
Greater than 1 0
Letter Symb.
Tolerance in %
Capacitors of
10 or Smaller
Letter Symb.
Tolerance in %
0
1
Brown
1
10
1
( F)
-30
Red
2
100
2
( G)
-80
Orange
3
1000
Yellow
4
Green
5
Blue
6
20
(M)
2.0
( G)
0,
�
'"
n
:lit
0�
�
,
�
�1 50
-220
5
-330
(J)
-470
Violet
7
Gray
8
0.0 1
White
9
0. 1
-750
AWS Type CC
10
(K )
0.25
( C)
+ 30
1.0
( F)
-300 + 500
S L 100
G
Capacitance ; 100 micromicrofarads
,
..0
Parts I Million
Degrees C
0
EXAMPLE : Broad band, green ; 1st narrow band, brown ; 2nd narrow band, black ; 3rd narrow band, brown ;
4th narrow band, red.
AWS Type CC2 5SL 100 G
0-
Temp. Co-elf.
of Capacitance
Fig ure 6-3.
A WS Color Code-Fixed Ceramic Dieledric Capacitor!.
AWS COLOR C O D E
FIXED C E R AM I C D I ELECTRI C CAPACITORS
� '"
CD
!l
.. _.
CD 0
co
c
,
<
o- �
w -
AN 1 6-40S C R624-2
Secti o n V I I
T a b l e of R e p l a c e a b l e P a rts
SECTION VII
TABLE OF REPLACEABLE PARTS
The parts listed in this table do not constitute a complete electrical and mechanical
breakdown of the equipment. The table lists all electrical parts together with
such operative mechanical parts as are subj ect to loss or failure, with the excep­
tion of structural and minor parts such as standard bolts, screws, nuts, and the
like. In some instances individual detail parts of a sub-assembly may not be listed
as separate items, since replacement of such items is impractical.
Ordering of Spare Parts
Each Service using this list has established certain depots and service groups for
the storage and issue of spare parts to its organizations requiring them.
The
regulations of each Service should be studied to determine the method and source
for requisitioning spare parts. The information in this list, as to manufacturer's
or contractor's name, type, model, or drawing number, is not to be interpreted
as authorization to field agencies to attempt to purchase identical or comparable
spare parts directly from the manufacturer or a wholesale or retail store except
under emergency conditions as covered by existing regulations of the Service
concerned.
U.s. Army Personnel: This table is for information only and is not to be used
as a basis for requisitioning parts . Authorities for obtaining maintenance items
are as follows: 1. For using organizations: applicable Service publications of the
00-30 series of AAF Technical Orders. 2. For higher maintenance and supply
echelons: applicable Service publications of the 08- 5 5 series of AAF Technical
Orders.
-
7-0
RMA COLOR CODES
CAPACITORS (MMFD)
FIRST
SIGNI FICANT
SECOND
SIGNIFICANT
DECIMAL
FIGURE
FIGURE
MULTIPLIER
�i�
==::::I
==
5
NT
WORK I N G
COLOR
N U M ERAL
BLACK
BROWN
RED
ORANGE
YELLOW
GREEN
BLUE
VIOLET
GRAY
W H IT E
GOLD
SILVER
NO COLOR
°
1
2
3
4
5
6
7
8
9
-
�
VOLTS
1 00
200
300
400
500
600
700
800
900
1 000
2000
500
TOLERANCE
MULTIP L I E R
TOLERANCE
1
10
1 00
1 ,000
1 0,000
1 00,000
1 ,000,000
1 0,000,000
1 00,000,000
1 ,000,000,000
0.1
0.0 1
1 %
2%
3%
4%
5%
6%
7%
8%
9%
5%
10%
20 %
SIGNI FI CANT
TH IRD
SIGNI FICANT
FIGURE
SIGNI FICANT
B
C
2ND DIGIT
M U LTIPLIER
A
COLOR
1 ST DIGIT
S I LVER
GOLD
BLACK
B R OWN
RED
ORANGE
YELLOW
GREEN
BLUE .
P U R PLE
GRAY
W H ITE
0.01
0.1
1 .0
10
1 00
1 ,000
1 0,000
1 00,000
1 ,000,000
1 0,000,000
1 00,000,000
°
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
�
D - TOLERANCE CODE:
GOLD
=
5%
SILVER
D
A
=
10%
C
NO COLOR = 20 %
B
A
0I
a
n
,.,
0...,
....
I
...,
BAN D OR
OLD COLOR ARRANGEMENT
SECOND
FIRST
RESISTORS (OHMS)
FIGURE
FIGURE
A B C D
==�- - 7�
BODY COLOR
VOLTAGE
N EW COLOR ARRANGEMENT
DECIMAL
D.C. WORKING
TOLERANCE
MULTIPLIER
BODY
COLOR
(NEW
COLOR
AR RAN GEM ENT
ONLY)
INDICATES TYPE OF R E SISTOR, AS FOLLOWS:
B LACK - COMPOSITION, NON-INSULATE D
.....
•
TAN , OLIVE OR W H ITE - COMPOSITION, INSULATE D
DAR K BROWN - W I R E-WOUND, INSULATE D
CIt
CD
,.
o·
�
�
...,
'"
I
CIt
CD
"
-
TABLE OF REPLACEABLE PARTS
NOTE: Parts i n d i cated by a
ci"
#
:I
sign in col u m n 2 are not available
as spare parts a n d are listed for reference p urpo s es only.
MODEL: RADIO SET SCR-62 4 - A O R SCR-624 - B
Reference
Symbol
*100
Army Stock No.
Navy Stock No.
British Ref. No.
3D90 1O- 1 S
1 10C/2932
39K90 1O-46
101
�
MAJOR ASSEMBLY: RADIO TRANSMlnER 8C-6 2 5 -A A N D BC-62 5 -AM
NAME OF PART and DESCRIPTION
CAPACITOR: Fixed; 10 micromicrofarads ± S % ; SOO
volts DCW; zero temperature coefficient; ceramicon.
.
(Ref. symbol changed to 1 0 1 -2 on some models. )
or
CAPACITOR: Fixed; io micromicrofarads ± S % ; soo
volts D.CW; zero temperature coefficient; ceramicon.
(Ref. symbol changed to 10 1-2 on some models.)
CAPACITOR: Same as ref. 100. (Changed to ref. 1 0 1 - 1
i n later models.)
FUNCTION
Balancing. nrst harmonic am­
pliner plate
MFR. and DESIG.
or
A WS TYPE
CONT. or GOVT.
DWG. or SPEC. No.
Erie type NPOK
Bendix No. AL8l82- 1 3
Zenith No. 22G748
Centralab 9 3 1.004
Zenith No. 22G748
Oscillator feedback
101-1
CAPACITOR: Same as ref. 10 1 .
Oscillator feedback
10 1-2
CAPACITOR: Same as ref. 100. (Not used on all transmitters.)
Balancing. nrst harmonic ampliner plate
l>
Z
0I
102- 1
3DKA4.700-S
3DKA6.800-7
3DKA6.800-8
3DKA6.800-9
3DKA6.800- 1 O
3DKA6.800- 1 1
3DKA6.800- 12
CAPACITOR: Fix«I; 4700 micromicrofarads
volts DCW; ceramic
or
CAPACITOR: Fixed; 6800 micromicrofarads
volts DCW mica
or
CAPACITOR: Fixed; 6800 micromicrofarads
volts DCW; paper
or
CAPACITOR: Fixed; 6800 micromicrofarads
volts DCW; mica.
± 20% ; 400
Meter Co. type DSBK 1200
Bendix No. C60288-472
Bendix No. A 102967-8
Zenith No. 22GS49
± 20 % ; 300
Aerovox type 1467
Cornell-Dubilier type
1WL
Micamold type 339
± 2 0 % ; 300
Solar type M. W.
Bendix No. C60290-682
Micamold type 336
Bendix No. C602 SS-682
Meter Co. type
DB-K 1200
Bendix No. C60287-682
Meter Co. type
DB-K 1200
Bendix No. C60288-682
± 20 % ; 300
CAPACITOR: Fixed; 6800 micromicrofarads ± 20 % ; 300
volts DCW; paper; oil impregnated.
or
CAPACITOR: Fixed; 6800 micromicrofarads ± 20% ; SOO
volts DCW; ceramic
or
CAPACITOR: Fixed; 6800 micromicrofarads ± 20 % ; 400
volts DCW; ceramic
or
"'Reference symbol 100 not used in some transmitters.
Oscillating screen coupling
�
CIt
Bendix No. C602 S-682
n
,.
0-
...,
�
I
3DKA6.800- 1 3
3DKA6.800- 1 4
3DA6-23
1 10C/ 2994
3DA lO-87
Micamold type 340
Bendix No. A180 1 5-682
6800 micromicrofarads + 30 0/0 ;
Dew; paper
Micamold type 336
Zenith No. 22G79 1
6000 micromicrofarads ± 200/0 ; 300
Aerovox type 1467
Comell·Dubilier type
1WL-3D6
Micamold type W
Electromotive Co. type
502L
Comell·Dubilier type
1WL
Bendix No. A102967-7
CAPACITOR: Fixed; 10,000 micromicrofarads ± 50/0 300
volts DCW; mica.
CAPACITOR: Same as ref. 102- 1 .
CAPACITOR: Same as ref. 102- 1 .
102-4
CAPACITOR: Same as ref. 102- 1 .
· 102-5
CAPACITOR: Same as ref. 102- 1 .
102-6
CAPACITOR: Same as ref. 102- 1.
102-7
CAPACITOR: Same as ref. 102- 1.
102-8
CAPACITOR: Same as ref. 102- 1.
102-9
CAPACITOR: Same as ref. 102- 1 .
102- 10
CAPACITOR: Same as ref. 102- 1 .
CAPACITOR: Same a s ref. 102- 1.
CAPACITOR: Same a s ref. 102- 1 .
CAPACITOR: Same as ref. 102- 1 .
CAPACITOR: Same a s ref. 102- 1 .
CAPACITOR: Fixed; 50 micromicrofarads ± 1 0/0 ; 500
volts DCW; silver mica
or
CAPACITOR: Fixed ; 50 micromicrofarads ± 100/0 ; 500
volts DCW; mica.
CAPACITOR: Fixed; 100 micromicrofarads ± 100 0/0 ; 500
volts DCW; zero temperature coefficient; ceramicon.
Second harmonic amplifier fila·
ment bypass
Meter shunt bypass
Power amplifier grid bypass
Power amplifier grid bypass
Bridge blocking
Bridge blocking
Oscillator cathode bypass
CAPACITOR: Fixed ; 1000 micromicrofarads ± 100/0 ; 300
volts DCW; mica.
CAPACITOR: 'same as ref. 102- 1 .
3D9050-40
1 10C / 2936
104
3D9 100-5 1
105 - 1
1 l0C/ 3026
3DA 1- 5 5
1 10C / 2 5
I
Co)
6800 mi�romicrofarads ± 100/0 ; 400
102-2
102-3
102- 1 1
102- 1 2
102- 1 3
102 - 1 4
102 - 1 5
103
.....
CAPACITOR: Fixed;
volts Dew; paper
or
CAPACITOR: Fixed ;
- 20% ; 400 volts
or
CAPACITOR: Fixed;
volts Dew; mica
or
Bendix No. A 1 02967- 1
Oscillator plate bypass
First harmonic amplifier grid
bypass
First harmonic amplifier fila·
ment bypass
First harmonic amplifier screen
bypass
First harmonic amplifier cath·
ode bypass
First harmonic amplifier plate
bypass
Second harmonic amplifier grid
bypass
Second harmonic amplifier grid
bypass
»
Z
... ;
0- :
I
8
'"
n
;l1l:I
0..,
...
I
..,
Erie type MIJ
Bendix No. A18253- 1
Zenith No. 22G7 5 1
F. W. Sickles
Bendix No. C563 1 5-500
First harmonic amplifier grid
coupling
Erie type NPOD
Muter Co.
Bendix No. A104485- 1
Zenith No. 22G740
Power amplifier filament bypass
Aerovox type 1468
Cornell·Dubilier type
5WL
Micamold type OXM
Electromotive type
50 3M
Bendix No. C564 1 5- 102
Zenith No. 22G745
CD
:=
0
'"
"
:I
�
TABLE OF REPLACEABLE PARTS
';"
"'"
MODEL: RADIO SET SCR·624·A OR SCR·62 4 · B
Reference
Symbol
Army Stock No.
Navy Stock No.
British Ref. No.
lOS-3
lOS-4
106
3DA2-63
107- 1
1 10C/2944
3DA 100- 124
1 08-2
1 10/C43
3DKA l- 109
1 10C / 2992
NAME O F PART and DESCRIPTION
CAPACITOR: Same as ref. lOS- 1.
CAPACITOR: Same as ref. 105- 1 . (Not used on all
transmitters. )
CAPACITOR: Fixed; 2000 micromicrofarads ± S % ;
800 volts DCW; mica. (Not used on all transmitters.)
CAPACITOR: Fixed; 100,000 micromicrofarads ± 1 0 % ;
400 volts DCW; paper.
CAPACITOR: Fixed; 1000 micromicrofarads ± 5 0/0 ; SOO
volts DCW; mica.
FUNCTION
Cornell·Dubilier type
1WPLS
Bendix No. A 182SS· 1
Speech amplifier screen bypass
Micamold type 345-2 1
Bendix No. A 1 80 1 5- 104
Zenith No. 22G746
Tone feedback
Cornell·Dubilier type
1W·S0 1
Micamold type WXM
Aerovox type 1467
Muter Co. Erie type
NPOL
Bendix No. A 102967-2
Zenith No. 22G742
Bendix No. A18 182- 16
Zenith No. 22G749
»
z
Centralab type 93 1-005
Zenith No. 22G749
I
"'"
o
VI
CAPACITOR: Same a s ref. 1 09- 1 .
Second harmonic amplifier grid
coupling
1 09-4
CAPACITOR: Same a s ref. 1 09- 1 .
Second harmonic amplifier grid
coupling
CAPACITOR: Same a s ref. 109- 1 .
High frequency bypass
CAPACITOR: Fixed ; 1 microfarad + 200/0 - 1 5 % ; 100
volts DCW; oil paper
or
Speech amplifier cathode bypass
3DK9020· 19
1 09-S
1 10
3DB 1 .092
1 10C / 30 1 4
3DB 1 .092- 1
3DB 1 .092-2
111
3DA500-40
1 10C / 30 1 3
Power amplifier grid coupling
Power amplifier grid coupling
CAPACITOR: Fixed; 1 microfarad ± 1 5 % ; 100 volts
DCW; oil paper, in metal case
or
CAPACITOR: Fixed; 1 microfarad ± 10 % ; 100 volts
DCW; oil paper, in metal case.
CAPACITOR: Fixed; 500,000 micromicrofarads + 20 % ;
- 1 S o/c ; 400 volts DCW; oil paper, in metal case.
:S
CONT. or GOVT.
DWG. or SPEC. No.
Power amplifier bypass
1 09-3
1 l0C/ 2933
MFR. and DESIG.
or
AWS TYPE
Speech amplifier grid bypass
Meter shunt bypass
109-2
3D9020·S
o
�
MAJOR ASSEMBLY: RADIO TRANSMITTER BC·6 2 5 ·A AND BC·6 2 5 ·AM
CAPACITOR: Fixed ; 20 micromicrofarads ± 1 micro·
microfarad ; SOO volts DCW; zero temperature coef.
cient; ceramicon
or
CAPACITOR: Fixed; 20 micromicrofarads ± 1 micro·
microfarad; SOO volts DCW; negative temperature co·
efficient; ceramic.
CAPACITOR: Same as ref. 1 09- 1 .
1 09- 1
VI
C1)
n
�.
Modulator screen bypass
0-
n
::oa
0100)
I
100)
"'"
C� rnell.Dubilier type
DYR-6 100
Aerovox type 1 30
Micamold type 306
Bendix No. A 104092-2
Zenith No. 22G739
Cornell·Dubilier type
DY Aerovox
Bendix No. A104092-2
Cornell-Dubilier type
DYR
Bendix No. A 104092-2
Cornell·Dubilier type
DYR-60S0
Aerovox type 430
Sprague type P6748
Micamold type 306
Bendix No. A 1 04092- 1
Zenith No. 22G738
1 13
3D9300- 1
1 10 C / 2993
1 14
3D9077VE5
I lOC/2983
1 15
3D9027V- l
1 l0C / 2984
1 16
3D90 16E5
I l OC / 2982
1 17
3D90 1 1
1 l0 C / 2 98 1
1 18
2C652 5A / 56
1 19
1 l 0C / 2958
2C652 5 A / s 7
121
2 C65 2 5A / J8
1 l0 C / 2960
3 C 1 074-24
122
1 l 0C / 296 1
2C652 5Aj J lO. 1
120
1 l 0C / 3225
1 2 3- 1
2Z7228.4
I l OH/924
123-2
125
'4
I
VI
2Z7298-2
1 l0C/ 3024
2Z7273-36
CAPACITOR: Fixed ; 300 micromicrofarads ± 5 % ; 500
volts DCW; mica
or
CAPACITOR: Fixed ; 300 micromicrofarads ± 5 0/e ; 500
volts DCW; mica.
CAPACITOR: Variable; 1 1 micromicrofarads minimum
to 65.6 micromicrofarads maximum ± 1 . 5 micromicro­
farads; 8 stators ; 5 rotors.
Speech amplifier plate blocking
Oscillator plate tuning
CAPACITOR: Variable; 3.5 micromicrofarads mlfl1mUm
to 27 micromicrofarads maximum ± 1 micromicro­
farad ; 12 stators ; 7 rotors.
First harmonic amplifier plate
tuning
CAPACITOR: Variable; 3 micromicrofarads minimum to
16.5 micromicrofarads maximum ± 1 micromicro­
farad ; 8 stators ; 5 rotors.
Second harmonic amplifier
plate tuning
CAPACITOR: Variable; 2.8 micromicrofarad minimum
to 1 1 micromicrofarads maximum ± 10 % ; 6 stators ;
3 rotors.
Power amplifier plate tuning
Aerovox type 1468
Cornell-Dubilier type
5Wl
Micamold type OXM
Aerovox type 1467L8
Bendix No. C563 14-30 1
Zenith No. 22G773
General instrument
special
Radio Condenser
special
General Instrument
special
Radio Condenser
special
General Instrument
special
Radio Condenser
special
General Instrument
special
Radio Condenser
special
Bendix
Bendix No. L72950
AL74 1 16- 1
Zenith No. SG2367
Bendix No. A 1 02967-3
Bendix No. L7295 '1
AL74 11 7- 1
Zenith No. SG2368
Bendix No. L72949
AL74 1 1 5- 1
Zenith No. SG2 366
Bendix No. L72948
AL74 1 1 4- 1
Zenith No. SG2365
COIL-R. F.: 9- 1 / 2 turns of No. 24 enameled copper wire
on ground coil from 1" long x 7 / 8" dia.
Oscillator plate tuning
COIL-R.F.: 15 turns No. 10 bare copper wire tapped at
8 turns; 5 / 8 " dia. x 1-7/8" long.
First harmonic amplifier plate
tuning
Bendix
Bendix No. AC57999- 1
Zenith No. SG2 2 3 5
COIL-R.F . : No. 10 silver plated S. D. copper wire dis­
tributed inductance line; approximately "U" shaped.
COIL-R.F.: 2 turns, gap, 2 turns of No. 10 S. D. silver
plated wire, center tapped at gap; 1 - 1 1 / 32 " long
3 / 4" dia.
COIL ASSEMBLY-ANTENNA COUPLING: 3 turns
No. 10 S. D. silver plated copper wire; adjusting screw
provided to vary coupling; 2-3 /4" x 2- 1 /4" x 9 / 16"
or
Second harmonic amplifier
plate tuning
Bendix
Power amplifier plate tuning
Bendix
Bendix
Zenith
Bendix
Zenith
An tenna coupling
Bendix
Bendix No. AC59922 - 1
Zenith No. SG2 546
Bendix
Colonial No. 4929 1
Jones type P-408
Amalgamated Radio
Tel.
Bendix No. A 1 028 1 1
Zenith No. 58G62
International resistance
type CM
Bendix No. A I 04470-2
Zenith No. 63G658
Chicago Tel. Supply
type 35
Bendix No. A 1 0 5 3 1 7-2
COIL ASSEMBLY-ANTENNA COUPLING: L-shaped
antenna board assembly with jacks and adjusting knob;
supports and gears mounted ; consists of coil and block
assembly, spring washer, and retaining washer.
CONNECTOR: 8-contact; male; polarized.
CONNECTOR: Same as ref. 1 2 3- 1 .
POTENTIOMETER: 1 megohm ± 20% ; 1 / 2 watt; taper
"C"; carbon. (See Ref. 180 and 1 8 1 . )
or
POTENTIOMETER: 1 megohn ; 1 / 2 watt; carbon; taper
"C"; case 1 / 8" dia. x 1 3 / 32 " deep
or
Transmitter control circuit
Power input from rack
Audio gain control
Bendix No. AC5 7998- 1
Zenith No. SG2234
No.
No.
No.
No.
AC58 149- 1
SG2246
AC58 1 50- 1
SG22 1 5
»
z
0I
.jlo.
o
VI
n
:::Ill
01'0.)
.jlo.
I
1'0.)
VI
CD
...
=.
o
::::I
�
TABLE OF REPLACEABLE PARTS
';'"
0-
MODEL: RADIO SET SCR-624 -A OR SCR-624 -B
Reference
Symbol
Army Slock No.
Navy Slock No.
Brilish Ref. No.
2Z7273-35
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NAME OF PART and DESCRIPTION
FUNCTION
POTENTIOMETER: 1 megohm; 1/2 watt; carbon; taper .
"C" ; case 1 - 1 /4" dia. x 1/2" deep.
MFR. and DESIG.
or
AWS TYPE
Bendix No. A 1 l47 1 7
Speech amplifier plate
Acme type T-3794
Dinion type ' SC3034
Bendix No. A I03034
Zenith No. 95C3 1
COIL-R.F.: Choke; 9.19 ohms doc; single layer wound
on steatite core 1 / 4" dia. x 1-3 / 4" long.
Second harmonic amplifier grid
choke
Ohomite type ZoO
Presto Electric
Utah Radio
Scientific Industry
type B- 1450 or
U. S. Rubber type
L- 100
Bendix No. A I 04090
Zenith No. 20039
127-2
COIL-R.F.: Same as ref. 127- 1 .
127-3
127-4
1 28- 1
COIL-R.F.: Same a s ref. 127- 1 .
COIL-R.F.: Same as ref. 127- 1 .
COIL-R.F.: Choke, 50 ohm doc resistance; 2 " long x
1 /2 " dia.
Second harmonic amplifier grid
choke
Power amplifier grid choke
Power amplifier grid choke
Oscillator grid choke
3C336- 19
127- 1
1 l0C / 3009
3C336- 1 1
1 l 0C / 30 1 2
3C326- 100
1 l0C/ 2895
128-2
128-3
1 30
2Z7650.3
1 l0F/489
131
2Z765-B6 106
132- 1
1 l 0F/490
3Z662 5-6
1 l0C/ 1673
3Z6625-37
1 32-2
1 3 3- 1
3Z6625-38
3Z6640- 1 3
1 10C/ 2926
COIL-A.F.: Reactor; 5000 ohms doc resistance; can size
1-7/ 16" x 1-7 /8" :it 2- 1 /4".
COIL-R.F.: Choke; 2.5 microhenries ; pie wound 2 - 1 /8"
long x 3- 1 / 8" dia.
COIL-R.F.: Same as ref. 128- 1 .
COIL-R.F.: Same a s ref. 128- 1 .
RELAY: Single pole double throw; 12 volts doc; 200
ohms doc resistance coil; 2 mounting holes; over­
all 2- 1 / 8" x 2- 1 / 2 " x 1 - 1 /4". (Relay 1 30 deleted in
Radio Transmitter BC-625-AM.)
RELAY: Double pole single throw; 12 volts doc; 200
ohms doc resistance coil; 2 mounting holes; over­
all 2- 1 / 8" x 2- 1 / 2 " x 1 - 1 /4".
RESISTOR: Fixed ; 25,000 ohms ± 5 0/0 ; 1 watt; carbon
or
Oscillator grid choke
Oscillator cathode choke
Power amplifier plate choke
Slow release relay
Contactor relay
Second harmonic amplifier grid
bias
RESISTOR: Fixed ; 25,000 ohms ± 100/0 ; l/i watt; carbon
or
RESISTOR: Fixed; 2 5,000 ohms ± 10% ; 1 watt; carbon.
RESISTOR: Same as ref. 1 32-1.
RESISTOR: Fixed ; 40,000 ohms ± 5 0/0 ; 1 watt; carbon
or
Second harmonic amplifier grid
bias
Power amplifier screen
dropping
�
CONT. or GOVT.
DWG. or SPEC. No.
International Resistance
type CM
1 26
=:
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MAJOR ASSEMBLY: RADIO TRANSMITTER BC-62 5 -A A N D BC-62 5 - AM
>
Z
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National type R100
Guthman type 5 0 1 2
Sickles type 1 380
James Millon type
34 103
Bendix No. A 10556
Zenith No. 20G28
Bendix No. A 1 l 33-32
Clare Co. type B-6 106
Cook Electric type
6 12- 100
Bendix No. A18258
Zenith No. 195G44
Clare Co. type B-6 106
�ook Electric type
6 1 2- 100
Erie type 505
Allen-Bradley type EB
Speer type SI- l
Erie type 504
Bendix No. A 18259
Zenith No. 195G43
Bendix No. A18004-253
Zenith No. 63G675
Bendix No. A 1 8 1 5 1-253
Erie type 505
Bendix No. A 1 8 1 50-2 53
Erie type 5 18
Allen Bradley type EB
Bendix No. A 1 8 1 58-403
Zenith No. 63G68 1
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3Z6640-3 1
RESISTOR: Fixed ; 40,000 ohms ± 107< ; 1 watt; carbon.
1 33-2
RESISTOR: Same as ref. 1 33 - 1 .
1 33-3
1 33-4
1 34
3Z599 1-5
1 35- 1
1 l0C/ 293S
3Z5976
RESISTOR: Same as ref. 1 33- 1.
RESISTOR: Same as ref. 1 33- 1 .
RESISTOR: Fixed; 1.53 ohms ± 1 'I< ; 1 / 2 watt; wirewound.
1 l0C/ 2937
1 35-2
1 36- 1
RESISTOR: Same as ref. 1 35 - 1 .
3ZK6400-36
3Z6400-2S
1 36-2
1 3S-3
RESISTOR: Fixed ; 4000 ohms ± 5 '/c ; 1 watt; carbon.
or
RESISTOR: Fixed ; 4000 ohms ± 1 O '/c ; 1 watt; .carbon.
RESISTOR: Same as ref. 1 36- 1 .
3Z6S0 1-25
l 1OC / 1677
3Z6S0 1.47
140-2
RESISTOR: Fixed ; 0.76 ohms ± 1 '/c ; 1 / 2 watt; wirewound.
3Z6S0 1-22
3Z6750-25
1 l0C/ 167 1
3Z6750-39
140-3
RESISTOR: Fixed ; 1 megohm ± 5 '/c ; 1 watt; carbon
or
RESISTOR: Fixed; 1 megohm ± 10% ; 1 watt; carbon
or
RESISTOR: Fixed; 1 megohm ± 20% ; 1 watt; carbon.
RESISTOR: Fixed ; 500,000 ohms ± 5 % ; 1 watt; carbon
or
Erie type S IS
Power amplifier screen
dropping
Voltage divider
Voltage divider
First harmonic amplifier plate
meter shunt
Second harmonic amplifier
plate meter shunt
Power amplifier plate meter
shunt
First harmonic amplifier
cathode bias
First harmonic amplifier
cathode bias
Speech amplifier screen
dropping
Third i-f grid leak
Tone voltage divider
RESISTOR: Fixed; 50,000 ohms ± 10 % ; 1 watt; carbon.
Tone voltage divider
RESISTOR: Same as ref. 140-2.
RESISTOR: Fixed ; 1 megohm ± 5 % ; 1 / 2 watt; carbon.
Tone feedback coupling
141-2
RESISTOR: Same as ref. 1 4 1 - 1 .
Input bridge
141-3
RESISTOR: Same as ref. 141- 1 .
Input bridge
141-4
RESISTOR: Same as ref. 141- 1 .
Input bridge
141- 1
3Z6S0 1-3
Input bridge
! lOC / 122 1
.....
J
.....
142
3Z6500-6 1
1 10C/ 1 669
RESISTOR: Fixed ; 5000 ohms ± 5 % ; 1 watt; carbon
or
Bendix No. A l S2 54-2
Zenith No. 63G660
Shallcross type l S I
Bendix No. AlS2 54- 1
Zenith No. 63G659
Erie type 5 1S
Bendix No. A 1 S 1 5S-402
Zenith No. 63G7S0
Erie type 5 1 S
Bendix No. A 1 3907-402
Erie type 505
Allen-Bradley type GB
Speer type SI- l
Bendix No. A 1 S004- 105
Zenith No. 63G705
Speech amplifier grid bias
Erie type 505
Erie type 505
Allen-Bradley type GB
Speer type SI- 1
Erie type 505
Allen-Bradley type GB
Speer type SI- l
Erie, Speer, AllenBradley
Erie type 505
Allen-Bradley type GB
Speer type SI- l
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Speer type SI- l
RESISTOR: Same as ref. 140-2.
140-4
Shallcross type l S I
International resistance
Bendix No. AlS004-504
Zenith No. 63G674
Bendix No. A 1S00 1-105
Zenith No. 63G667
Bendix No. A 1 S004-502
Zenith No. 63G672
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TABLE OF REPLACEABLE PARTS
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MODEL: RADIO SET SCR-624-A OR SCR-62 4 - B
Referen"e
Symbol
Army Stod, No.
Navy Sto"k No.
British Ref. No.
3Z6500-62
143- 1
3Z6008B2
1 l0C / 293 1
143-2
144
3Z672 5- 1
1 l0C / 1675
3Z672 5-2 1
145
3Z66 1 5·27
1 l0C / 292 3
3Z66 1-49
146
3Z6560-30
FUNCTION
RESISTOR: Fixed; 5000 ohms ± 100/0 ; 1 watt; carbon.
RESISTOR: Same as ref. 143- 1 .
(Deleted on some
models.)
RESISTOR: Fixed ; 2 50,000 ohms ± 5 0/0 ; 1/2 watt;
carbon
or
RESISTOR: Fixed ; 250,000 ohms ± 1 0 0/0 ; 1 / 2 watt
carbon.
RESISTOR: Fixed ; 15,000 ohms ± 5 % ; 1 watt; carbon
or
RESISTOR: Fixed; 1 5,000 ohms ± 1 0 % ; 1 watt; carbon.
RESISTOR: Fixed ; 6000 ohms; ± 1 0 0/0 ; 1 watt; carbon.
MFR. and DESIG.
or
AWS TYPE
Speech amplifier filament
dropping
Speech amplifier filament
dropping
Speech amplifier plate load
Modulator bias bleeder
Erie type 5 18
Bendix No. A 1 8 1 58-820
Zenith No. 63G735
Erie type 504
Allen-Bradley type EB
Speer type SI- 1 /2
Allen-Bradley type
EB" 1 /2
Bendix No. A 1800 1-254
Zenith No. 63G668
Allen-Bradley type GB
Erie type 5 18
Bendix No. A 1 8 1 5 8- 1 5 3
Zenith No. 63G678
Modulator bias bleeder
Erie type 5 18
Transformer bias bleeder
Erie type 5 1 8
Bendix No. A 1 8 1 58-602
Zenith No. 63G684
Bendix No. A 1 8 1 58- 183
Zenith No. 63G679
Transformer bias bleeder
Erie type 5 18
148
Transformer bias bleeder
Power amplifier grid sh� t
1 50
1 l0C/ 2930
3Z6005-6
RESISTOR: Fixed ; 50 ohms ± 5 0/0 ; 1 watt; carbon
or
Erie type 5 18
Erie type 5 18
Allen-Bradley type GB
First harmonic amplifier grid
coupling
Erie type 505
Allen-Bradley type GB
Speer type SI- 1
Erie type 505
Speer type SI- 1
Bendix No. A18004-500
Zenith No. 63G676
Erie type 505
Allen-Bradley type GB
Speer type SI- 1
Erie type 505
Bendix No. A18004- 503
Zenith No. 63G673
151·1
3Z6650-38
1 1OC/ 1666
3Z6650-30
1 5 1-2
RESISTOR: Fixed ; 50 ohms ± 1 0 % ; 1 watt; carbon.
RESISTOR: Fixed ; 50,000 ohms ± 5 0/0 ; 1 watt; carbon.
_
First harmonic amplifier grid
coupling
Oscillator grid bias
RESISTOR: Fixed ; 50,000 ohms ± 1 0 0/0 ; 1 watt; carbon.
RESISTOR: Same as ref. 1 5 1- 1 .
s
Speer type SI- 1
RESISTOR: Fixed ; 1 8,000 ohms ± 5 0/0 ; 1 watt; .carbon
or
RESISTOR: Fixed; 18,000 ohms ± 1 0 0/0 ; 1 watt; carbon.
RESISTOR: Fixed; 75 ohms ± 5 0/0 ; 1 watt; carbon.
1 l0C/ 2902
3ZK6005-6 1
:J
CONT. or GO VT.
DWG. or SPEC. No.
1 l0C/2929
3Z66 1 8- 1 3
1l0C/2924
3RC3 1AE 183K
3Z6007E- 1 3
147
c)'
MAJOR ASSEMBLY: RADIO TRANSMlnER BC-62 5 -A AND BC-6 2 5 -AM
NAME OF PART and DESCRIPTION
RESISTOR: Fixed; 82 ohms ± 5 0/0 ; 1 watt; carbon. (This
resistor has been deleted from production models.)
'"
CD
,.
-
First harmonic amplifier grid
bias
Bendix No. A 1 8 1 58-750
Zenith No. 63G685
Be� dix No. A 18005-500
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1 52 - 1
3Z6650-39
1 l0C/ 2928
3Z6650-5 1
Speech amplifier cathode bias
RESISTOR:
RESISTOR:
RESISTOR:
(Replaced
ments.)
RESISTOR:
or
RESISTOR:
3Z6200-72
153-4
154- 1
3Z6500-62
Fixed; 2000 ohms ± 10% ; 1 watt; carbon.
RESISTOR: Same as ref. 1 53-3.
RESISTOR: Fixed; 5000 ohms ± 5 % ; 1 watt; carbon
or
3Z9827.27
Modulator screen dropping
Crystal selector, channel A
1 56B
1 l0 F / 493
SWITCH-ROTARY: Part of ref. 1 56A.
SWITCH-ROTARY: Part of ref. 1 56A.
SWITCH-ROTARY: Part of ref. 1 56A.
SWITCH-ROTARY: 6 position; 1 pole; 2 deck; switch
travel stop; non-shorting rotor contacts.
Crystal selector, channel B
Crystal selector, channel C
Crystal selector, channel D
Meter switch
TRANSFORMER-A. F.: Microphone; center tapped primary with 5.2 ohms doc resistance; secondary ,4000
ohms doc resistance; 5 soldered lugs on bottom.
Microphone transformer
TRANSFORMER-A. F.: Interstage; center tapped secondary primary 1050 ohms doc resistance; secondary 2750
ohms doc resistance.
Interstage transformer
TRANSFORMER-A. F.: Modulation; center tapped primary; primary 690 ohms doc resistance; secondary 170
ohms doc resistance.
Modulation transformer
RELAY: Single pole single throw; 200 ohms doc resistance coil; 2- 1 / 2 " x 1-3/4" x 1 - 1 /4".
"Press-To-Talk" control
1 l0 F / 492
2Z10000- 14
159
2Z10000- 16
1 l0K / 7 10
160
2Z 10000- 18
1 l0K/ 7 1 1
161
2Z7650-G.7
1 l0F/ 509
Bendix No. A 1 8 1 58-202
Zenith No. 63G680
Erie type 5 18
RESISTOR: Same as ref. 154- 1 .
SWITCH-ROTARY: 4 section; 2 pOSitiOn; 1 pole; roll
over type; no shaft; changed by shifter slides.
158
Erie type 5 18
Speech amplifier grid
First harmonic amplifier screen
dropping
1 54-2
1 56A
3Z982 5-38
Bendix No. A 1 8 1 58-503
Zenith No. 63G683
Erie type 5 1 8
RESISTOR: Fixed; 5000 ohms ± 1 0 % ; 1 watt; carbon.
1 56C
1 56D
157
Allen-Bradley type GB
Erie type 5 1 8
Erie type 5 18
Speech amplifier cathode bias
1 l0C/ 2927
3Z6500- 1 1 3
1 l0K/ 709
I
-0
Same as ref. 153- 1
1 52-3
152·4
1 5 3- 1
1 l0C/2925
Oscillator screen dropping
Same as ref. 152-1.
Same as. ref. 1 52- 1 .
Fixed; 2000 ohms ± 5 '70 ; 1 watt; carbon.
by ref. 1 36- 1 and 1 36-2 in some equip­
RESISTOR: Same as ref. 1 52-1.
3Z6200-34
Oscillator screen dropping
Second harmonic amplifier
screen dropping
'
Modulator bias divider
Modulator bias divider
First harmonic amplifier
cathode bias
1 52-2
1 5 3-3
�
RESISTOR: Fixed; 50,000 ohms ± 5 '70 ; 1 watt; carbon
or
RESISTOR: Fixed; 50,000 ohms ± 10% ; 1 watt; carbon.
First harmonic amplifier
screen dropping
Bendix No. A 1 8 1 58-502
Zenith No. 63G682
Erie type 5 18
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Oak special
Yaxley special
Bendix No. AC56534- 1
Zenith No. 85G72
Oak , type 10206-H2
23045-H2
Bendix No. C56333
Zenith No. 85G7 1
Acme type T379 1
Dinion Coil CO.
type SC30 14
Rola Co.
Acme type T3792
Dinion COil Co. type
SC30 16
Rola Co.
Acme type T3795
Dinion Coil Co. type
SC30 18
Kenyon special
Rola Co.
Bendix No. 1030 14
Zenith No. 95G32
Clare type G
Cook Electri c type
612-101
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Bendix No. A I0450 16
Zenith No. 95G33
Bendix No. A1030 18
Zenith. No. 95G34
Bendix No. A107 1 4 1
Zenith No. 195G50
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�
TABLE OF REPLACEABLE PARTS
';'l
...
°
162
Army Sto�k No.
Navy Sto�k No.
British Ref. No.
3C336-2 1
1 l0C / 30 1 7
162- 1
1 62-2
163
2C6525A/T2
1 64- 1
1 l0M / 2 327
2C6525A/T2 / 1
1 l0M / 2 322
NAME OF PART and DESCRIPTION
FUNCTION
COIL-R.F. CHOKE: Single layer of 38 turns No. 28
enameled wire; wound on a 1 megohn ± 20 % , 1/2
watt resistor or on a specially molded form. (Replaced
by ref. 162 - 1 in some equipments.)
COIL-R.F. CHOKE: . Same as ref. 162. (Deleted in some
equipments.)
COIL-R.F. CHOKE : Same as ref. 1 62. (Not in some
equipments. )
CLAMP-TUBE ASSEMBLY: Consists of 5 / 8" L-shaped
spring clamp fastened to micalex trip 1 / 2 " wide x 3 "
long x 5/8" high, with screw and nut.
BOARD-CLAMP: Micalex strip 2-3/8" x 1 / 2 " x 1 18" ;
part of ref. 163.
Speech amplifier cathode r-f
choke
MFR. and DESIG.
or
AWS TYPE
Bendix
Bendix No. A 1 0430 1· 1
Zenith No. SG2300
For second harmonic amplifier
Bendix
Bendix No. AA 1 02860- 1
Zenith No. 83G323
Part of ref. 163
Bendix
Bendix No. A I02452
Zenith No. 83G32 3
Bendix No. A 1 l 357
Zenith No. 46G60
SHIFTER UNIT-FREQUENCY: Transmitter;
channel slides and tuning controls.
Transmitter channel selection
Weston type J- 10829
Chicago Die Mold
type 86G60
Bendix
Power amplifier shield.
Bendix
Bendix No. AC85%- 1
Zenith No. SG2547
Transmitter output
Bendix
Bendix No. AA I0295 1 - 1
Zenith No. SG2254
SOCKET-TUBE : 8-contact; octal; with retainer ring.
For Tube JAN-6G6G,
oscillator
Amphenol type S-S8TM Bendix No. A I 04087- 1
Zenith No. 78G72
Cinch . type 9894
1 69-2
SOCKET-TUBE: Same as ref. 169- 1 .
1 69-3
SOCKET-TUBE: Same as ref. 169- 1.
1 69-4
SOCKET-TUBE: Same as ref. 169- 1.
For Tube JAN- 12A6, first
harmonic amplifier
For Tube JAN- 12A6,
modulator
For Tube JAN- 12A6,
modulator
169-5
SOCKET-TUBE : Same as ref. 169- 1 . '
For Tube JAN-6SS7, speech
amplifier
SOCKET-TUBE: 7 contact; steatite; supplied with two
clip and lead assemblies.
For Tube JAN-832, second
harmonic amplifier
1 66
1 l0M / 1 880
2C6525A / F l
167
1 l0L.6
2C6525A / S l
1 l0M/2 3 1 8
168
2C6525A / S2
169- 1
1 l0H / 930
3Z8654.7
includes
SHIELD ASSEMBLY: Plate with partition on rear; Dzus
fasteners in each corner; plate 5-3 /4" x 5" x 1 / 16" ;
partition 3- 1 /4" x 2- 1 / 16" x 1 / 2 " ; at right angles to
plate.
CONNECTOR ASSEMBLY-FOR ANTENNA: 2-contact; 2- 1 /8" x 7 / 8" x 3/ 16" phenolic board.
1 l0H /935
1 70- 1
2Z8663- 1
1 l0H /940
�
Speech amplifier cathode r-f
choke
Filament circuit r-f choke
Part of ref. 163
Meter switch
2Z5799
:I
CONT. or GO VT.
DWG. or SPEC. No.
BOARD-CLAMP: Same as ref. 164- 1.
KNOB-BAR: Black bakelite; pointer line filled with
�ite enamel.
164-2
165
o·
MAJOR ASSEMBLY: RADIO TRANSMITTER BC -62 5 -A AND BC-6 2 5 -AM
MODEL: RADIO SET SCR-62 4 - A OR SCR-624 -B
Referen�e
Symbol
lit
CD
n
-
Johnson type 247
Ucinite
Bendix No. AC5799 1 - 1
Zenith No. SG223 1
Bendix No. A3 1778
Zenith No. 78G 7 1
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SOCKET-TUBE: Same as ref. 170- 1 .
1 70-2
171
2C652 5A/S3
1 72
1 l0H/93 1
2Z72 53
1 l0A/433
173- 1
6L6S32-2SRE
1 l0M / 2324
173-2
173-3
173-4
1 74
6LK5033-2
175- 1
1 l0M/ 239 1
2S522A / C2
SCREW-MOUNTING: Same
SCREW-MOUNTING: Same
SCREW-MOUNTING: Same
SCREW-THUMB: Head 1 / 2 "
knurled brass.
as ref.
as ref.
as ref.
dia. x
173- 1.
1 73- 1.
1 73- 1 .
1 /4" deep; diamond
1 75-2
1 75-3
COLLAR-COUPLING ASSEMBLY: Same a s ref. 175- 1 .
1 76-2
COLLAR-COUPLING ASSEMBLY: Consists o f coup­
ling arm, coupling collar, coupling spring, and cad­
mium plated steel setscrews; over-all l- 1 / S" x 7/S" x
7 / 16".
COLLAR-COUPLING ASSEMBLY: Same as ref. 1 76- 1.
1 76-3
COLLAR-COUPLING ASSEMBLY: Same as ref. 1 76- 1.
1 76- 1
2S522A/C3
1 l0M / 2 573
177
2ZK3303
1 l0M/2574
lS0
lSl
I
BOARD ASSEMBLY-CRYSTAL: Consists of crystal
board ; 50,000 ohm ± 5 0/0 ; 1 / 2 watt resistor; r-f re­
actor, 50 ohms doc resistance; dimensions, 4- 1/8" x
1- 1 1 / 16" x 3/ 16" with spacer mountings 1 l / 16" long.
SCREW-MOUNTING: Cold-drawn steel; cadmium
plated ; 1-3 /4" long over-all; painted red.
COLLAR-COUPLING ASSEMBLY: Consists of coupling
stub, coupling collar, and coupling arm; over-all 1" x
3 / 4" x 1 1 2 " . ..
COLLAR�COUPLING ASSEMBLY: Same as ref. 1 7 5- 1 .
1 l0M / 2572
.....
CONNECTOR-PLUG BOARD ASSEMBLY: 2-contact;
male ; 1 / 2 " x l / S" contact plugs.
COUPLING AND SHAFT ASSEMBLY: Consists of 2
flexible shaft couplers joined together by a 2-3/4" x
5 / 16" dia. insulated shaft; over-all length 7- 1 /4".
RESISTOR: Same as ref. 251 (Resistors lS0 and lSl
replace ref. 125 in some equipments.)
RESISTOR: Same as ref. 262 - 1 . (Resistors lS0 and l S l
replace ref. 125 i n some equipments.)
WASHER "C" ; 0.250" outside diameter x 0 . 1 2 5 " inside
diameter x 0.032" thick; 60-degree section cut out.
For Tube }AN-S32, power
amplifier
D-C meter socket
Bendix
Bendix No. AA 1029$4- 1
Zenith No. SG2252
For crystals
Bendix:
Bendix No. AC5S2 1 3- 1
Zenith No. SG2242
Mounting transmitter to rack
Bendix special
Armstrong Crown
Screw, Guthrie
Bendix No. A102735
Zenith No. 97G 1 4 1
Bendix
Bendix No. A102469
Zenith No. 1 12G622
Bendix
Bendix No. AA106 124- 1
Zenith No. SG2 2 1 6
Mounting transmitter
Mounting transmitter
Mounting transmitter
For second harmonic
tube clamp
to rack
to rack
to rack
amplifier
Capacitor side of oscillator
tuning control
Capacitor side of first harmonic
amplifier tuning control
Capacitor side of power
amplifie�uning control
Shifter side of oscillator. tuning
control
Shifter side of oscillator tuning
confier tuning control
Shifter side of power amplifier
tuning control
Second harmonic amplifier
tuning
0I
Bendix
Bendix N o . AA 106 125-1
Zenith No. SG2205
Bendix
Bendix No. AC5S647- 1
Zenith No. SG2224
Bendix
Bendix No. A102 179
Zenith No. lSSG 3 1
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Audio gain
Audio gain
lS7
6LK77004
VT- l 1S
2T l lS
2}S32
TUBE }AN-832 : Push-pull r-f beam power amplifier;
type S32.
Second harmonic amplifier
1 l0 E / liH
2Tl lS
2}S32
1 l0E / 1S3
TUBE JAN-S32 : Push-pull r-f beam power amplifier;
type 832 .
Power amplifier
VT- l lS
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RCA
Kenrad
RCA
Kenrad
Q.
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CD
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TABLE OF REPLACEABLE PARTS
i'l
...
�
Army Stock No.
Navy Stock No.
British Ref. No.
VT. 1 34
2T 1 34
2J 12A6
VT· 1 34
2T 1 34
2J 12A6
VT. 1 34
2T 1 34
2J 12A6
VT. 198·A 2T198A
2J6G6G
VT. 199
2T199
2J6SS7
VT. 199
2T199
2J6SS7
NAME OF PART and DESCRIPTION
3D90 10· 1 9
1 l0C/ 2964
3DK90 1O·45
202· 1
3DK9680·5
TUBE JAN· 12A6: Beam power amplifier; type 12A6.
First harmonic amplifier
TUBE JAN· 12A6: Beam power amplifier; type 12A6.
Modulator
TUBE JAN· 12A6: Beam power amplifier; type 12A6.
Modulator
ruBE JAN·6G6G: Power amplifier pentode; type 6G6G.
Oscillator
TUBE JAN·6SS7: Triple-grid, super·control amplifier;
type 6SS7.
,
TUBE JAN·6SS7 : Triple-grid, super.control amplifier;
type 6SS7. (This tube deleted on later models of trans·
mitter.)
Speech amplifier
1 l0C/2966
3DK9680·6
3DK9680·7
202·2
202·3
202·4
202-5
202·6
202·7
202·8
202·9
CAPACITOR: Fixed; 10 micromicrofarads ± 20% ; 500
volts DCW; mica.
or
CAPACITOR: Fixed ; 1 0 micromicrofarads ± 20% ; 500
volts DCW; negative temperature coefficient; ceramic.
CAPACITOR: Fixed; 680 micromicrofarads ±
volts DCW; mica
or
MFR. and DESIG.
or
AWS TYPE
FUNCTION
MODEL: RADIO SET SC R-624-A AND SCR-624 - B
20 1
Same
Same
Same
Same
Same
Same
Same
Same
as
as
as
as
as
as
as
as
ref.
ref.
ref.
ref.
ref.
ref.
ref.
ref.
202· 1 .
202- 1 .
202· 1 .
202- 1 .
202· 1 .
202· 1 .
202· 1 .
202· 1 .
::I
20% ;
R·F indicator diode
MAJOR ASSEMBLY:
RADIO RECEIVER BC-624-A A N D BC-624 -AM
R ·F grid cl'f8pling
Aerovox type 1468
Micamold type OXM
Bendix No. C58469· 100
Zenith No. 22G76 1
R-F grid coupling
Erie type N7 50K
Bendix No. C60329· 100
R·F cathode bypass
Aerovox type 1468LST
Cornell·Dubilier type
5WLST
Micamold type OXM
Erie type NPOL
Bendix No. C58479·681
Zenith No. 22G760
22G543
Muter Co. type
BB·K 1200
R·F AVC filter
R·F screen bypass
R·F plate bypass to cathode
R·F plate bypass to ground
Mixer cathode bypass
Mixer screen bypass
Harmonic amplifier B+ filter
Harmonic amplifier plate
bypass to cathode
�
CONT. or GO VT.
DWG. or SPEC. No.
RCA
Kenrad
RCA
Kenrad
RCA
Kenrad
RCA
Kenrad
RCA
Kenrad
RCA
Kenrad
CAPACITOR: Fixed; 680 micromicrofarads ± 20 % ;
500 volts DCW; zero temperature coefficient ceramic
or
CAPACITOR: Fixed; 680 micromicrofarads ± 20 % ;
500 volts DCW; ceramic.
CAPACITOR:
CAPACITOR:
CAPACITOR:
CAPACITOR:
CAPACITOR:
CAPACITOR:
CAPACITOR:
CAPACITOR:
o·
"
..
MAJOR ASSEMBLY: RADIO TRANSMlnER BC-6 2 5 -A AND BC-6 2 5 -AM
MODEL: RADIO SET SCR-62 4 - A OR SCR-624 - B
Reference
Symbol
'"
CD
Bendix No. C60324·68 1
Bendix No. C60323·68 1
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Z
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202- 10.
CAPACITOR: Same as ref. 202- 1 .
202- 1 1
CAPACITOR: Same a s ref. 202- 1 .
202- 12
CAPACITOR: Same a s ref. 202· 1 .
202- 1 3
CAPACITOR: Same a s ref. 202· 1 .
202- 14
CAPACITOR: Same a s ref. 202- 1.
202- 1 5
CAPACITOR: Same as ref. 202· 1 .
202- 16
202- 17
202- 18
202 - 1 9
202-20
202-2 1
CAPACITOR:
CAPACITOR:
CAPACITOR:
CAPACITOR:
CAPACITOR:
CAPACITOR:
202-22
CAPACITOR: Same a s ref. 202- 1 .
202-2 3
CAPACITOR: Same a s ref. 202- 1 .
202-24
202-2 5
202-26
202-27
203- 1
CAPACITOR: Same a s ref. 202- 1 .
CAPACITOR: Same a s ref. 202· 1 .
CAPACITOR: Same a s ref. 202- 1 .
CAPACITOR: Same a s ref. 202· 1 .
CAPACITOR: Fixed ; 4 7 micromicrofarads ± 20 0/0 ; 500
volts DCW; mica
or
3DK9047-7
3DK9047- 1O.
3D9050-4 1
1 10C/ 3742
I
Co)
ref.
ref.
ref.
ref.
ref.
ref.
202- 1 .
202- 1 .
202· 1 .
202· 1.
202- 1 .
202· 1 .
Fixed ; 47 micromicrofarads ± 20 0/0 ; 500
negative temperature coefficient; ceramic
Fixed ; 50 micromicrofarads ± 200/0 ; 500
mica.
CAPACITOR: Same as ref. 203-1.
203-3
203-4
CAPACITOR: Same as ref. 203- 1 .
CAPACITOR: Same a s ref. 203· 1 .
3D90 1 5-8
1 10C / 2967
-
as
as
as
as
as
as
203-2
204
"I
CAPACITOR:
volts DCW;
or
CAPACITOR:
volts DCW;
Same
Same
Same
Same
Same
Same
3DK90 1 5-28
Harmonic amplifier plate
bypass to ground
Harmonic amplifier cathode
bypass
Harmonic amplifier screen
bypass
Harmonic generator plate
.bypas$
Harmonic generator plate
bypass
Harmonic generator cathode
bypass
R-F B+ filter
Audio B+ filter
R·F heater bypass
Mixer heater bypass
Mixer heater bypass
Harmonic amplifier heater
bypass
Harmonic amplifier heater
bypass
Harmonic generator heater
bypass
First i-f suppressor bypass
Second i·f suppressor bypass
Third i·£ suppressor bypass
Os cillator plate coil bypass
Mixer grid coupling
CAPACITOR: Fixed ; 15 micromicrofarads ± 200/0 ; 500
volts DCW; mica
or
CAPACITOR: Fixed ; 15 micromicrofarads ± 200/0 ; ·500
volts DCW; negative temperature coefficient; ceramic
»
z
Aerovox type 1468
Cornell-Dubilier type
5LS
Micamold type OXM
Erie type N7508
Bendix No. C58469-470
Zenith No. 22G759
0I
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n
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..
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Bendix No. C60329·470
Cornell-Dubilier type
5WLS
Bendix No. C·58469-500
Aerovox type 1468
Cornell-Dubilier type
5WLST
Micamold type OXM
Bendix No. C58469· 150
Zenith No. 22G757
Erie type N750K
Bendix No. C60329- 15Q
Harmonic amplifier grid
coupling
AVC diode coupling
First audio plate r·f bypass
Oscillator plate resonator
o·
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CD
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-
TABLE OF REPLACEABLE PARTS
MODEL: RADIO SET SCR-624-A A N D SCR- 6 2 4 - B
Reference
Symbol
205
Army Stock No.
Navy Stock No.
British Ref. No.
3DK9220·3
3D9250·27
1 l0C/ 3726
MAJOR ASSEMBLY:
NAME OF PART and DESCRIPTION
CAPACITOR:
volts DCW;
or
CAPACITOR:
volts DCW;
Fixed; 220 micromicrofarads ± 200/0 ; 500
mica
FUNCTION
Harmonic generator grid
Fixed ; 2 50 micromicrofarads ± 200/0 ; 500
mica.
206· 19
206·20
206·2 1
CAPACITOR: Same as ref. 102- 1 .
Third i - f heater bypass
2 06-22
CAPACITOR: Same as ref. 102- 1 .
Oscillator and audio squelch
heater bypass
206· 18
t206-23
207· 1
3D9060- 1
1 l0C/ 297 1
as ref.
as ref.
as ref.
as ref.
as ref.
as ref.
as ref.
as ref.
as ref.
as ref.
as ref.
as ref.
a s ref.
as ref.
a s ref.
a s ref.
as ref.
102· 1 .
102· 1 .
102· 1 .
102· 1 .
102· 1 .
102· 1 .
107· 1 .
102· 1 .
102· 1 .
102· 1 .
102· 1 .
102· 1 .
102- 1 .
102· 1 .
102- 1 .
102- 1 .
102- 1 . (Stock number 3DA6·
as "tef. 102· 1 . (Stock number 3DA6·
Second audio grid coupling
as ref. 102- 1 .
as ref. 102- 1 .
First i·f heater bypass
Second i-f heater bypass
CAPACITOR: Same as ref. 102- 1 .
Third i-E grid bypass
CAPACITOR: Fixed; 60 micromicrofarads ± 2 0/0 ; 500
volts DCW; silver mica.
Mixer plate resonator
Mixer plate resonator
tparts which are applicable to Radio Receiver BC-624-A, only.
Parts with
DO
MFR. and DESIG.
or
AWS TYPE
CONT. or GOVT.
DWG. or SPEC. No.
Aerovox type 1468
Micamold type OXM
Bendix No. C 58469·22
Zenith No. 22G758
Aerovox type 1468
Bendix No. C58469·25 1
Oscillator plate bypass
Oscillator cathode bypass
Mixer plate bypass
First i·f AVC filter
First i·f cathode bypass
First i·f screen bypass
First i · f plate bypass
Second i·f AV C filter
Second i·f cathode bypass
Second i·f screen bypass
Second i·f plate bypass
Third i-f cathode bypass
Third i·f screen bypass
Third i - f plate bypass
B + bypass
Audio squelch grid bypass
Audio coupling
CAPACITOR: Same
CAPACITOR: Same
CAPACITOR: Same
CAPACITOR: Same
CAPACITOR: Same
CAPACITOR: Same
CAPACITOR: Same
CAPACITOR: Same
CAPACITOR: Same
CAPACITOR: Same
CAPACITOR: Same
CAPACITOR: Same
CAPACITOR: Same
CAPACITOR: Same
CAPACITOR: Same
CAPACITOR: Same
CAPACITOR: Same
23 not included.)
CAPACITOR: Same
23 not included.)
CAPACITOR: Same
CAPACITOR: Same
206· 1
206·2
2 06,3
206·4
206·5
2 06·6
206·7
206·8
206·9
206· 10
206· 1 1
206· 12
206· 1 3
206- 14
206· 1 5
2 06-1 6
206· 17
o·
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:5:
RADIO RECEIVER BC-624 -A AND BC-624 -AM
,.
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Aerovox type 1469T
F. W. Sickles
Micamold type PO
Cornell· Dubilier
type 5R
Electromotive type 603
ideotification mark are applicable to both receivers.
Bendix No. C584950600
Zenith No. 22G754
207-2
207-3
207-4
207-5
207-6
207-7
207-S
20S- 1
3 D90 15-9
3D9100-56
309330-4
3DK9330·S
3 DAI OO· S9
llOC/161S
3DA 100-80
1 10C /161S
':'I
-
UI
·2 1 1- 1 B
· 2 1 l- 1C
Second i·f grid resonator
CAPACITOR:
Same as ref. 207- 1 .
Same as ref. 207- 1 .
Second i·f plate resonator
.
Third i·f grid resonator
CAPACITOR:
Same as ref. 207- 1 .
Third i·f plate resonator
CAPACITOR:
Same as ref. 207- 1 .
CAPACITOR: Fixed; 1 5 micromicrofarads
volts DCW; mica
or
Diode resonator
± 5 0/0 ; 500
�ixer plate resonator
CAPACITOR: Fixed; 15 micromicrofarads ± 5 % ; 500
volts Dew; negative temperature coefficient.
Second i·f plate resonator
Third i·f grid resonator
CAPACITOR: Same as ref .. 20S- I .
Third i·f plate resonator
Zenith No. 22G764
Aerovox type i46S
Comell·Dubilier
type 5WLST
�icamold type OX�
Bendix No. C5S469- 1 0 1
Zenith No. 22G762
Erie type N750L
Bendix No. C60329- 10 1
8
CIt
Aerovox type 146SI;ST
Comell·Dubilier
type 5WLST
�icamold type OX�
Bendix No. C5S469'33 1
Zenith No. 22G763
t
Diode resonator
± 20 % ; 500
CAPACITOR: Fixed; 100 micromicrofarads ± 200/0 ; 500
volts new; negative temperature coefficient; ceramic.
± 20% ; 500
Audio diode bypass
Audio diode bypass
CAPACITOR: Fixed; 330 micromicrofarads ± 2 0 % ; 500
volts Dew; zero temperature coefficient ceramic
or
CAPACITOR: Fixed; 330 micromicrofarads
volts Dew; ceramic.
Centralab type 932-00 1
First i·f plate resonator
CAPACITOR: Same as ref. 208- 1.
CAPACITOR: Fixed; 330 micromicrofarads
.'
. volts Dew; mica
or
Bendix No. A2 57 1 5 - 1 5
Zenith No. 22G764
Second i·f grid resonator
CAPACITOR: Same as ref. 20S- 1 .
CAPACITOR: Fixed ; 1 0 0 micromicrofarads
volts . Dew; mica
or
firie type N6S0K
First i·f grid resonator
CAPACITOR: Same a s ref. 20S- 1 .
3pK9330-7
t2 1 lC
·2 1 1- 1 A
Same as ref. 207- 1 .
CAPACITOR: Same as ref. 20S- 1 .
1 l0C/ 2969
f2 UB
First i·f plate resonator
CAPACITOR:
CAPACITOR: Same as ref. 20S- 1 .
3DK9 100- l lS
t2 1 1A
First i·f grid resonator
CAPACITOR: Same as ref. 20S- 1 .
1 l0C/2965
2 10
Same as ref. 207- 1 .
Same as ref. 207- 1 .
CAPACITOR:
1 l0C/2950
3DK90 1 5-29
208-2
20S-3
;Z08-4
20S-5
20S-6
20S-7
20S·S
t209
CAPACITOR:
CAPACITOR:
Erie type NPOK
± 20 % ; 500
CAPACITOR: Fixed; 3-section; 100,000 micromicrofar·
ads. per section + 20% .... 10% ; 400 volts Dew; oil
paper.
First audio cathode bypass
CAPACITO R: Part of 3 1 1A.
First audio screen bypass
CAPACITOR: Part of 3 HA.
AVC filter
CAPACITOR: Fixed; 3-section; 100,000 micromicrofar·
ads per section ± 1 5 % - 12 . % ; 400 volts Dew; oil
paper; special.
First audio cathode
CAPACITOR: Part of ref. 2 1 1-1A.
CAPACITOR: ' Part of ref. 2 1 1- 1A.
tParts which are applicable to Radio Receiver BC-624-A, only. Parts with
·Parts which are applicable to Radio Receiver BC624-AM only.
First audio screen
Aerovox type 30
Electrical Utilities
type 10722- 1
Comell·Dubilier
Bendix No. A25096
AVC filter
no
Bendix No . C60324-33 1
Bendix No. C60323-33 1
Aero
Solar
�a1lory
Electric Utilities
identification mark are . applicable to both receivers.
-
0I
�uter Co. type
BB·K 1200
•
Z
n
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AI06 175
Zenith No. 22G753
Bendix No. A25096
::
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�
TABLE OF REPLACEABLE PARTS
.....
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0.
MODEL: RADIO SET SCR-624-A A N D SCR-624-B
Reference
Symbol
*2 1 l-2A
*2 1 1-2B
*2 1 1-2C
2 12A
Army Stock No.
Navy Stock No.
British Ref. No.
3DB6-22
3DB 1O-2 5
1 l 0C / 2986
2 12B
2 12 C
2 12D
213
3DB 1 .484
2 14
3D9082
UOC / 3025
1 l0C/2972
2 16A
3D9036V
110C/ 2980
NAME OF PART and DESCRIPTION
CAPACITOR: Same as ref. 2 11- 1A.
CAPACITOR: Same as ref. 2 1 1- 1A.
CAPACITOR: Same as ref. 2 1 � 1A.
CAPACITOR: Fixed; 4-section; section A, 1 microfarad
+ 100 % - 10 % ; 400 volts DCW; section B, 6 micro­
farads + 100 % - 10% ; 400 volts DCW; section C,
1 microfarad + 100% - 10 % ; 50 volts Dew ; section
D, 2 microfarads + 100 % - 10 % ; 50 volts Dew; oil
filled p,aper; over-all 3-7 / 8 " x 2-5 /8" x 2-5 / 16"
or
CAPACITOR: Fixed ; 4-section; one section 10 micro­
farads :t 10 % ; 350 volts DCW; one section 20 micro­
farads :t 1 0 % ; 2 50 volts Dew; two sections 5 micro­
farads :t 1 0 % ; 1 5 0 volts Dew; electrolytic; 4 color
coded solder lugs on bottom for positive leads, case
common negative.
CAPACITOR: Part of ref. 2 12A.
CAPACITOR: Part of ref. 2 12A.
CAPACITOR: Part of ref. 2 12A.
CAPACITOR: Fixed; 1 microfarad :t 10 % ; 100 volts
DCW; oil paper; metal case; mounting brackets on
each end.
CAPACITOR: Fixed ; 82 micromicrofarads :t 2 % ; 500
volts DCW; silver mica.
CAPACITOR: Variable; with trimmer; 3-section; each
section 6 micromicrofarads minimum to 36 micro microfarads maximum; 10 stator plates; 11 rotor plates; common shaft.
MAJOR ASSEMBLY:
Audio B+ filter
Audio cathode bypass
Second audio cathode bypass
R-F and mixer heater bypass
Aerovox type 1469
Micamold type PO
Cornell-Dubilier
type 5R
Bendix No. C58495-820
Zenith No. 22G7 5 5
R-F grid tuning
Bendix
Bendix No. L72799- 1
Bendix
Bendix No. L72798- 1
CAPACITOR: Variable; with trimmer; 2-section; sec­
tion 1, 6.5 micromicrofarads minimum to 39.6 micro­
farads maximum; 1 1 stator plates ; 12 rotor plates;
section 2, · 6 micromicrofarads minimum to 36 micro­
farads maximum ; 10 stator plates, 1 1 rotor plates;
ganged on common shaft.
Harmonic amplifier plate
tuning
CAPACITOR: Part of ref. 2 17A.
Harmonic generator plate
tuning
1 l0C/ 2979
2 17B
*Parts which are applicable to Radio Receiver BC-624-AM !>nly.
)0
Z
0.
o
Bridge balancing
R-F plate tuning
3D9036V- 1
Bendix No. L 72948
AL74 1 14- 1
Zenith No. SG2 365
Bendix No. A104484
Zenith No. 22G756
Mixer grid tuning
S
CONT. or GO VT.
. DWG. or SPEC. No.
Aerovox type 30
Micamold type 306
Sprague type P-675 1
CAPACITOR: Part of ref. 2 16A.
-
:I
Bendix No. L75638
Aerovox type 4E
Solar type DEM
Cornell-Dubilier
Special
CAPACITOR: Part of ref. 2 16A.
2 17A
MFR. and DESIG.
or
AWS TYPE
Limiter filter
Limiter filter
Second i-f grid bypass
Audio B+ filter
2 16B
o·
RADIO RECEIVER BC-624 -A A N D BC-624-AM
FUNCTION
2 16C
VI
III
ft
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0.
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o
�
* 2 19
3DA l·55
22 1
1 10 / 2 5
3C302C
222
1 10C/ 3022
3CI074· 1 3
1 10C / 30 1 9
223
3CI074· 1 4
11 0C/30 1 8
224
3C1074· 1 5
1 10C / 3023
225
3C1074· 10
226
1 10C·302 1
3C 1074. 1 7
1 10C / 3020
227· 1
227·2
3C I074· 18
1 10C / 30 16
Bendix No. C563 1 5· 102
Antenna coupling
Radio frequency grid resonator
Bendix
Bendix No. A 104309
Zenith No. 20G4 1
Radio frequency plate resonator
Bendix
Bendix No. Al04308
Zenith No. 20G42
Mixer grid resonator
Bendix
Bendix No. A1043 1 3
Zenith No. 20G45
Harmonic amplifier plate
resonator
Bendix
Bendix No. A1043 1 1
Zenith No. 20G44
COIL: Radio frequency; two turns No. 14 S. D. tinned
copper wire; 1 3 1 32 " I. D. x 16" long; leads brought
out horizontally 9 / 32 " in opposite direction and ex·
tended 7 / 8 " over·all.
COIL: Radio frequency; 23 turns of No. 26 enameled
wire; wound on a form 1·27 / 32" x 1 1 / 16" dia.
Harmonic generator plate
resonator
Bendix
Bendix No. A104 3 1 0
Zenith No. 20G43
Oscillator plate resonator,
channel A
Bendix
Bendix No. AA10422 5· 1
Zenith No. SG2285
COIL: Same as ref. 227· 1 .
Oscillator plate resonator,
channel B
Oscillator plate resonator,
channel C
Oscillator plate resonator,
channel D
Mixer plate resonator
Bendix
Bendix No. AA 104206 - 1
COIL: Radio frequency; one turn No. 14 tinned copper
wire.
COIL: Radio frequency; two turns No. 14 S. D. tinned
copper wire; 2 3 / 64" I. D. x 1 /4" long; with lead ex·
tending 23/32" and then dropping down parallel at
right angles; one lead 1 1 1 16", other 1 / 2 " from center
coil.
COIL : Radio frequency; two turns No. 1 4 S. D. tinned
copper wire; 2 3/64" I. D. x 1 1 4" long; with one lead
brought down 1 / 2" from center of coil; theri bent 45 °
for 5 / 16", then straight down 1 / 8"; other end brought
down 1 /8".
COIL: Radio frequency; two turns No. 1 4 S. D. tinned
copper wire; 3/8" I. D.; one lead brought down 3/8"
from c enter of coil, other lead brought down 3 1 / 32"
from center of coil at approximately 40 degrees.
COIL: Radio frequency; one turn of No. 12 S. D. tinned
copper wire.
COIL: Same a s ref. 227· 1 .
227·4
COIL: Same a s ref. 227· 1 .
2C4424A / J8
1 10C / 30 1 5
COIL: 10 turns No. 22 enameled wire; permeability
tuned ; threaded form ; part of ref. 2 9 1 .
228·2
COIL: Same a s ref. 228· 1 ; part o f ref. 29 1 .
228·3
COIL: Same a s ref. 228· 1 ; part o f ref. 292.
228·4
COIL: Same as ref. 228· 1 ; part of ref. 292.
228·5
COIL: Same as ref. '228· 1 ; part of ref. 293.
228·6
COIL: Same as ref. 228· 1 ; part of ref. 293.
I
......
Limiter cathode bypass
Cornell·Dubilier
type SWL
Aerovox type 1468
Bendix
227·3
228· 1
......
CAPACITOR: Fixed; 1000 micromicrofarads ± 100/0 ;
500 volts DCW; mica.
*Parts which are applicable to Radio Receiver BC·624·AM only .
First intermediate frequency
grid resonator
First intermediate plate
resonator
Second intermediate frequency
grid resonator
Second intermediate frequency
plate resonator
Third intermediate frequency
grid resonator
Bendix No. A1043 1 2
Zenith No. 20G46
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TABLE OF REPLACEABLE PARTS
MODEL: RADIO SET SCR-624-A AND SCR-624-B
Reference
Symbol
Army Stod. No.
Navy Stock No.
British Ref. No.
COIL: Same as ref. 228- 1 ; part of ref. 294.
228-7
228-8
231
2Z7228. 1
232
1 10H/926
2Z7253.2
2 36
1 10H / 234
2Z2796- 1 50M
1 10C/ 3007
2Z72 7 1-72
237
NAME OF pART and DESCRIPTION
2Z7296-2M. l
1 10C / 3008
COIL: Same as ref. 228- 1 ; part of ref. 294.
CONNECTOR: 10-contact; male; similar to type P-4 10·
AB l / 16 less angle brackets.
CONNECTOR ASSEMBLY: 2-contact; antenna and
ground; over-all dimensions 2-1 /4" x 1- 1 / 16" x 3 /18".
POTENTIOMETER: 150,000 ohms; 1/2 watt; carbon;
taper "C" ; 1 / 4" diameter shaft 1 /8" long; slotted for
screw driver adjustment.
or
POTENTIOMETER: 150,000 ohms; 1 / 2 watt; carbon;
taper "A" ; 1 /4" dia. shaft slotted for screw driver ad­
justment.
POTENTIOMETER: 2000 ohms; 1 / 2 watt; carbon; taper
"A" ; 1 /4" diameter shaft 1 / 8" long; slotted for screw
driver.
or
241-1
24 1-2
241-3
243--1
POTENTIOMETER: 2000 ohms; 1 / 2 watt; carbon; linear
taper; 1 /4" dia. shaft with diamond knurl; slotted for
screw driver adjustmellt.
COIL-R.F. CHOKE: Same as ref. 162.
COIL-R.F. CHOKE: Same as ref. 162.
COIL-R.F. CHOKE: Same as ref. 162.
SOCKET-TUBE : Same as ref. 169- 1.
243-2
243-3
SOCKET-TUBE : Same as ref. 169- 1 .
SOCKET-TUBE: Same a s ref. 169- 1 .
243-4
243-5
SOCKET-TUBE: Same a s ref. 169- 1 .
SOCKET-TUBE : Same a s ref. 169- 1 .
243-6
SOCKET-TUBE: Same a s ref. 169- 1.
"'243-7
SOCKET-TUBE: Same as ref. 169- 1.
2Z7268.36
"'Parts which are applicable to Radio Receiver BC-624-AM only.
MAJOR ASSEMBLY:
::I
RADIO RECEIVER BC-624-A AND BC-624 -AM
FUNCTION
MFR. and DESIG.
or
AWS TYPE
Third intermediate frequency
plate resonator
Audio diode resonator
Receiver connector
Jones special
Bendix No. A 1 028 1 3
Zenith No. 58G64
Receiver input
Bendix
Bendix No. AAI04203-1
Zenith No. SG2286
"AUDIO" volume control
International
Resistance type CS
Stackpole
Carbon Co.
Chicago Tel.
Suppl y type 35
Chicago Tel.
Supply type 35
Bendix No. A 10299 1
Zenith No. 63G665
Stackpole Carbon
Chicago Tel.
Supply type 3 5
International
Resistance type CS
Chicago Tel. Supply
type 35
Bendix No. A 102992
Zenith No. 63G666
Audio squelch relay sensitivity
control
First audio grid choke
B + r-f choke
B + r-f choke
For tube JAN- 1 2AH7/GT,
oscillator audio squelch
For Tube JAN12-SG7, first I-F
For Tube JAN- 12SG7, second
I-F
For Tube JAN- 12SG7, third I-F
For Tube JAN-12C8, detector,
AVC and first audio
For Tube JAN- 12J5GT, second
audio
For Tube JAN- 12H6, limiter,
AVC delay
�
CONT. or GO VT.
DWG. or SPEC. No.
Bendix No. A1 1 3 1 9 1
Bendix No. A 1 1 3 190
,.
Z
0-
..
I
0
n
::III
0-
CIt
...,
..
I
...,
SOCKET-TUBE: 7-contact; with retainer ring.
For Tube JAN-9003, radio­
frequency amplifier
244-2
2 44-3
SOCKET: Same as ref. 244- 1.
SOCKET: Same as ref. 244- 1.
244-4
SOCKET: Same as ref. 244- 1 .
For Tube JAN-9003, mixer
For Tube JAN-9003, harmonic
amplifier
For Tube JAN-9002, harmonic
generator
For tube sockets
244- 1
2Z8657-3
1 l0H / 93 3
245
2ZK7856.5
246
2Z7642G
248
l lOF/ s04
1 10F/S08
2C4424A/ F l
1 10L/ 5 1
2 49- 1
2 49-2
249-3
2 49-4
250
2ZK8848- 1
1 10M / 2 376
251
2 52 - 1
3Z6747- 1 5
1 10C I 3004
3Z6747- 1 5
3Z67007-7
1 l0C/ 2998
3Z6700-54
3Z6700-7 1
2 52-2t
253-1
3Z6033- 1
RING: Socket retainer; formed with 3 crimps up, 3
crimps down; cadmium plated steel; over-all thick­
ness 1 / 8" .
RELAY: Single pole, single throw; 5000 ohms d-c re­
sistance coil ± 10% ; over-all dimensions 1-7 / 8 " ; 4
milliamperes ± 1 / 2 milliampere; operates with cur­
rent change of 0.2 milliamperes.
SHIFTER UNIT: Frequency; receiver, includes channel
slides and tuning controls.
SCREW-MOUNTING: Same as ref. 173- 1.
SCREW-MOUNTING: Same as ref. 173- 1 .
SCREW-MOUNTING: Same a s ref. 173- 1 .
SCREW-MOUNTING: Same as ref. 173- 1 .
SPRING: Phosphorous bronze; nickel plated; one end
rounded 3 / 16" radius; other end rounded 1 1 / 32 " ra­
dius; large end formed up 1 /8" high with a 1/4"
slot on side; small end has No. 2 0 hole in it.
RESISTOR: Fixed; 470,000 ohms ± 5 % ; 1 / 2 watt; carbon
or
....
-0
Bendix
Mounting receiver
Mounting receiver
Mounting receiver
Mounting receiver
For rube holder
to
to
to
to
Bendix No. A102882
A 106405
Zenith No. 193G48
Bendix No. AC57965- 1
Zenith No. SG2275
rack
rack
rack
rack
R-F stage grid leak
Bendix
Zenith
Bendix No. A 103943
Zenith No. 80G 161
Allen-Bradley type EB
Speer type SI- l / 2
Bendix No. A102975-474
Zenith No. 63G694
Allen-Bradley type E B
R-F stage AVC filter
Allen-Bradley type EB
Speer type SI-1 / 2
)10
Z
0I
",.
o
'"
n
:;g
0�
",.
I
�
Bendix No. A 1 02975- 1 04
Zenith No. 63G698
Speer type SI- l / 2
Allen-Bradley type E B
RESISTOR: Same as ref. 252- 1 . (Does not include Stock
No. 3Z6700-7- 1.)
RESISTOR: Fixed; 330 ohms ± 5 % ; 1 / 2 watt; carbon.
Audio diode load
RESISTOR: Same as ref. 2 5 3 - 1 .
Harmonic amplifier cathode
bias
tParts which are applicable to Radio Receiver BC-624-A only.
Bendix No. A 1 07657
Zenith No. 188G32
Channel selection
RESISTOR: Fixed; 100,000 ohms ± 1 0 0/0 ; 1 / 2 watt,
carbon
or
RESISTOR: Fixed; 100,000 ohms ± 20% ; 1 /2 watt,
carbon.
I
Amphenol type A
Cinch type 8493
Sigma type 40 1
Allied type G
R-F stage cathode bias
1 10C/ 3002
2 S 3-2
Bendix No. A 102980
Zenith No. 78G73
Squelch circuit
RESISTOR: Fixed; 470,000 ohms ± 20% 1 / 2 watt;
carbon.
RESISTOR: Fixed; 100,000 ohms ± 5 0/0 ; 1 / 2 watt; carbon
or
Amphenol type 78-7PT
Cinch type 9833
Allen-Bradley type E B
Speer type SI- 1/2
Parts . with no identification mark are applicable to both receivers.
Bendix No. A 1 02975-33 1
Zenith No. 63G692
'"
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n
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S
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11\
CD
TABLE OF REPLACEABLE PARTS
MODEL: RADIO SET SCR-62 4 - A AND SCR-62 4 - B
Reference
Symbol
* 2 5 3-3
2 54- 1
Army Stock No.
Navy Stock No.
British Ref. No.
3Z6568-3
1 l0C/ 3006
3Z6568- 1 1
2 54-2
* 2 54-3
2 5 5- 1
3Z680 1A8
1 l0C/ 3000
3Z680 1A8-7
2 55-2
256
3Z6 100-62
NAME OF PART and DESCRIPTION
RESISTOR: Same as ref. 253-1.
RESISTOR: Fixed; 6800 ohms ± 5 0/0 ; 1/2 watt; carbon
or
RESISTOR: Fixed; 6800 ohms ± 200/0 ; 1 / 2 watt; carbon.
RESISTOR: Same as ref. 2 54- 1.
RESISTOR: Same as ref. 2 54- 1. (Stock No. 3Z6568- 1 1
not included.)
MAJOR ASSEMBLY:
Ave delay
R-F stage plate filter
3Z6733-3
1 l0C / 3003
258
259
Allen-Bradley type EB
Speer type SI- l/2
Allen-Bradley type EB
Harmonic amplifier plate filter
AVC delay
RESISTOR: Same as ref. 2 5 5 - 1 .
Harmonic amplifier grid leak
Allen-Bradley type EB
RESISTOR: Fixed; 1000 ohms ± 5 0/0 ; 1 / 2 watt; carbon.
Mixer cathode bias
Allen-Bradley type EB
Speer type SI- l/2
Bendix No. A I02975- 102
Zenith No. 63G687
Allen-Bradley type EB
Speer type SI- l/2
Bendix No. A102975-334
Zenith No. 63G693
RESISTOR: Fixed ; 330,000 ohms ± 100/0 ; 1 / 2 watt;
carbon.
3Z6768- 1 3
RESISTOR: Fixed; 680,000 ohms ± 5 0/0 ; 1 watt; carbon
or
Mixer screen dropping
Bendix No. A I 02975- 185
Zenith No. 63G690
Allen-Bradley type EB
Speer type SI- l /2
Second audio grid leak
Erie type 505
Allen-Bradley type GB
Speer type SI- l
RESISTOR: Fixed; 680,000 ohms ± 200/0 ; 1 watt;
carbon.
3ZK5997A5
1 l0C/2996
RESISTOR: Fixed ; 7.5 ohms ± 5 0/0 ; 1 1 2 watt; carbon
or
2Z599'!- 1 3
RESISTOR: Fixed; 7.5 ohms ± 200/0 ; 1 / 2 watt; carbon
or
Speer type SI- l /2
3ZK600E5- 1 5
RESISTOR: Fixed ; 15 ohms ± 5 0/0 ; 1 / 2 watt; carbon.
(Note: This reference may use a 7.5 resistor or two
I S-ohm resistors in parallel.)
or
Speer type SI- l/2
RESISTOR: Fixed; 15 ohms ± 200/0 ; 1 / 2 watt; carbon.
(Note: This reference may use a 7.5 resistor or two
15-ohm resistors in parallel.)
* Parts which are applicable to Radio Receiver BC-624-AM only.
Bendix No. A18004-684
Zenith No. 63G72 1
Erie type 505
Allen-Bradley type GB
Speer type SI- l
3RC 3 1AE684M
RC20AE 1 50M
Bendix No. A I 02975-682
Zenith No. 63G696
RESISTOR: Fixed ; 1.8 megohms ± 20,0/0 ; 1/2 watt;
carbon.
RESISTOR: Fixed ; 330,000 ohms ± 5 0/0 ; 1 / 2 watt;
carbon
Or
s
CONT. or GOVT.
DWG. or SPEC. No.
Allen-Bradley type EB
Speer type SI- l /2
3Z6733-2
1 l0C / 29 1 9
MFR. and DESIG.
or
AWS TYPE
Mixer grid leak
RESISTOR: Fixed ; 1 .8 megohms ± 5 0/0 ; 1 / 2 watt; carbon
or
:::I
RADIO RECEIVER BC-624-A AND BC-624 -AM
FUNCTION
1 l0C / 2997
257
1\
Test meter shunt
Speer type SI- l /2
Speer type SI- l /2
Bendix No. A32 128
Bendix No. A 10297 5- 1 S0
Zenith No. 63G697
l>
Z
00 ''
I
�
11\
n
�
00
t.)
-1:<10
I
t.)
260
3Z6627-5
1 l0C/ 300 1
3Z6627- 14
261
3Z6 120-7
262- 1
1 l0C/2999
3Z6756-3
1 l0C/ 3005
3Z6756-5
262-2
263- 1
3Z6470-5
1 l0C/2915
3Z6470- 1 5
263-2
263-3
263-4
t264
3Z66 1O-50
RESISTOR: Fixed; 2 7,000 ohms ± 5 % ; 1 / 2 watt; carbon
or
Ha,monic generator plate filter
RESISTOR: Fixed; 2 7,000 ohms ± 200/0 ; 1 / 2 watt;
carbon.
RESISTOR: Fixed; 1200 ohms ± 5 % ; 1 / 2 watt; carbon.
Harmonic generator cathode
bias
Allen-Bradley type EB
Speer type SI- l /2
Bendix No. A 102975-122
Zenith No. 63G689
RESISTOR: Fixed ; 560,000 ohms ± 5 % ; 1/2 watt;
carbon
or
RESISTOR: Fixed; 560,000 ohms ± 10 % ; 1 / 2 watt;
carbon.
Harmonic generator grid leak
Allen-Bradley type EB
Speer type SI- l /2
Bendix No. A102975-564
Zenith No. 63G695
RESISTOR: Same as ref. 262- 1.
RESISTOR: Fixed; 4700 ohms ± 5 % ; 1 watt; carbon
or
First audio compensator
Mixer plate filter
RESISTOR:
RESISTOR:
RESISTOR:
RESISTOR:
First i-f plate filter
Second i-f plate filter
Third i-f plate filter
Oscillator plate filter
Same as ref.
Same as ref.
Same as ref.
Fixed; 1 0,000
263- 1.
263- 1.
263- l .
ohms ± 5 % ; 1 watt; carbon.
Allen-Bradley type EB
Speer type SI- l /2
265-2
266- 1
Oscillator plate filter
Audio diode load
Oscillator cathode bias
1 l0C/2910
3RC3 1AE272K
RESISTOR: Same as ref. 264.
RESISTOR: Same as ref. 264.
RESISTOR: Fixed; 2700 ohms ± 10 0/0 ; 1 watt; carbon
or
RESISTOR: Fixed; 2700 ohms ± 10 % ; 1 watt; carbon.
3Z6727-4
RESISTOR: Same as ref. 265- 1. (See ref. 282.)
RESISTOR: Fixed ; 270,000 ohms ± 5 % ; 1 watt; carbon
or
Audio squelch cathode bias
Oscillator grid leak
3Z6270- 1
1 l0C/29 1 1
3Z6727- 10
2Z6727-27
266-2
266-3
�
I
�
Bendix No. A10297 5-2 7 3
Zenith No. 63G69 1
Allen-Bradley type EB
Speer type SI- 1/2
1 l0C/ 2903
*264- 1
*264-2
265- 1
Allen-Bradley type EB
Speer type SI- l /2
RESISTOR: Fixed 270,000 ohms ± 10 % ; 1 watt; carbon
or
RESISTOR: Fixed; 270,000 ohms ± 20% ; 1 watt;
carbon.
RESISTOR: Same as ref. 266- 1.
RESISTOR: Same as ref. 266- 1. (Does not include stock
No. 2Z6727-27.)
Automatic volume control filter
First audio plate load
Erie type 505
Allen-Bradley type GB
Speer type SI- 1
Allen-Bradley type GB
Bendix No. A 1800-474
Zenith No. 63G7 17
Erie type 505
Allen-Bradley type
GB- 1035
Speer type SI- l
Bendix No. A 1 8004- 103
,..
Z
Erie type 505
Speer type SI· 1
Allen-Bradley type BG
Erie type 505
Speer type SI- 1
Bendix No. A I8004-272
Zenith No. 63G7 1 3
Erie type 505
Allen-Bradley type GB
Speer type SI- 1
Speer type SI- l
Bendix No. A 1 8004·274
Zenith No. 63G7 14
0I
�
'"
n
�
0�
,.
I
�
Erie type 505
Allen-Bradley type GB
Speer type SI- 1
tParts which are applicable to Radio Receiver BC-624-A only. Parts with no identification mark are applicable to both receivers.
*Parts which are applicable to Radio Receiver BC-624-AM only.
!l.
o·
'"
CD
S
::J
....
I
...,
...,
TABLE OF REPLACEABLE PARTS
MODEL:
Reference
Symbol
2 67· 1
RADIO SET SCR-624-A AND SCR-624 -B
Army Stock No.
Navy Stock No.
British ReI. No.
3Z6700·47
l lOC/ 1667
3Z6700·62
2Z6700·66
3Z6700·74
NAME OF PART and DESCRIPTION
RESISTOR: Fixed; 100,000 ohms ± 5 % ; 1 watt; carbon
or
MAJOR ASSEMBLY:
RADIP RECEIVER BC -624-A AND BC-624 -AM
FUNCTION
First i·f AVC filter
RESISTOR: Fixed; 100,000 ohms ± 5 % ; 1 watt;
carbon
or
RESISTOR: Fixed; 100,000 ohms ± 1 0 % ; 1 watt;
carbon
or
RESISTOR: Fixed; 100,000 ohms ± 10 % ; 1 watt;
carbon.
First i·f screen voltage divider
267·3
RESISTOR: Same as ref. 267· 1 . (Does not include stock
No. 3Z6700·74.)
First i·f screen voltage divider
267·4
RESISTOR: Same as ref. 267· 1 .
Second i·f AVC filter
267·5
RESISTOR: Same a s ref. 267· 1 . (Does not include stock
No. 3Z6700·74.)
Second i·f screen voltage
divider
267·6
RESISTOR: Same as ref. 267· 1 . (Does not include stock
No. 3Z6700·74.)
Second i·f screen voltage
divider
267·7
RESISTOR: Same as ref. 267· 1 . (Does not include stock
No. 3Z6700· 74.)
RESISTOR: Same as ref. 267· 1 . (Does not include stock
No. 3Z6700·74.)
RESISTOR: Fixed; 390 ohms ± 5 % ; 1 watt; carbon.
Harmonic aJl.lplifier screen
dropping
R·F screen dropping
3Z6039·2
269
1 l0C / 2 9 1 3
3Z6027·3
RESISTOR: Fixed; 270 ohms ± 5 % ; 1 watt; carbon.
270
1 l0C / 2909
3Z6047·2
RESISTOR: Fixed; 470 ohms ± 5 % ; 1 watt; carbon.
t27 1
1 l0C / 2 9 1 4
3Z6682-2
RESISTOR: Fixed; 82,000 ohms ± 5 % ; 1 watt; carbon
or
1 10C/2920
.3Z6682·7
* 2 7 1·2
tParts which are applicable
*Parts which are applicable
First i·f cathode bias
Second i·f cathode .bias
Third i·f cathode .bias
Third i·f screen dropping
RESISTOR: Fixed 82,000 ohms ± 1 0 0/0 ; 1 watt; carbon.
RESISTOR: Same as ref. 2 7 1 . (Does not include stock
No. 3Z6682·7.)
to
to
�
CONT. or GOVT.
DWG. or SPEC. No.
Erie type 505
Speer type SI· l
Bendix No. A 1 8004· 104
Zenith No. 63G704
Allen·Bradley type GB
Zenith No. 63G704
Allen·Bradley type GB
RESISTOR: Same as ref. 267· 1 . (Does not include stock
No. 3Z6700·74.)
268
MFR. and DESIG.
or
AWS TYPE
:s
Erie type 505
267·2
267·8
Q.
O·
'"
II
)0
Z
aI
§
n
II1II
a­
...,
olio
I
...,
Allen·Bradley type
Speer type SI· l
Erie type 505
Allen·Bradley type
Speer type SI· l
Erie type 505
Allen·Bradley type
Erie type 505
Speer type SI· l
Allen·Bradley type
Speer type SI· 1
Erie type 505
Speer type SI· l
Limiter filter
Radio Receiver BC624·A only. Parts with no identification mark are applicable to both receivers.
Radio Receiver BC·624-AM only.
GB
Bendix No. A18004·39 1
Zenith No. 63G7 1 5
GB
Bendix No. A 18004-27 1
Zenith No. 63G7 12
GB
Bendix No. A 1 8004·47 1
Zenith No. 63G7 16
GB
Bendix No. A18004-823
Zenith No. 63G722
t2 72
3Z67 12- 1 7
1 1 0C / 2904
3Z67 12-23
RESISTOR: Fixed; 120,000 ohms ± 5 0/0 ; 1 watt; carbon
or
RESISTOR:
carbon.
Fixed;
120,000
ohms
±
200/0 ;
1
Audio squelch compensating
watt;
"'2 72- 1
RESISTOR: Same as ref. 272.
Audio squelch compensating
RESISTOR: Same as ref. 272- 1 . (Does not include stock
No. 3Z67 12-23.)
Audio squelch compensating
3Z6506-2
2 74- 1
3Z6802A2- 1
1 10Z /2918
1 10C/ 2908
3Z68802A2- 1 1
3RC3 1AE225M
2 74-2
275-1
RESISTOR: Fixed ; 5600 ohms ± 5 0/0 ; 1 watt; carbon.
(De�eted in later models.)
RESISTOR: Fixed; 2.2 megohms ± 5 0/0 ; 1 watt; carbon
or
3Z6747-7
1 10C / 29 1 7
3RC3 1AE474
Audio squelch compensating
Erie
Speer
Allen-Bradley
Bendix No. AI8004-562
Zenith No. 63G720
Audio squelch coupling
Allen-Bradley type GB
Erie type 505
Speer type SI- l
Bendix No. A I 8004-225
Zenith No. 63G7 1 1
RESISTOR: Fixed; 2.2 megohms ± 1 0 0/0 ; 1 watt;
carbon
or
Speer type 51- 1
RESISTOR: Fixed; 2.2 megohms ± 200/0 ; 1 watt;
carbon.
RESISTOR: Same as ref. 274. 1 . (Does not include Stock
No. 3RC31AE225M.)
RESISTOR: Fixed; 470,000 ohms ± 5 0/0 ; 1 watt ; carbon
or
Erie type lI05
Allen-Bradley type GB
First audio screen dropping
First audio grid
RESISTOR: Same as ref. 275- 1. (Does not include stock
No. - 3RC3 1AE474.)
First audio grid
RESISTOR: Fixed; 18,000 ohms ± 5 0/0 ; 1 watt; ceramic.
AVC delay
1 10C /2907
"' 2 76- 1
RESISTOR: Same as ref. 2 76.
AVC delay
"'276-2
RESISTOR: Same as ref. - 2 76.
RESISTOR: Fixed; 1 800 ohms ± 5 0/0 ; 1 watt; carbon
or
Audio diode load
277
3Z6 1 80-2
1 10C/2906
3RC3 1AE 1 782K
278
i"
N
W
3Z6 1 50·2 3
1 10 C / 2905
First audio cathode bias
_
RESISTOR: Fixed; 1800 ohms ± 100/0 ; 1 watt; carbon.
RESISTOR: Fixed; 1 500 ohms ± 5 0/0 ; 1 watt; carbon
or
Bendix No. A I 8004-474
Zenith No. 63G7 19
Erie type 505
Allen-Bradley type GB
Speer type SI- l
RESISTOR: Same as ref. 275- 1.
3Z66 18- 1 4
Allen-Bradley_ type GB
Erie type 505
Speer type SI- l
RESISTOR: Fixed;
- 470,000 ohms ± 200/0 ; 1 watt;
carbon.
2 75-2
�
...
AVC diode load
275-3
t27 6
Bendix No. A 1 8004- 124
Zenith No. 63G706
Erie type 505
Allen-Bradley type GB
Speer type SI- l
*272-2
273
Allen-Bradley type GB
Erie type 505
Speer type SI-l
r
§
n
=
N
t
-
N
Allen-Bradley type
GB- 1835
Erie type 505
Speer type SI- l
Bendix No. A 1 8004- 183
Allen-Bradley type GB
Speer type SI- l
Erie type 505
Bendix No. AI8004- 182
Zenith No. 63G709
Erie type 505
Speer type SI- l
Second audio cathode bias
Allen-Bradley type GB
Erie type 505
Speer type SI- l
tParts which are applicable to Radio Receiver BC624·A only. Parts with no identification mark are applicable to both receivers.
·Patts which are applicable to Radio Receiver BC-624·AM only.
Bendix No. A 1 8004- 1 52
Zenith No. 63G707
::
"
:r.
o
:I
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.....
I
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o·
'"
CD
TAB LE OF REPLACEABLE PARTS
MAJOR ASSEMBLY:
MODEL: RADIO SET SCR-62 4 - A A N D SCR-624 - B
Reference
Symbol
2 79- 1
Army Stock No.
Navy Stock No.
British Ref. No.
NAME OF PART and DESCRIPTION
3RC3 1AE 182K
RESISTOR: Fixed; 1 800 ohms ± 1 0 0/0 ; 1 watt; carbon.
3Z6647-6
RESISTOR: Fixed; 47,000 ohms ± 5 0/0 ; 1 watt; carbon
or
1 l0C / 2 9 1 6
3Z6647- 14
FUNCTION
Squelch cathode bleeder
RESISTOR: Fixed; 47,000 ohms ± 1 0 0/0 ; 1 watt; carbon.
Squelch cathode bleeder
Audio diode load
Third i-f screen dropping
Third i-E grid leak
Audio diode filter
RESISTOR: 3300 ohms ± 5 0/0 ; 1 watt; ceramic. (Re­
placed by 265-2, 2 700 ohms, in later productions.)
Audio squelch cathode bias
Channel "A" crystal and plate
coil selector
286B
SWITCH-ROTARY: Bakelite; wafer style; 4-section, each
individually operated by attached lever; two 2-posi­
tion switches on each section.
SWITCH-ROTARY: Part of ref. 286A.
286C
SWITCH-ROTARY: Part of ref. 286A.
286D
SWITCH-ROTARY: Part of ref. 286A.
288
CONNECTOR-PLUG BOARD ASSEMBLY:
ref. 1 7 1.
3Z67 1 5- 1 5
282
1 l0C / 1664
3Z6330-2
286A
1 l0C / 29 1 2
3Z9827.26
1 l0F50 1
289
2C4424A/S2
291
2Z1000 1
292
2Z 1000 1
1 l0H / 9 1 2
1 l0K / 704
1 l0K / 705
Same as
MFR. and DESIG.
or
A WS TYPE
�
CONT. or GOVT.
DWG. or SPEC. No.
Erie type 505
Speer type . SI - 1
RESISTOR: Same as ref. 279- 1 .
RESISTOR: Same a s ref. 279- 1 . (See ref. 281.)
RESISTOR : Same as ref. 2 79- 1 .
RESISTOR: Same a s ref. 138-3.
RESISTOR: Fixed; 1 50,000 ohms ± 5 0/0 ; 1 watt; ceramic.
(Replaced by 2 79-3, 4700 ohms, in later production.)
2 79-2
*279-3
* 279-4
t280
t28 1
:::I
RADIO RECEIVER BC-624 -A AND BC-6 2 4 - AM
Allen-Bradley type GB
Speer type SI- 1
Erie type 505
Speer type SI- 1
Bendix No. A 18004.47
Zenith No. 63G748
Allen-Bradley type
GB- 1 545
Speer type SI- 1
Allen-Bradley type
GB-3325
Speer type 51- 1
Centralab crystal
Oak special
Yarley special
Bendix No. A 1 8004- 1 54
Zenith No. 63G708
Bendix No. A 1 8004-332
Bendix No. AA 102802- 1
Zenith No. SG2288
Channel "B" crystal and plate
coil selector
Channel "C" crystal and plate
coil selector
Channel "D" crystal and plate
coil selector
Receiver test-milliammeter
socket
CONNECTOR-PLUG BOARD ASSEMBLY: 12-contact
for 4 plug-in crystals.
Crystal sockets
Bendix
Bendix No. AC58428- 1
Zenith No. SG2293
TRANSFORMER-I. F.: 12 · megacycles; permeability
tuned.
Mixer to first i-f coupling
Bendix
Bendix No. AL73026- 1
Zenith No. SG2 195
TRANSFORMER-I.F.: 12 megacycles; permeability
tuned.
First i-E to second i-E coupling
Bendix
Bendix No. AL73206-2
Zenith No. SG2 196
*Parts which are applicable to Radio Receiver BC-624-AM only.
tParts which are applicable to Radio Receiver BC-624-A only. Parts with no identification mark are applicable to both receivers.
�
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2Z 1000 1
293
294
295
o
1 l0K / 706
2Z 1000 1.8
1 10K/707
2Z10000-22
1 l0K / 7 1 2
296A
2Z 10000-24
296B
1 l0C/ 3374
297
2ZKl 1 1 50- 1O
299
1 l0C / 3374
2ZK3290-4
VT- 1 3 5
2T 1 3 5
2 } 12}5GT
TRANSFORMER-I.F. : 1 2 megacycles; permeability
tuned.
Seconn i-f to third i-f coupling
Bendix
Bendix No. AL73026-3
Zenith No. SG2 197
TRANSFORMER-I.F.: 12 megacycles; permeability
tuned.
Third i-f to diode coupling
Bendix
Bendix No. AL73028- 1
Zenith No. SG2 198
TRANSFORMER: A.F .. : Input No. 1 primary doc resist­
ance 920 ohms; No. 2 primary doc resistance 6.9 ohms ;
secondary doc resistance 2450 ohms.
Audio input
Bendix No. A 103022
Zenith No. 95G35
TRANSFORMER, ASSEMBLY: Consists of output trans­
former and reactor; primary doc resistance 870 ohms;
secondary doc resistance 390 ohms; reactor doc resist­
ance 340 ohms ; mounted in can.
ASSEMBLY, RF. AND OSCILLATOR: Variable capaci­
tor assembly and associated circuit components.
Audio output and Audio B+
filter
Langerin Company
type L347
Rola Company
type 95035
Langerin Company
type L348
Rola Company
type 95G36
Bendix
Bendix
Bendix No. AA 103976- 1
Zenith No. SG2277
COUPLING-SHAFT: Consists of 2 hUb assemblies for
5 / 16" shafts with setscrews on opposite sides of
coupling plate; nickel plated brass.
TUBE }AN- 12}5GT: Detector amplifier diode; type
12J5GT.
Second audio
RCA
Kenrad
VT- 169
1 l02E / 185
2Tl69
2} 12C8
TUBE JAN- l 7C8: Duplex-diode pentode; type 12C8.
Selector, AVC, and first audio
RCA
Kenrad
VT-202
1 l0E/ 186
2T202
2J9002
TUBE }AN-9002 : Detector amplifier triode; type 9002.
Harmonic generator
RCA
Kenrad
VT-203
1 l0E/ 188
2T203
2}9003
TUBE JAN-9003 : Super-control amplifier pentode; type
9003.
R-F amplifier
RCA
Kenrad
TUBE }AN-9003 : Same as VT-203 above.
TUBE JAN-9003 : Same as VT-203 above.
TUBE JAN- 1 2AH7GT: Twin triode; type 12AH7GT.
R-F mixer
Harmonic amplifier
Oscillator and audio squelch
TUBE JAN- 12SG7 : High frequency amplifier pentode;
type 12SG7.
First i-f
TUBE JAN- 12SG7: Same as VT-209 above.
Second i-f
TUBE JAN- 12H6: Twine diode; type 12H6.
Noise limiter and AVC delay
Bendix No. A 103024
Zenith No. 95G36
Bendix No. AN90966- 1
Zenith No. SG2 192
»
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1l0E / 189
VT-203
VT-203
VT-207
VT-209
2T207
2 } 12AH7GT
1 l0E / 193
2T209
2 J 12SG7
RCA
Kenrad
RCA
Kenrad
1 l0E / 19 1
VT-209
.....
I
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VI
*VT-2 1 4
2T2 1 4
2 J 12H6
*Parts which are applicable to Radio Receiver B-624-AM only.
RCA
Kenrad
III
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III
TABLE OF REPLACEABLE PARTS
MODEL:
Reference
,symbol
40 1
RADIO SET SCR-624-A
Army Stock No.
Navy Stock No.
British Ref. No.
MAJOR ASSEMBLY:
NAME OF PART and DESCRIPTION
FUNCTION
CAPACITOR: Same as ref. 1 1 1 .
HV bypass
3H3 1 12
MOTOR: Ratchet type; 12 volts at 1 ampere.
For automatic tuning
Bendix
Colonial
General
Instrument
Bendix No. AC57992 - 1
Zenith No. SG2 193
ARMATURE: Ratchet motor; includes pawl; part of ref.
406.
Motor armature
Colonial
General
Instrument
Bendix No. AC I02 508· 1
Zenith No. SG2202
COIL: Relay; 975 turns No. 24 wire; 5.76 ohms ± 5 0/0
doc resistance.
Solenoid for ref. 406
Colonial
General
InstrUment
Bendix No. AA 102 5 36· 1
WHEEL: Ratchet; includes arm part of ref. 406.
Ratchet motor wheel
Colonial
General
Instrument
Bendix No. AA I02 5 19. 1
AC 59900
Zenith No. GG2200
Allied
Bendix No. A 1028 17
Zenith No. 195G 5 1
407
3H3 1 12 / A 1
408
3Cll09- 1
409
3H31 12/Wl
1 l0K /708
1 10K/ 72 3
1 10M / 2 32 3
2Z7642AR
1 10 F / 502
4 1 1-2
4 12
2Z650-A7374
4 16
2Z8799" 1 5 3
417
2Z8799- 1 5 1
4 18- 1
2Z8639-3
RELAY: Motor control; single
solder terminals on end.
pole
single
throw;
2
Lo(:king relay
Cornell-Dubilier
Aerovox
Bendix No. A I028 16
Zenith No. 22G779
RELAY: Same as ref. 4 1 1 - 1 .
Motor control
RELAY: Antenna; combination double pole double
throw and single pole, single throw.
Antenna chan�eover
Clare
Bendix No. C58 180
Zenith No. 195G45
SOCKET SO- 1 5 3 : Female contact;
cable connector.
Antenna connection
Amphenol
Bendix No. AC58 1 36· 1
Zenith No. 78G77
SOCKET . SO- 1 5 1 : Male contact; 18·contact.
Control circuit
Amphenol type
46-R4- 1 59
Bendix No. AAI02 399· 1
Zenith No. 78G78
CONNECTOR: Female contact; 8-contact; polarized.
Transmitter control circuit
Jones
Bendix A I028 1 2
Zenith No. 58G67
CONNECTOR: Same as ref. 4 18- 1 .
CONNECTOR: Female contact; 10-contact; polarized.
Power input to transmitter
Receives connection
Jon�s
Bendix No. A I 02Z8 14
Zenith No. 58G66
CONNECTOR: Male contact; 10-contact; similar to type
P-4 1O-AB 1 / 16" less angle brackets.
Power input to rack
Amphenol
Bendix No. AAI02437·1
Zenith No. 78G75
Ground plug
General Radio
Bendix No. A102875·2
Zenith No. 58G69
1 10F / 494
I-contact; coaxial
1 10H/ 585
1 10H/ 9 1 6
1 10H /925
4 1 8-2
4 19
2Z8639-4
420
110H/927
2Z8799- 147
42 1
1 10H/922
2Z72 52
1 10H / 92 8
CONNECTOR: Male contact; banana plug; hex bead
1 / 4" high; 5 / 16" across fiats tapering to a 5 / 32" d ia.
circle; over-a11 length 1-5 / 16 inches.
o
::s
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CONT; or GO VT.
DWG. or SPEC. No.
1 10C/ 299 1
Motor solenoid resonating
1 10K / 699
411-1
MFR. and DESIG.
or
AWS TYPE
�
RACK n-24 4 -A
CAPACITOR: Fixed; 2 micromicrofarads + 0 . 5 % microfarads - 0 microfarads; 25 volts DCW, 60 cycles;
oil paper; in metal case.
3DB2.816
402
406
AND SCR-624 -B
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422
2Z7380-244A/PI
426
3Z9509- 1
427A
3Z8 3 1 3-2
CONNECTOR: Male contact; 2 banana pins ; 7/8" long;
2 soldeting lugs.
Antenna plug
Bendix
Bendix No. AAI027 18- 1
Zenith No. SG2395
SWITCH: Push; double pole, single throw.
Tuning release
Arrowhart and
Hageman
Bendix No. A29B43- 1
Zenith No. 85G75
SWITCH: Jack; 4-pole; single throw; normally dosed ;
circuits individually actuated.
Motor positioning
Bendix
Bendix No. A I02537- 1
Zenith No. SG220 1
Bendix
Bendix No. A I0274 1C
1 10H/923
1 10 / 49 1
427B
1 10 F / 5 0
427C
427D
43 1 - 1
2Z7380-244A / S l
1 10M/2325
SWITCH: Jack; part of ref. 427 A.
Motor positioning
SWITCH: Jack; part of ref. 427A.
Motor positioning
SWITCH: Jack; part of ref. 427A.
SCREW : Machine, cold drawn steel ; cadmium plated;
head pointed black; slotted; 6-32 x 1 / 4" thread; over-
Transmitter cover retaining
Motor positioning
all length 7 / 16".
43 1-2
SCREW: Machine; same as ref. 43 1- 1 .
Transmitter cover retaining
43 1-3
SCREW: Machine; same ' as ref. 43 1 - 1 .
Transmitter cover retaining
4 3 1 -4
SCREW: Machine; same a s ref. 43 1 - 1 .
Transmitter cover retaining
MODEL: RADIO SET SCR-S 22-A
2Z1880A
CASE : Case CS-80-A; a housing for Rack FT-244-A, Ra­
dio Receiver BC62 4-A, BC624-AM, or BC-624-C, and
Radio Transmitter BC-62 5-A or BC625-AM; equipped
with 4 shockmounts and a ground strap
or
MAJOR
ASSEMBLY:
�
-
For housing rack and
transmitter-receiver assembly
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2 Z 1 880C
CAS E : Case CS-80-C; same as Case CS-80-A but with
addition of a base plate for a quickly detachable
mounting.
For housing rack and
transmitter-receiver assembly
2Z840 1 -5PH 1 2
MOUNT: Vibration; cadmium plated steel and rubber.
Shockmount for case
140 1-2
MOUNT: Same as ref. 140 1- 1 .
Shockmount for case
140 1-3
MOUNT: Same a s ref. 1 40 1 - 1 .
Shockmount for case
140 1-4
MOUNT: Same a s ref. 1 40 1 - 1 .'
Shockmount for case
140 1 - 1
CASE CS-IO-A AND CASE CS-IO-C
�
�
I
Lord type 1 50PH 1 2
Bendix No. C56354- 10
Zenith No. 77G8
Bendix
Bendix No. A I02900-2
Zenith No. 1 12G680
1 10M / 12 5
1402- 1
SCREW: Cap; same as ref. 3 5 3- 1 .
Shockmount to case mounting
1 402-2
SCREW: Cap; same as ref. 353� 1 .
Shockmount to case mounting
1 402-3
SCREW: Cap,; same , a s ref. 353- 1 .
SCREW: Cap; same a s ref. 35.3- i .
Shockmount to case mounting
1 402-4
1 403- 1
6 14904. 1 5
1 l0M / 2 329
1 40 3-2
...
I
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...
1 40 3- 3
1 403-4
. .
SCREW: Capr hex head 3/ 16" thick x 7 / 16" dia. ; 1 / 4-26
thread full length; over-all dimensions 1 7 / 32 " x 7/ 16"
x 1 /4".
Shockmount to case mounting
Dynamotor unit to case
mounting
SCREW: Cap; same as ref. 1403- 1 .
Dynamotor unit to case
mounting
SCREW: Cap; same as ref. 1403- 1 .
Dynamotor unit to case
mounting
Dynamotor unit to case
mounting
SCREW: Cap; same a s ref. 1403- 1 .
r
"
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I
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CD
Q.
0-
TABLE OF REPLACEABLE PARTS
MODEL:
Reference
Symbol
MODEL:
200
RADIO SET SCR- 5 2 2 - A
Army Stock No.
Navy Stock No.
British Ref. No.
MAJOR
NAME OF PART and DESCRIPTION
'"
CD
ASSEMBLY:
FUNCTION
AND
CASE CS-80-C
BASE-CASE : Consists of an upper base stamped from
0.064" thick sheet aluminum; over-all dimensions
0.0564" x 12- 1 3 / 32" x 18-29 / 32 " ; 4 rubber shockmounts spaced to fit the case; 3 each shakeproof fastener studs and cross pins assembled at one end to
secure base assembly to Mounting Ff-488.
Case base plate
Colonial
Colonial No. 48995
2Z672 1-488
MOUNTING Ff-488: A formed sheet metal mount ; overall dimension 1 / 2" x 12- 1 / 2 " x 1 7 " .
For case CS-80-C
Bendix
Bendix No.
OAL75224- 1
MAJOR ASSEMBLY:
RADIO SET SCR-624 -A
3Z9824-36
SWITCH: SPST; push-button type.
"RADIO PRESS T O TALK"
­
Tele:
20 1-2
POST: Binding; same as ref. 20 1 - 1 .
Same as 2 0 1 - 1
201-3
POST: Binding; same as ref. 20 1 - 1 .
"COM." connection to Con­
trol Box BC 1 1 7 1-A
20 1-4
POST: Binding; same a s ref. 2 0 1 - 1 .
"TEL'-' connection to Control
Box BC l 1 7 1-A
20 1-5
POST: Binding; same a s ref. 20 1 - 1 .
"K" connection to
Box BC- 1 17 1-A
3Z737-4
CONTROL BOX 1 1 76-A
Bendix
AA 1 10389- 1
Eby
A 1 10255
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200
3Z9849. 109
SWITCH: S.P. ; 3-throw; Cat. No. 88 1 5 .
"Send-Rec." switch
Cuttler-Hammer
A 1 1 3258
201-1
3Z737-4
POST: Binding; type No. Sergeant S50 1 4 ; 1 / 2 " diameter;
3 / 4" long No. 8.32" x 1 / 2 " threads.
"K" connection (to telephone
line)
Eby
A l l02 5 5
20 1-2
POST: Binding; same as ref. 201- 1 .
"C" connection
Jine)
201-3
POST! Binding; same a s ref. 20 1 - 1 .
"T"
connection (to telephone
line)
,.
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Control
(to telephone
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MAJO R ASSEMBLY: CONTROL BOX BC- 1 3 1 3
RADIO S E T SCR-62 4 - B
:::s
CONT. or GOVT.
DWG. or SPEC. No.
2Z56 1
"TEL" connection to
phone EE-S-A and EE-S-B
MODEL:
CS-80-A
MFR. and DESIG.
or
AWS TYPE
POST: Binding; type Sergeant SS- 14; 1 / 2 " diameter;
3/4" long; No. 8 / 32 " threads.
201-1
CASE
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202
2Z8799·2 3
203
....
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CONNECTOR: 4·contact socket; box mounting, amph
No. 1 0H· 3 9 5 .
RESISTOR: Variable; comp; 1 000 ohms :!: 2 0 % ; 2 - 1 /4
watt; JAN "A" taper; 1 /4" shaft; case 1 · 3 / 3 2 "
diameter x 9 / 1 6" thick; hexnut and fiat washer or
bushing.
Connection to Telephone EE·
8·A or EE·8-B
Volume control
MOD E L : RADIO S ET SCR·624·A A N D S.C R.624.B
....
..0 '
A 1 1 3 2 44
Allen Bradley
JU 1 0 2 1 /P2040
ERV3 0ERIU· I 02
MAJOR ASSE M B LY : CONTROL BOX BC·1 1 7 1 ·A
210
3 Z98 2 4 · 3 6
SWITCH: SPST; push. button type.
"RADIO PRESS TO TALK"
Bendix
AA I I 0 3 89- 1
211
3 Z98 2 2 · 6 5 . 1 2
SWITCH: Rotary; S.P.; 4·position non.shorting switch
equipped with dents and stops; bakelite wafer.
�'CHANNEL" selector control
Oak
C60479
212
2 Z8 7 99- 1 4 7
S OCKET: 1 2-contact; male and panel m ounting type.
Receptacle for Cord CD-8 1 0·A
Bendix
AA I 02 4 3 7- 1
2 1 3· 1
3 Z7 3 7·4
POST: Binding; type No. Sergeant sS. 1 4 ; 1 /2" di­
ameter 3 /4" long; No. 8 - 3 2 " x 1 /2 " .
"TEL" connection to Tele·
phone EE·8·A or EE·8·B
Eby
A I I 02 5 5
2 1 3· 2
2 1 3· 3
POST: Binding; same a s ref. 2 13 - 1 .
POST: Binding; same as ref. 2 1 3· 1 .
2 1 3·4
POST: Binding; same as ref. 2 1 3· 1 .
2 1 3· 5
POST: Binding; same as ref. 2 1 3· 1 .
Same as 2 1 3- 1
"COM" connect to Control
Box BC· 1 1 76·A
"TEL" connection to Control
Box BC· 1 1 7 6-A
"K" connection to Control
Box BC- 1 1 7 6-A
M O D E L : RA D I O S ET SCR624·B
I
to.:!
American Phenolic
210
3 Z9849. 1 09
211
212
3 ZK98 2 5 · 6 5 . 1 2 SWITCH: S.P.; 4-position; non-shorting; 1 -9 / 1 6" di­
ameter x 7 / 1 6" deep; 1 /4 " shaft; oak ' type "H"
spedal.
2 ZK7 1 2 2 . 2
CONNECTOR: 1 2-Contact; box mounting; fits PL· 1 69.
2 1 3- 1
3 Z7 3 7-4
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MAJOR ASSE M B LY : CONTROL BOX BC.1 3 1 4,
"SEND·REC." switch
Cutder-Hammer
A1 1 32 5 8
"CHANNEL" selector control
Oak
C60479
Receptacle for Cord CD·8 1 0-A
Amphenol
# 1 0H- 1 5 8 P
AA I 02 4 3 7 - 1
POST: Binding; type No. Sergeant SS. 1 4 ; 3 used,
hexnut and lock washer.
"K" connection (to telephone
line)
Eby # 66 3 9
OA 1 1 0 2 5 5
2 1 3· 2
POST: Binding; same as ref. 2 1 3· 1 .
2 1 3-3
POST: Binding; same a s ref. 2 1 3" 1 .
"C" connection (to telephone
line)
"T" connection (to telephone
line)
SWITCH: S.P.; 3 ·throw; Cat. No. 88 1 5 .
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M O D E L : RADIO SET SCR·624·B
Ref�re"ce
Symbol
Army Stock No.
Navy Stock No.
British Ref. No.
2 14
215
M AJ O R ASSEM B LY: CONTROL BOX BC·1 3 1 4
MFR. and DESIG.
or
A WS TYPE
FUNCTION
CONNECTOR: 4.socket contact; box mounting fits
PL· 1 69.
,RESISTOR: Variable; comp; 1 000 ohms :': 20%;
2 . 1 /4" watt; JAN "A" taper; 1 /4" shaft; case
1 · 3 / 3 2 " diameter x 9 / 1 6" thick; hexnut fiat washer
on bushing.
Connection to Cord CD·8 1 0·A
AN 3 1 0 2 A. 1 4S·2S
MIL·C· 5 0 1 5
Volume c;ontrol
Allen Bradley
JU 1 0 2 1 /P2040
ERV 3 0ER 1 U· 1 02
3 Z98 2 4' 3 6
SWITCH: SPST; push. button type.
"RADIO PRESS TO TALK"
Bendix
AA· l1 0 3 89· 1
221
2 ZK7 1 2 8 . 3
PLUG: 1 8·contact; male; with special locking ring.
Connection to Rack FT·244·A
Bendix
AC60490. 1
222
2 Z8 799· 1 47
SOCKET: 1 2·contact; male; panel mounting type.
Bendix
AA 1 0 2 4'3 7 . 1
223
3 Z9849. 1 9
SWITCH: SPDT; toggle.
Connection to Cord CD·9 5 1 .A,
to Cord CD.8 1 0.A, and to
Control Box BC· 1 1 7 1 ·A
"LOCAL REMOTE" control
H and H
A498 5 · 1
224
3 ZK98 2 2 ·6 5 . 1 2 SWITCH: 1 .pole; 4.throw; rotary; non.shorting switch
equipped with dents and stops; bakelite wafer.
"CHANNEL" selector control
Oak
C60479
225·1
3 Z7 3 7·4. 5
POST: Binding; type No. Sergeant SS· 1 4; 1 /2 " di.
ameter 3 /4" long No. 8 · 3 2 x 1 /2 " threads.
"K" connection to Telephone
EE·8·A or llE-8.B
Eby 6639
OA l l 02 5 5
2 2 5·2
3 Z7 3 7·4. 5
POST: Binding; same as ref. 2 2 5 · 1 .
"COM" connection to Tele·
phone EE·8·A or EE·8·B
..
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2 2 5· 3
3Z7 3 7·4. 5
POST: Binding; same as ref. 2 2 5 · 1 .
"TEL" connection to Tele·
phone BE·8·A or EE·8·B
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226·1
3 ZK6008B2.6
RESISTOR: Fixed; 820 ohms; :': 1 0 % ; 1 watt: carbon.
Microphone "T·PAD"
attenuator
Erie
C600 5 0· 8 2 0
2 26"2
3ZK6008B2·6
RESISTOR: Same as ref. 2 2 6· 1 .
Same a s 2 26· 1
227
3 ZK 5 996H8· 1
RESISTOR: Fixed: 6.S ohm :': 1 0 % ; 1 watt; carbon.
Microphone "T·PAD"
attenuator
Erie
A 1 8 1 5 0·068
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MAJOR ASS E M B LY: CO NTROL BOX BC·1 1 75·A
220
:III
:::I
CONT. or GOVT.
DWG. or SPEC. No.
NAME OF PART and DESCRIPTION
M O D E L : RADI� S ET SC R·624·A
�
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..
TABLE OF REPLACEABLE PARTS
,..
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228
2 ZK.7 6 5 8 - 1 9
229
3 DA2 5 0 - 3 0
RELAY: SPDT; SPST, normally closed; 1 2 -volt; �OO
ohm; solenoid.
CAPACITOR: 0.25 microfarad; 400 volts doc working
voltage; type 430.
Transmit-Receive switching
Bendix
A l l 02 8 8- 1
Coupling
Aero
A I 04 5 6 1
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M O D E L : RADI O S ET SCR·624.B
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MAJ O R ASSE M B LY: CONTRO L BOX BC·1 3 1 2
220
22 1
3 Z9849 . 1 09
2 ZK.7 1 2 8 . 3
SWITCH: S.P.; 3-throw, Cat. No. 8 8 1 5 .
CONNECTOR: 1 8-contact, socket type, zinc alloy shell
"SEND-REC." switch
Connection to Rack FT-2 44-A
222
2 ZK.7 1 2 2 . 2
CONNECTOR: 1 2-contacts; box mounting.
223
3 Z9 8 5 7-60
SWITCH: SPOT; toggle.
Connections to Cord CD-9 5 1 -A,
t o Cord CD- 8 1 0-A, and to
Control Box BC- 1 3 1 4
"LOCAL-REMOTE" control
224
3 ZK.98 2 5 -6 5 . 1 2 SWlTCH: S.P.; 4-positioD; non,shorting; 1 -9 / 1 6"
diameter x 7 / 1 6" deep; 1 /4" shaft; Oak type "H"
special.
�Z7 3 7-4. 5
POST: Binding; type No. Sergeant SS- 1 4; 1 /2 " diameter; 3 /4" long; No. 8 - 3 2 x 1 /2 " threads.
225-1
2 2 5-2
POST: Binding; same as ref. 2 2 5 - 1 .
22 5-3
POST: Binding; same a s ref. 2 2 5 - 1 .
Cuttler-Hammer
Amphenol
1 0H- 1 6 1
Amphenol
1 0H- 1 5 8 P
A 1 l 32 5 8
AC60490- 1
H and H
# 2 1 3 49-CS
A498 5 - 1
"CHANNEL" selector switch
Oak
C60479
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"K" connection (to Loudspeaker LS- I 0-A)
Eby # 66 3 9
OA l l 02 5 5
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RC20BF82 0K
JAN-R- l l
RC20BF I 00K
JAN-R- l l
"COM" connection (to Loudspeaker LS- I 0-A)
"TEL" connection (to Loud.
speaker LS- l 0A)
Microphone "T-PAD"
attenuator
AA I 0 2 4 3 7 - 1
2 2 6- 1
3RC20BF8 20K
RESISTOR: Fixed; comp; 8 2 ohm ± 10%; 1 /2 watt.
2 26-2
227
3RC20BF I 00K
RESISTOR: Same as . ref. 2 26- 1 .
RESISTOR: Fixed; comp; 10 ohms; ± 1 0% ; 1 /2 watt.
Same' as ref. 2 2 6- 1
Microphone "T-PAD"
attenuator
228
2 Z7 5 8 8- 5 7
RELAY: 1 SPDT; 1 SP.sT; normally closed; 1 2-volt;
3 0 0-ohm coil.
Transmit-Receive switching
Potter Brum
# LT-S 2
A ll 0288- 1
229
3 DA2 5 0- 3 0
CAPACITOR: 0.2 5 ' microfarad; 400-volt doc working
voltage type 430.
Coupling
Aero
A I 04 5 6 1
2 3 0- 1
2,Z7 5 8 5 - 7 4
RELAY: Coil 1 5 0 ohms; doc nominal coil potential 1 2
volts; gives continuous service at 8-volt maximum.
Remote channel "0" control
relay
Allied # TSX- 1 3
A2 1 3 3 1 6
2 3 0-2
RELAY: Same as .ref. 2 3 0- 1 .
Remote channel "C" control
relay
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TABLE OF REPLACEABLE PARTS
M O D E L : R A D I O S ET SCR·624·B
Reference
Symbol
Army Stock No.
Navy Stock No.
British ReI. No.
NAME OF PART and DESCRIPTION
2 30·3
RELAY: Same as ref. 2 3 0- 1 .
2 3 0·4
RELAY: Same as ref. 2 3 0· 1 .
231
CONNECTOR: 4-socket contacts.
232
233
3RC20BF2 2 0K
RESISTOR: Variable; comp; 1 00 0 ohms :l:: 2 0 % ;
2 . 1 /4 watt; JAN "A" taper; 1 /4" shaft; case
1 · 3 / 3 2 " diameter x 9 / 1 6 " thick, hexnut and flat
washer on bushing.
RESISTOR: Fixed; comp; 22 ohms :!: 1 0 % ; 1 /2 watt.
FUNCTION
Remote channel "B" control
relay
Remote channel "A" control
relay
Connection to Telephone
EE-8.A, or EE·8·B
MIL-C· 5 0 1 5
Volume control
Allen Bradley
JU 1 02 1 /P2 040
ERV 3 0ER I U· I 02
Microphone "T·PAD"
attenuator
RC20BF 2 2 0K
JAN·R. I I
CAPACITOR: Fixed; 3 0 microfarad; 450 volts DCW;
dry electrolytic; aluminum can 1 /2 " x 4·3 /8".
+ 3 1 0·volt output filter
P.R.M.
A I 1 0890
C I 02
3DKB 3 0- 1 2
1 50-volt output filter
P.R.M.
A l l 08 9 1
C103
3 DKB6000
CAPACITOR: 3·section; 3 0· 1 5· 1 0 microfarad; 2 5 0
volts DCW; electrolytic; aluminum can 1 - 3 /8" x
3 · 1 /4".
CAPACITOR: 6000 microfarad; 1 5 volts d·c working
voltage; Mallory Part No. B·94 7 8 2 . 1 .
+ 1 3·volt d·c output filter
P.R.M.
C60696
+ 1 3·volt doc output filter
Securing Tube JAN·6X 5 GT
P.R.M.
A l l 0887- 1
For medium voltage supply
capacitor
P.R.M.
A l l 08 8 7 · 2
For high-voltage supply
capacitor
P.R.M.
A I I 08 8 7 · 3
Mounting capacitor for
CDKB6000
P.R.M.
A I I 0880
- 1 5 0 volts d·c output filter
P.R.M.
C60698
+ 1 3 volts d·c output filter
P.R.M.
C60697
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2 ZK 2 6 5 0· 3
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MAJOR ASSEM B LY: R ECT I FI E R RA·62·B·C
3 DKB 30· 1 1
2 ZK 2 6 5 0· 7
Li02
3CK 3 3 6· 3 9
L103
3CK 3 3 6-40
CAPACITOR: Same a s ref. C I 0 3 .
CLAMP: Tube: 1 · 1 /4" diameter; cadmium plated
steel band; 9 / 1 6" wide x 1 . 1 /4" dia.; 2 mounting
feet; overall height 3 /4".
CLAMP: Capacitor; cadmium plated steel band, 9 / 1 6 "
wide, 1 . 1 /4" diameter.
CLAMP: Capacitor; cadmium plated steel band; 9 / 1 6"
wide, 1 - 1 /2" diameter; 2 mounting feet; overall
height 3 /4".
CLAMP: For capacitor; 1 /3 2 " cadmium plated steel,
3 /4 " wide, 2" diameter; adjusted by screw through
ears on band; three mounting feet; 1 . 1 /8" overall
high.
COIL: A·F filter choke; 2 section; 2 50 ohms d·c per sec·
tion; metal case; 2 ·9 / 1 6" x 3· 1 / 1 6" x 3 · 1 /8" high.
COIL: A·F filter choke; .0 1 henry; . 1 5 5 ohm d·c; :!: 8 % ;
metal case; 2· 5 / 1 6" x 3 · 3 / 1 6" x 3 · 1 /4".
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CONT. or GO VT.
DWG. or SPEC. No.
C101
2 ZK 2 6 5 0·8
&..
MFR. and DESIG.
or
A WS TYPE
AN 3 1 0 2 A· 1 4S·2S
M O D E L : RADIO S ET SCR·624·A OR SCR·624·B
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MAJ O R ASSE M B LY: CONTROL BOX BC·ll 1 2
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3CK3 36-38
#
J 102
3EK430 1·9
2Z7 1 38. 1
2ZK5854·2
COIL: Filter choke; 10 henry; 900 ohm ± 8 0/0 ; A. P. '
Foster Co. ; No. 1322; Mallory dwg. No. A-82263- 1 .
+ 3 10 volts d·c output filter
P.RM.
L74487
CORD: Line, Mallory part No. B84145 125.
Line cord
P.RM.
A1 15716
* FORD: Line, 2 5 ft.
* CONNECTOR: Male contact; amphenol No. 61-M1 O ;
1 10 volts ; 6-cyc1e; 2 recessed male prongs; steel shell.
Line cord
A-C input
P.RM.
P.R.M.
A 1 10733
A 1 10882 .
Voltage selector control
P.R.M.
A 1 10878
P.RM.
C60683
P.RM.
A 1 10885
Relay limiting
P.R.M.
A 1 10884
Regulator ; carbon pile shunt
P.RM.
A 1 10886
P.R.M.
C60695
Leland Electric
A1 15717
P.RM.
C60694
KNOB: Bar type with pointer; Mallory part No.
A- 133575- 1 ; 5/8" wide x 1- 1 1 / 16" long x 3 / 4" high,
black enamel finish; fits 1 /4" shaft.
RELAY: Plate voltage; SPST; normally open; 8000
ohm coil; over-all 2-3/ 16" x 1- 1 /2 " x 1-5 / 8".
KI01
2ZK7684-5
K I02
3H4845
R101
3ZK66 15-73
R I02
3ZK6250-43
RI03
3ZK5993-9
R l04
3HK4970-2
R 104
3HK4970-2
*REGULATOR: Voltage; Leland No. B-2386; carbon
pile; solenoid actuated type; 2- 1 3 / 16" diameter x
4-7 / 16" over-all.
tREGULATOR: Voltage; Leland No. B- 12-CK- 177.
S101
3ZK9825-78
SWITCH: Rotary wafer; 3-seaion; 3-pole; 6-position.
RECTIFIER: Copper sulfide . type IS36B7M; full wave;
bridge; plate 2- 1 / 2 " square; stacked APP. 7- 1 / 2 " high.
RESISTOR: 1 5 ,000 ohms ± 5 0/0 ; 20-watt; Cat. No. 2 HJ
vitreous.
RESISTOR: 2 500 ohms ± 5 0/0 ; 10 watts; vitreous.
RESISTOR: 30 ohms ± 1 0 0/0 ;' 80 watts; cathode No.
8H]3; vitreous.
+ 13 volts doc supply
+ 3 10 volts doc output
+
13 volts doc output control
+ 1 3 volts doc output contr.ol
Voltage selector
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tUsed as Rectifier RA-62-C.
MAJOR ASSEMBLY:
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ANTENNA MAST MA·7·A
6QK9270
BLOCK AND TACKLE : One double sheath block, one
triple sheath block, each with hook; 1 50 ft of rope.
Mast erection
Bendix
AC60947- 1
2AK3207-9
* SHACKLE: "U" shaped; steel plated; 5 / 16" dia. ;
screw with eyelet type head ; working length 1 - 1 /4".
Stays coupling
W.H.W.
A 109833
*No longer supplied.
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TABLE OF REPLACEABLE PARTS
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MAJO R ASSEMBLY:
Reference
Symbol
Army Stock No.
Navy Stock No.
British Ref. No.
NAME
OF PART and DESCRIPTION
FUNCTION
MFR. and DESIG.
or
AWS TYPE
Ring and chain coupling to
anchor
W.H.W.
A. 109834
SHACKLE: 3 / S " screw shackle.
BASE PLATE ASSEMBLY: Steel base plate, S" square,
1 /4" thick ; two "V" shaped uprights.
Stays coupling
Mast base support
W.H.W.
Bendix
A I09964
AN9 1 523- 1
BOOM END : Steel ; tubular; 3- 1 / 16" O.D.; 2 - 1 /S" I.D.;
;'V" shaped end plate; over-all length 1 1- 7 / S " .
Boom coupling to stays, vangs
and anchor
Bendix
AC742 5 .1 - 1
6QK50200-5
HAMMER: Sledge; 6-pound ; 22" handle.
Shake driving
L.A.B.
A 109960
6ZK 1S04-2
CHAIN WITH RING :
chain.
Stays coupling to anchor .
Bendix
C60350
2AK3345.2
STAKE : 7 / 16" diameter, 1 2 - 1 / 4 " long.
Bendix
C60355
2 AK2007A / C 1
CLAMP: Steel ; 2 semi-circular sections; 3" wide 5-29 / 32 "
·
long, 1 / 16" thick; -6 bolts; notch in one section.
Bendix
C60362- 1
2Z2633- 1 3
tClamp: · Coaxial cable.
Bendix
A 1 12325
6RK57422
WRENCH: "T" shaped socket; steel; fits 1 1 / 16" hex
nut.
B.G.I.
A 1099 1 1
L.A.B.
A l 109 10
A 1099 10- 1
#
2 AK20S5
2AK2007 A / B 1
6RK57022
Steel ring;
3"
1 . .0.;
16-link
Base plate securing
Mast
to
mast
base securing
.
Securing coaxial cable in mast
WRENCH: 1 1 / 16" end wrench; 6-3 / S" long.
6R574 1 3-2
WRENCH: 7 / 16" socket wrench; Spintite.
Walden
6R574 1 3-4
WRENCH: 1 / 2 " socket wrench; Spintite :
Walden
2 AK 1 3 59-3
* STAYS: l / S " ; 7-sttand wire rope; 43'-6" long; two
thimbles and turn buckle.
Mast guys - (top)
*No longer supplied.
.
tOne stay (black) and one say (orange) is equipped with two turn buckles, one on each end of stay.
Bendix
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CONT. or GOVT.
DWG. or SPEC. No.
*SHA.CKLE : "V" shaped; steel platoo; 5 / 1i'i" dia. ;
screw with eyelet type _head; working length 1 - 1 / 4" .
2 AK3i07· 14. 1
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ANTENNA MAST MA- 7-A
- A 1099 10-2
AL75 1 32 - 1
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2AK 1 3 59-4
2 �K2007A/ R 1
tSTAYS: l / S " ; 7-strand wire rope; 23' long; two thim­
bles and turn buckle.
Mast guys (bottom)
ROPE: Radius; 1 / 2 " ; 3-strand rope; 1 3' long.
Anchor location
SBK 1 S2
ANCHOR: Screw type; 2-7 /S" diameter; 30-3 /4" long.
Mast gUy securing
2AK2007A / C3
COUPLING: Sleeve; plywood tubing;
clamps; without eyebolts .
2AK2007A / C2
'
.COUPLING: Sleeve; plywood
clamps; with eyebolts.
tubing;
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Bendix
AC60330- 1
Bendix
C60357
long;
3
Mast section coupling
Bendix
A 1 74202- 1
24"
long;
3
Mast section coupling and
. strays securing
Bendix
AL74247- 1
Mast guys
Bendix
AL75052-2
Mast guys
Bendix
AL75 1 3 1-4
Mast guys
Bendix
AL75 1 3 1-5
Bendix
AC2 1 65- 1
tOne stay (black) and one stay (orange) is equipped with two turn buckles, one on each e nd of stay.
:j:Supplied with present masts, but not supplied with some previous masts.
.....
AL75 1 32-2
24"
turntSTAYS : l / S " ; 7-strand wire rope; 43'-6" long;
buckle; 1 snap fastener.
tSTAYS: l / S " ; 7-strand wire ·rope; 2 1'-7" long; 2 turnbuckles; 2 snap fasteners.
tSTAYS: 1 /s"·; 7-strand wire rope; 42' long; 2 turnbuckles ; 2 snap fasteners.
tGUY ROPE: Boom yang, 20 ft long.
MODEL:
Bendix
RADIO SET SCR-624-A A N D SCR-62 4 - B
C- 1 0 1
3DB 10-79
CAPACITOR, fixed: dry electrolytic; 1 0 mf; 5 0 vdcw.
C- 102
3DA lO- 3 1 4
CAPACITOR: oil filled in metal can; mfd ± 20% ;
1000 vdcw.
C- 103
3DB20-7S
E- 1 0 1
Boom yang
Audio cathode bypass
MAJOR A S SE MB LY :
LOU DSPEAKER LS- 1 0-A
Industrial Condenser
Type 1-B- 162
Oxford- Tartak P-2 125
Plate blocking
Industrial Condenser
Type SC IOBATO I
Oxford-Tartak P-2 126
CAPACITOR, fixed: dry electrolytic; 475 vdcw.
Screen bypass
Industrial Condenser
Type 40B-269
Oxford-Tartak P-2 124
32 1 0 1 1
CLIP, fuse: 1 amp.
Holds fuse
Littelfuse Type 10 1 1
Oxford-Tartak P-2 1 39
E-101
3Z 1964
FUSE, cartridge:
Line protection
Littelfuse Type 4AG
Oxford-Tartak P-2 I40
E- 102
6Z4S56-S
GROMMET, black rubber: 3/S" center hole, 1 /2 " metal
clearance hole; 5 / S" diam x 1 / 4" thk.
Shock absorber
Atlantic Rubber Type
2 30
Oxford-Tartak P- 1905
E-103
6Z4S5S-3
GROMMET, black robber: 3 / 16" center hole, 5 / 16"
metal clearance hole 1 3 / 32", 7 / 32" thk.
Shock absorber
La Valle Rubber Type
903
Oxford-Tartak P-2 143
GROMMET, black rubber: 5 / 16" center hole, 13 / 32"
metal clearance hole, 5 / S " diam x 1 / 4" thk.
Shock absorber
La Valle Rubber Type
909
Oxford-Tartak P-2 144
E- 104
6Z49 1 3
1
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Referen�e
Symbol
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TABLE OF REPLACEABLE PARTS
SCR-624-A AND SCR-624-B
Army Stock No.
Navy Stock No.
British Ref. No.
NAME OF PART and DESCRIPTION
FUNCTION
MFR. and DESIG.
or
AWS TYPE
3Z2880-8
HOLDER, fuse board assembly: to accommodate 2 No.
P-2 140 fuses; board marked 1 10 v and 220 v.
Holds fuse
E - I 06
2Z582 1-5
KNOB : bar pointer; black bakelite; for 1 /4" shaft.
Volume control
Harty Daview Type
2 1 50
Oxford-Tartak P-2 146
E- I07
2Z5883-235
LAMPHOLDER: less jewel bayonet socket.
Holds lamp
Drake Mfg. 10-G
Oxford-Tartak P-2136
H- l() l
2Z302 1-23
PHONE TIP:
Input connection
American Rodio Hardware 1 6
Oxford-Tartak P-2 1 4 1
H- l02
2Z9049.36
HANDLE,
treated.
1- 1 0 1
2Z5952
LAMP, incandescent: pilot ; bayonet base; 6 to 8 volts.
dark brown sole leather; viscolized
Carrying
Oxford-Tartak G-648
L & N Specialty 333
GE Mazda 47
JACK, telephone: US Army Spec No. 7 1 -852.
2Z5534
IS- 1 0 1
6C37-6
LOUDSPEAKER: 5 " diam, weather proof cone; plated
and painted metal parts.
Oxford-Tartak P- 1488-2
Oxford-Tartak P- 1785
P- 1 0 1
2Z303- 1 7
R- l 0 1
3Z604o- 10
R- 1 02
3Z74 10-2 5
S- 1 0 1
3Z8 1 30
T- I 0 l
2Z9632.36 1
T- l02
2Z9608-5 5
X 1Q l
2Z8678.222
Chicago Telephone
}K-34-A
Oxford-Tartak P-2 1 3 7
Produces sound
Oxford-Tartak PM5-3-4
ADAPTER, plug: 1 10 v AC; receptacle and plug; con-
Power connection
Oxford-Tartak P-2 144
RJ<;SISTOR, fixed : 400 ohms ±
composition.
Audio cathode bias
Stackpole Carbon CM- l
Oxford-Tartak P-2098
Volume control
Chicago Telephone 45
Oxford-Tartak P- 1984
sisting of Amphenol 6 1M plug, 3- 14-D shell and 6 1 F
receptacle with No. P-2 143 grommet.
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J- 1 0 1
20 % , 1
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CONT. or GOVT.
DWG. or SPEC. No.
E- I 0 5
strap:
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MAJOR ASSEMBLY: LOUDSPEAKER LS- l 0-A
insulated
RESISTOR, fix variable: 1 0,000 ohms ± 20 % ; D taper.
SWITCH, toggle: Sig C Switch SW- 1 30; DPST.
TRANSFO RMER: housed in metal can; wax filled pdmary impedance 6000 to 4 ohm load.
TRANSFORMER: 1 17 to 234 v AC; 40 to 60 cycles;
secondary No. 1 , 450 v center tapped, 35 ma; secondary No. 2, 6.30 v, .75 amp. $econdary No. 3, 12.6 v,
. 1 5 amp.
SOCKET, octal: black bakelite; 1 - 1 / 2 " mtg/C.
Opens and closes power line
AH & H 20902-N
Oxford-Tartak P- 1 542
Output transformer
Illinois Transformer
Oxford-Tartak 2D-86-A
Power transformer
Merit Transformer
Corp.
Oxford-Tartak P-200 1
Holds tube
Rohden Mfg. Co.
Oxford-Tartak P-2 1 1 1
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CAPACITOR, fixed : paper dielectric; 1 0,000 mmf. ±
20 % ; 1 ,000 vdcw.
Plate blocking
JAN CN43RI03M
Hallicrafters
CN4 3 R I 0 3 M
CAPACITOR; fixed : Dry electrolytic; 2 section; 20 mfd.
ea.; 450 vdcw.
Audio cathode bypass, and filter
JAN CE32D200R
Hallicrafters 45B 1 40
E- I
HOLDER, fuse : extractor post type; one 3AG cartridge
fuse.
Line protection
Littlefuse 1075
Hallicrafters 6A053
E-2
KNOB, round : black general purpose phenolic; for
.25 3/.255 diam shaft; single 6-32 set screw.
Volume control
Peerless Moulding
Hallicrafters 15A049
Holds lamp
Drake 20
Hallicrafters 86A0 1 6
"
GROMMET, black rubbe r : YI " I.D. x ,", O. D. x YI "
thk; fits %" di,a . chassis hole.
I nsulation
Atlantic Rubber 763
Hallicrafters 1 6A002
x
I nsulation
Atlantic Rubber 2 2 8 1
Hallicrafters 16A0 19
Line protection
Littlefuse 1 040
Hallicrafters 39A306
I nput connection
American Radio
Hardware 1 6
Hallicrafters 10A306
JACK, telephone : Sig C SC-D- 2 3 39; for 2 cond plug.
Headset connection
Mallory SC- l A
Hallicrafters 36A042
LAMP, incandescent : 6-8 V. 1 50 ma; miniature bayonet
base.
Pilot light
Mazda 47
Hallicrafters 39A004
Produces sound
Jensen P5-V
Hallicrafters 85808 1
Power connection
Hubble HB # 1 3 26
Hallicrafters IOA307
Volume control
Chicago Telephone
Supply Co. # 35
Hallicrafters 25B805
Audio cathode bias
JAN RC30BF39 1 K
Hallicrafters
RC30BF39 1K
JAN RC30BFI05K
Hallicrafters
RC30BF I05K
Co l
C-2
3OB20- 1 4
LIGHT, indicato r : with brake lens; 3,4 " diam 'red faceted lens; for bayonet base Mazda 47 bulb, 1 50 mao
6-8 V.; open frame.
E-3
E-4
GROMMET" black rubbe r : %" J.D. x % " 0.0.
1 1 / 3 2 " thk; fits 'Ys " dia chassis hole.
E-5
F- l
H- i
.1 - 1
LM- l
LS- I
P- I
R- l
R-2
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MAJOR ASSEMBLY: LOUDSPEAKER LS- l 0- C
MODEL: RADIO SET SCR-624 -A A N D SCR- 6 2 4 - B
R-3
2Z302 1 - 2 3
FUSE, cartridge : 1 amp.
TERMINAL, lug : pin type; nickel plated brass; fits
cbrdage CO-219.
SPEAKER, magnetic : 6C3 5 - 1 5 . 1 ; 5 " diam cone; PM
field; 3.5 W; voice coil impedance 3.2 ohms .
..
CONNECTOR, male contact : polarized; 2 fiat parallel
blades; I 170 " x 1 9/ 3 2 " x I " Ig less contacts.
RESISTOR, variable : composition; 10,000 ohms
± 1 5 % ; 1/2 W; 3 solder lugs; sliding brush type; Hallicrafters #9 curve, 625 ohms at 3 5 % clockwise rotation, '1000 ohms at 50 % rotation and 2 3 75 ohms at
65 % rotation.
RESISTOR, fixed : composition; 390 ohms ± 1 0 % ; 1 W.
RESISTOR, fixed : composition; 1 meg ± 10 % ; 1 W.
Bleeder
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Reference
Symbol
Army Stock No.
Navy Stock No.
British Ref. No.
SW- l
3 Z9863-22K
SW-2
3Z9863- 1 3D
T- I
2 Z9636. 1 2 8
T-2
2Z96 19-205
X- I
2Z87'95 . 1 2
1.11
TABLE OF REPLAC EABLE PARTS
NAME O F PART and DESCRIPTION
Switch, toggle : DPST; 1 5 / 3 2 " sleeve 19.
SWITCH, toggle : SPST; lj,j " sleeve 19.
TRANSFORMER, AF : plate coupling type; primary
7500 ohms impedance; secondary 3.5 ohms impedance; 0.29 amps; potted metal case, iron core.
TRANSFORMER, powe r : filament and plate type; input 234 V. 40 to 60 cycles AC with tap at 1 1 7 V.;
single ph; 2 output windings; sec. # 1-260 -V. at 35
ma CT; sec. # 2- 1 2 . 5 V. at .75 ma CT; potted; metal
case.
SOCKET, tube : octal; stainless steel mtg plate; two
5 / 3 2 " diam holes on l Y2 " mtg/C.
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A WS TYPE
CONT. or GOVT.
DWG. or SPEC. No.
Opens and closes power line
JAN ST 22-K
Hallicrafters 6OA337
Line voltage switch
JAN ST- 1 3D
Hallicrafters 6OA338
Output transformer
Chicago Transformer
Corp. # 1 3 2 1 5
Hallicrafters 5 5 B 1 1 8
Power transformer
Chicago Transformer
Corp. # 1 32 3 5
Hallicrafters 5 2 C I 7 2
Holds tube
Amphenol MIP-8TM
Hallicrafters 6A200
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8-13-8-14
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Section VIII
Figure 8-8
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Only some equipments have 241-5
Radio Receiver 8C-624-C-Wiring Diagram
8-17-8-18
Section
AN
VIII
Figure 8-1
16-40SCR624-2
------ ---------- -------
NOTES:
F. EQUIPMENT SHOWN IN THE
RECEIVE POSITION ON BAND
"D" WITH SUFFiCIENT INPUT
TO THE RECEIVER TO OPEN
SQUELCH RELAY;
G. VACUUM TUBE NUMBER IN
PAPENTHESIS ARE COMMERCIAL
TYPE NUMBERS.
K. A FEW EQUI PMENTS HAVE ITEMS
105-ll, AND 106.
P. SOME EQUIPMENTSDO NOT HAVE
ITEMS 133-3 AND 133-ll AND
ITEM 152-" IS CONNECTED
BETWEEN Tf � SCREEN GRID OF
THE 2ND HA�. AMP AND
TERMINAL 5 OF ITEM 160.
Referen�e
la
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Modification
Removal of r-f indicator diode.
Painted blad stripe by
position "4."
"METER SWITCH"
Rewiring of oscillator tube JAN-6G6G (VT-198-A) and
speech amplifier tube JAN-6SS7 (VT-199) filament cir­
cuits.
2
Rewiring of squelch circuit.
Painted orange spot on relay 246.
3a
Addition of tube JAN-12H6 noise suppressor and AVC
delay circuit (field modification).
Nameplates
624-A.
3h
Modification of i-f amplifier stages and addition of noise
suppressor and AVC delay (factory modification).
Nameplate
624-AM.
4
Modification of antenna coupling control.
Coupling control on meshed gears instead of
adjustable in slot.
5
Removal of slow release relay l30
modification of contactor circuit.
6
Production of Radio Receiver BC-624-C.
receiver circuit.)
7
Transmitter "GAIN" control 125 replaced by fixed at­
tenuator network (resistors 180 and 181).
from
transmitter;
(Modification
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Note I:. Some models have "gain" control 125,
instead of resistors 180 and 181.
* A few equipments do not have
f,gure 8-4.
101-2, 106, 162-1 Glnd 162-2
Radio Transmitter BC-625-AM-5chemafic Diagram
8 -9-8- 10