9/17/2012
Chapter 5
Amateur Radio Equipment
Generalized Transceiver
Categories
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Single Band
Dual Band
Multimode
Multiband
Handheld (HT)
VHF or UHF FM
VHF/UHF FM
VHF/UHF
HF and VHF/UHF
FM (VHF, UHF, or Both)
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Single Band FM Transceiver
• Probably the most common starter rig.
• Operates from 12 volts dc, requires
external power supply.
• Requires an external antenna.
• Can be operated mobile or as a base
station.
• Usually either 2 meters or 70 cm bands.
• Up to approximately 65 watts output.
Dual Band FM Transceiver
• Same as the single band transceiver but
includes additional band(s).
• Most common are 2 meter and 70 cm
bands.
• Could add 6 meters, 222 MHz or 1.2 GHz.
• Depending on antenna connectors, might
require separate coax for each band or a
duplexer for single coax.
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Multimode Transceiver
• Can be single or multiband.
• Main difference is that these rigs can
operate on all major modes SSB/AM/FM,
CW, Data, RTTY etc.
• More features add complexity and cost.
• Most flexible type of rig. It will allow you
to explore new modes as you gain
experience.
• Best for weak-signal communications.
Multiband HF Transceiver
• Covers many bands – can be limited to
HF or can be HF/VHF/UHF.
• Also covers all modes.
• Frequently 100 watts on HF, some power
limitations on high bands (50 watts).
• Larger units may have internal power
supplies, smaller units need external
power supply (13.8 V).
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Handheld (HT) Transceiver
• Small handheld FM units.
• Can be single band or dual band.
• Limited power (usually 5 watts or less).
• External RF power amplifier.
• Includes power (battery) and antenna in
one package.
• An attractive first starter rig – but make
sure it is what you want.
Rig Vocabulary
• We will now go through some jargon and
vocabulary specific to the functions and
controls of a transmitter and receiver.
• This is a way to discuss how to operate a
transceiver.
• These controls, though separate, are
combined in a transceiver.
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Transmitter Controls & Functions
• Main tuning dial (both TX and RX):
• Controls the frequency selection via the
variable frequency oscillator (VFO).
• Could be an actual dial or key pad or
programmed channels.
• Variable frequency step size (tuning rate,
resolution).
• Could have more than one VFO (control
more that one frequency at a time).
Transmitter Controls & Functions
• Mode selector (both TX and RX for
multimode rigs).
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•
•
Multimode rigs only.
AM/FM/SSB (LSB or USB)
CW
Data (RTTY)
• Could be automatic.
• Based on recognized band plan.
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Transmitter Controls & Functions
• Microphone controls
• Gain
• How loudly you need to talk to be heard.
• Speech Compressor or Speech Processor
• Compacting your speech into a narrow amplitude
range to enhance “punch.”
Transmitter Controls & Functions
• Microphone controls
• Too much gain or compression can cause
problems.
• Over-deviation
• Over-modulation
• Splatter
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Transmitter Controls & Functions
• Automatic Level Control (ALC).
• Automatically limits transmitter drive (output
level) to prevent problems associated with
too much gain or compression.
• Also can control external power amplifier
operation.
Transmitter Controls & Functions
• Transmitter on/off.
• Push-to-Talk (PTT).
• Voice-Operated Transmission (VOX).
• VOX Gain.
• VOX Delay.
• Anti-VOX.
• Key Jack.
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Transmitter Controls & Functions
• Microphones (Mic).
• Hand microphones.
• Desk microphones.
• Preamplified desk microphones.
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Speaker-microphones.
Headsets or boom-sets.
Internal microphones.
Some microphones include PTT & power.
Not all microphones use same connector.
• If same connector, not all wired the same.
Transmitter Controls & Functions
• Morse Keys.
• Straight key.
• Semi-automatic (Bug).
• Electronic keyer and paddle.
• Electronic keyer often built into transceiver.
• Computer keyboard.
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Transmitter Controls & Functions
Transmitter Controls & Functions
• Transmit Meter.
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Output power.
ALC Level.
SWR
Final amplifier stage current.
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Receiver Controls & Functions
• AF Gain or Volume
• Controls the audio level to the speaker or
headphones.
• RF Gain
• Controls the strength of radio signal entering
the receiver.
• Used to limit (attenuate) very strong local
signals.
• Usually operated in the full-open position.
• Not always best practice.
Receiver Controls & Functions
• Automatic Gain Control (AGC)
• Automatically limits the incoming signals
during signal (voice) peaks.
• Prevents peaks from capturing the receiver and
limiting reception of lower level portions of the
incoming signal.
• Fast setting for CW.
• Slow settings for SSB and AM.
• Not used for FM.
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Receiver Controls & Functions
• Squelch.
• Turns off audio to speaker when signal is not
present.
• Open – allows very weak signals to pass through
(along with noise).
• Tight – allows only the strongest signals to pass
through.
• Advance the squelch control until the noise just
disappears.
• Used primarily for FM.
Receiver Controls & Functions
• Filters
• Bandwidth filter
• Used to narrow the width of signal that is passed.
• Can attenuate adjacent interference.
• Notch filter
• Very narrow filter that can be moved over an
interfering signal to attenuate it.
• Noise blanker or limiter
• Limits signal spikes that are frequently associated
with random naturally generated noise.
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Receiver Controls & Functions
• Receiver Incremental Tuning (RIT).
• a.k.a. – Clarifier.
• Used to adjust receiver frequency a small
amount without changing the transmit
frequency.
• A single-sideband signal sounds “funny” if slightly
off frequency.
Receiver Controls & Functions
• Receive Meter.
• Signal strength.
• Measured in “S” units.
• S1 to S9, dB over S9.
• S9 = 1 mV at antenna terminals.
• S9 = -73 dBm.
• 0 dBm = 1 mW into 50Ω load.
• Increase of 1 S-unit = Increase of 6 dB.
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Receiver Controls & Functions
• Receivers can be limited to ham bands or
can cover other parts of the spectrum.
• General coverage receivers cover a wide
area of the spectrum and can be used for
shortwave listening (SWL).
Handheld Transceivers
• Single, dual and multiband versions (with
increasing cost and complexity).
• Some have expanded receiver coverage
(wide-band receive).
• Very portable and self-contained.
• Internal microphone and speaker.
• Rubber duck antenna.
• Battery powered.
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Handheld Transceivers
• Nice to have handheld accessories:
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Extra battery packs.
Drop-in, fast charger.
Extended antenna.
External microphone and speaker.
Headset.
T2B03 - Which of the following describes
the muting of receiver audio controlled
solely by the presence or absence of an RF
signal?
A. Tone squelch
B. Carrier squelch
C. CTCSS
D. Modulated carrier
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T4A01 - Which of the following is true
concerning the microphone connectors on
amateur transceivers?
A. All transceivers use the same microphone
connector type
B. Some connectors include push-to-talk and
voltages for powering the microphone
C. All transceivers using the same connector
type are wired identically
D. Un-keyed connectors allow any
microphone to be connected
T4B01 - What may happen if a transmitter is
operated with the microphone gain set too
high?
A. The output power might be too high
B. The output signal might become distorted
C. The frequency might vary
D. The SWR might increase
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T4B02 - Which of the following can be used
to enter the operating frequency on a
modern transceiver?
A. The keypad or VFO knob
B. The CTCSS or DTMF encoder
C. The Automatic Frequency Control
D. All of these choices are correct
T4B03 - What is the purpose of a squelch
control on a transceiver?
A. To set the highest level of volume desired
B. To set the transmitter power level
C. To adjust the automatic gain control
D. To mute receiver output noise when no
signal is being received
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T4B04 - What is a way to enable quick
access to a favorite frequency on your
transceiver?
A. Enable the CTCSS tones
B. Store the frequency in a memory channel
C. Disable the CTCSS tones
D. Use the scan mode to select the desired
frequency
T4B05 - Which of the following would
reduce ignition interference to a receiver?
A. Change frequency slightly
B. Decrease the squelch setting
C. Turn on the noise blanker
D. Use the RIT control
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T4B07 - What does the term “RIT” mean?
A. Receiver Input Tone
B. Receiver Incremental Tuning
C. Receiver Inverter Test
D. Remote Input Transmitter
T4B08 - What is the advantage of having
multiple receive bandwidth choices on a
multimode transceiver?
A. Permits monitoring several modes at once
B. Permits noise or interference reduction by
selecting a bandwidth matching the mode
C. Increases the number of frequencies that
can be stored in memory
D. Increases the amount of offset between
receive and transmit frequencies
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T4B09 - Which of the following is an
appropriate receive filter to select in order
to minimize noise and interference for SSB
reception?
A. 500 Hz
B. 1000 Hz
C. 2400 Hz
D. 5000 Hz
T4B10 - Which of the following is an
appropriate receive filter to select in order
to minimize noise and interference for CW
reception?
A. 500 Hz
B. 1000 Hz
C. 2400 Hz
D. 5000 Hz
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T7A09 - Which of the following devices is
most useful for VHF weak-signal
communication?
A. A quarter-wave vertical antenna
B. A multi-mode VHF transceiver
C. An omni-directional antenna
D. A mobile VHF FM transceiver
T7A10 - What device increases the lowpower output from a handheld transceiver?
A. A voltage divider
B. An RF power amplifier
C. An impedance network
D. A voltage regulator
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T7B01 - What can you do if you are told
your FM handheld or mobile transceiver is
over deviating?
A. Talk louder into the microphone
B. Let the transceiver cool off
C. Change to a higher power level
D. Talk farther away from the microphone
T8D10 - Which of the following can be used
to transmit CW in the amateur bands?
A. Straight Key
B. Electronic Keyer
C. Computer Keyboard
D. All of these choices are correct
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Data Modes
• a.k.a. – Digital modes.
• Connecting computers via ham radio.
• Some systems use radio to connect to internet
gateways.
• The bulk of the work is done by specialized
modems or computer software/sound card.
• Terminal Node Controller (TNC).
• Multiple Protocol Controller (MPC).
Digital Modes
• Error Correction.
• Bit Error Rate (BER).
• BER = number of bit errors / total number of bits.
• Forward Error Correction (FEC).
• Adds extra information so that data can be
reconstructed. (e.g. - MFSK-16)
• Automatic Repeat Request (ARQ).
• If error detected, asks sending station to
retransmit data. (e.g. - packet radio)
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Popular Digital Modes
• Radioteletype (RTTY)
• PSK31.
• Packet Radio.
• Automatic Packet Reporting System
(APRS).
• Winlink.
• And many, many more….
Automatic Packet Reporting System
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Data Station Setup
Internet Gateway
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T4A06 - Which of the following would be
connected between a transceiver and
computer in a packet radio station?
A. Transmatch
B. Mixer
C. Terminal node controller
D. Antenna
T4A07 - How is the computer’s sound card
used when conducting digital
communications using a computer?
A. The sound card communicates between
the computer CPU and the video display
B. The sound card records the audio
frequency for video display
C. The sound card provides audio to the
microphone input and converts received
audio to digital form
D. All of these choices are correct
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T7B12 - What does the acronym “BER”
mean when applied to digital
communications systems?
A. Baud Enhancement Recovery
B. Baud Error Removal
C. Bit Error Rate
D. Bit Exponent Resource
T8C11 - What name is given to an amateur
radio station that is used to connect other
amateur stations to the Internet?
A. A gateway
B. A repeater
C. A digipeater
D. A beacon
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T8D01 - Which of the following is an
example of a digital communications
method?
A. Packet
B. PSK31
C. MFSK
D. All of these choices are correct
T8D02 - What does the term APRS mean?
A. Automatic Position Reporting System
B. Associated Public Radio System
C. Auto Planning Radio Set-up
D. Advanced Polar Radio System
NOTE: This is an error in the question pool.
The correct answer should read:
“Automatic Packet Reporting System”.
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T8D02 - What does the term APRS mean?
A. Automatic Position Reporting System
B. Associated Public Radio System
C. Auto Planning Radio Set-up
D. Advanced Polar Radio System
NOTE: This is an error in the question pool.
The correct answer should read:
“Automatic Packet Reporting System”.
T8D03 - Which of the following is normally
used when sending automatic location
reports via amateur radio?
A. A connection to the vehicle speedometer
B. A WWV receiver
C. A connection to a broadcast FM subcarrier receiver
D. A Global Positioning System receiver
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T8D06 - What does the abbreviation PSK
mean?
A. Pulse Shift Keying
B. Phase Shift Keying
C. Packet Short Keying
D. Phased Slide Keying
T8D07 - What is PSK31?
A. A high-rate data transmission mode
B. A method of reducing noise interference
to FM signals
C. A method of compressing digital television
signal
D. A low-rate data transmission mode
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T8D08 - Which of the following may be
included in packet transmissions?
A. A check sum which permits error
corrections
B. A header which contains the call sign of
the station to which the information is
being sent
C. Automatic repeat request in case of error
D. All of these choices are correct
T8D09 - What code is used when sending
CW in the amateur bands?
A. Baudot
B. Hamming
C. International Morse
D. Gray
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T8D11 - What is a “parity” bit?
A. A control code required for automatic
position reporting
B. A timing bit used to ensure equal sharing
of a frequency
C. An extra code element used to detect
errors in received data
D. A “triple width” bit used to signal the end
of a character
Break
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Power Supplies
• House power is ~120 VAC, 60 Hz.
• Most modern radios require ~12 VDC.
• Actually 13.8 VDC.
• A power supply is a device that converts
120 VAC power to the desired DC
voltage or voltages.
Power Supplies
• Unregulated supply.
• Simple circuit.
• Voltage can vary over a wide range with
changing load current.
• Regulated supply.
• More complex circuit.
• Voltage is nearly constant with changing load.
• Modern rigs work best with a regulated
power supply.
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Power Supplies
• Regulated Power Supplies.
• Linear.
• Large & heavy.
• Inefficient.
• Generate heat.
• Easy to repair.
• Less expensive.
Power Supplies
• Regulated Power Supplies.
• Switching.
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Small & lightweight.
Very efficient.
More difficult to repair.
More expensive.
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Power Supplies
• Ratings:
• Continuous current.
• How much current can be supplied over the
long term.
• Intermittent current.
• How much surge current can be supplied over
the short term.
• Voltage regulation.
• How well the power supply can handle rapid
current changes.
Mobile Power Wiring
• Fuse BOTH positive & negative leads
close to the power connection.
• Connect negative lead to battery or to
battery ground connection.
• Use grommets or sleeves to protect
wires where they pass through firewall.
• Do NOT assume that all metal body
parts are grounded.
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Mobile Power Wiring
• Mobile installations can suffer from noise
from the vehicle electrical system.
• Receive Interference.
• Ignition noise.
•
Regular noise pulses when spark plugs fire.
• Alternator whine.
•
High-pitched whine that varies in frequency with
engine speed.
• Transmit Interference.
• Alternator whine.
Generators & Inverters
• For emergency & portable operations,
commercial AC power may not be
available.
• Generator.
• Converts mechanical energy to electrical
energy.
• Inverter.
• Converts DC voltage to AC voltage.
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Generators & Inverters
• For emergency & portable operations,
commercial AC power may not be
available.
• Generator.
• Converts mechanical energy to AC or DC
electrical energy.
• Inverter.
• Converts DC voltage to AC voltage.
Generators & Inverters
• Motor-Generator Sets.
• AC generator connected to small gasoline
engine.
• Old technology.
• Less Expensive.
• Typically very noisy.
• Output voltage not pure sine wave.
• Distorted output may damage sensitive
electronic equipment.
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Generators & Inverters
• Motor-Generator-Inverter Sets.
• DC generator connected to small gasoline
engine & DC voltage fed to an inverter.
• New technology.
• More expensive.
• Relatively quiet.
• Output voltage is pure sine wave.
• Safe for sensitive electronic equipment.
Generators & Inverters
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T4A03 - Which is a good reason to use a
regulated power supply for
communications equipment?
A. It prevents voltage fluctuations from
reaching sensitive circuits
B. A regulated power supply has FCC
approval
C. A fuse or circuit breaker regulates the
power
D. Power consumption is independent of
load
T4A03 - Which is a good reason to use a
regulated power supply for
communications equipment?
A. It prevents voltage fluctuations from
reaching sensitive circuits
B. A regulated power supply has FCC
approval
C. A fuse or circuit breaker regulates the
power
D. Power consumption is independent of
load
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T4A10 - What is the source of a highpitched whine that varies with engine speed
in a mobile transceiver’s receive audio?
A. The ignition system
B. The alternator
C. The electric fuel pump
D. Anti-lock braking system controllers
T4A11 - Where should a mobile
transceiver’s power negative connection be
made?
A. At the battery or engine block ground
strap
B. At the antenna mount
C. To any metal part of the vehicle
D. Through the transceiver’s mounting
bracket
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T5A06 - How much voltage does a mobile
transceiver usually require?
A. About 12 volts
B. About 30 volts
C. About 120 volts
D. About 240 volts
T6D05 - What type of circuit controls the
amount of voltage from a power supply?
A. Regulator
B. Oscillator
C. Filter
D. Phase inverter
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T7B09 - What could be happening if another
operator reports a variable high-pitched
whine on the audio from your mobile
transmitter?
A. Your microphone is picking up noise from
an open window
B. You have the volume on your receiver set
too high
C. You need to adjust your squelch control
D. Noise on the vehicle’s electrical system is
being transmitted along with your speech
audio
Batteries
• Create electrical energy through a
chemical reaction.
• Primary cell.
• Chemical reaction is not reversible.
• Cannot be recharged.
• Secondary cell.
• Chemical reaction is reversible.
• Can be recharged.
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Batteries
• Cell voltage depends on chemicals used.
• Capacity rated in Ampere-hours (AH) or
milliampere hours (mAH).
• 500 mAH battery will provide:
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500 mA for 1 hour.
50 mA for 10 hours.
25 mA for 20 hours.
5 mA for 100 hours.
etc.
Batteries
• Lead-Acid.
• Secondary cell.
• Approximately 2.12 Volts per cell.
• “12V” battery = 6 cells in series.
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•
•
Open-Circuit at full charge: 12.6 V to 12.8 V
Open-circuit at full discharge: 11.8 V to 12.0 V
Loaded at full discharge: 10.5 V
Float Charge: 13.8 V
Daily Charge: 14.2 V to 14.5 V
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Batteries
• Lead-Acid.
• If overcharged will release hydrogen gas.
• Remember the Hindenberg!
• ALWAYS use in well-ventilated area!
• Gassing threshold ~14.4 V.
Batteries
• Gel-Cell.
• a.k.a. – Sealed lead-acid (SLA).
• Electrolyte is in a gel form rather then liquid.
• Sealed so does not vent hydrogen gas.
• Avoid over charging to prevent build up of
internal pressure.
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Other Types of Batteries
Chemistry
Carbon-Zinc
(obsolete)
Alkaline
Cell Voltage
1.5V
Type
Disposable
1.5V
Disposable*
Nickel-Cadmium
(NiCad)
1.2V
Rechargeable
Nickel-Metal-Hydride
(NiMH)
Lithium Ion
(LI-Ion)
1.2V
Rechargeable
3.6V
Rechargeable
Battery Charging
• Some batteries can be recharged, some
cannot.
• Use the proper charger for the battery
being charged.
• Batteries will wear out over time.
• Best if batteries are maintained fully
charged.
• Over-charging will cause heating and could
damage the battery.
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Handheld Transceiver Batteries
• Battery packs – packages of several
individual rechargeable batteries
connected together.
• NiCd (nickel-cadmium).
• NiMH (nickel-metal hydride).
• Li-ion (lithium-ion).
• For emergencies, have a battery pack
that can use disposable batteries (usually
AA size).
T6A10 - What is the nominal voltage of a
fully charged nickel-cadmium cell?
A. 1.0 volts
B. 1.2 volts
C. 1.5 volts
D. 2.2 volts
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T6A11 - Which battery type is not
rechargeable?
A. Nickel-cadmium
B. Carbon-zinc
C. Lead-acid
D. Lithium-ion
T0A08 - What is one way to recharge a 12volt lead-acid station battery if the
commercial power is out?
A. Cool the battery in ice for several hours
B. Add acid to the battery
C. Connect the battery to a car’s battery and
run the engine
D. All of these choices are correct
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T0A09 - What kind of hazard is presented by
a conventional 12-volt storage battery?
A. It emits ozone which can be harmful to the
atmosphere
B. Shock hazard due to high voltage
C. Explosive gas can collect if not properly
vented
D. All of these choices are correct
T0A10 - What can happen if a lead-acid
storage battery is charged or discharged
too quickly?
A. The battery could overheat and give off
flammable gas or explode
B. The voltage can become reversed
C. The “memory effect” will reduce the
capacity of the battery
D. All of these choices are correct
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Radio Frequency Interference (RFI)
• Radio frequency signals (RF) causing
interference with the proper operation of
an electronic device.
• Your transmitted signal can interfere with
electronic devices, even if it is operating
properly.
• Radio frequency signals generated by
electrical devices can interfere with your
receiver.
Radio Frequency Interference (RFI)
• Filters.
• Used to prevent interfering signals from
entering a piece of equipment.
• High-Pass -- Passes frequencies above a
frequency.
• Low-Pass -- Passes frequencies below a
frequency.
• Band-Pass -- Passes frequencies within a
frequency range.
• Band-Reject -- Passes frequencies outside of a
frequency range.
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Radio Frequency Interference (RFI)
• RF choke.
• a.k.a. – Common-mode choke.
• a.k.a. – Ferrite choke.
• Special type magnetic material (ferrite)
placed around a conductor or cable.
• The “lump” in computer cables.
• Prevents RF from entering or leaving a piece
of electronic equipment via the cable.
Radio Frequency Interference (RFI)
• Ferrite choke.
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Types of RFI
• Direct detection.
• The presence of a strong RF signal can
interference with an electronic device even if
the transmitter is operating properly.
• Often caused by the device acting as a
receiver even when it is not designed to.
• Semiconductors in the device can act as
diode detectors.
• This is called direct detection.
Types of RFI
• Direct detection.
• Telephones.
• Direct detection is most common type of RFI.
• Low-pass filter at telephone wall jack.
• Ferrite choke on telephone cord.
• Stereos.
• Touch-activated lamps.
• Electronic doorbells.
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Types of RFI
• Overload.
• Very strong off-frequency signals can
overwhelm the input stages of a receiver.
• Interfering signal may be heard regardless of
frequency (channel) receiver is tuned to.
• Problem lies within the receiver.
• Add filters to receiver input.
•
e.g. – Add band-reject (notch) filter to prevent a 2-meter
signal from interfering with broadcast TV.
• Adding filters to transmitter will not help.
Types of RFI
• Harmonics & Spurious Emissions.
• All transmitted signals contain harmonics and
other spurious emissions (spurs).
• Goal is to reduce strength of harmonics &
spursas much as possible.
•
•
Good transmitter design.
Proper operation.
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Types of RFI
• Harmonics & Spurious Emissions.
• Problem lies within the transmitter.
• Install low-pass filter or band-pass filter between
transmitter and antenna to reduce harmonics.
• Filtering may not reduce strength of spurious
emissions (non-harmonic) if close to transmitter
frequency.
• Adding filters to receiver input will not help.
Types of RFI
• Cable TV Interference
• Usually the result of broken shielding
somewhere in the cable.
• Loose connections.
• Broken connections.
• Corroded connections.
• Usually solved by proper cable maintenance
by cable supplier.
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Types of RFI
• Noise Sources.
• Most interference to amateur radio receivers
is not from transmitters, but from
“unintentional radiators”.
• Electrical arcs (motors, thermostats, electric
fences, neon signs, etc.).
• Power lines.
• Motor vehicle ignitions or alternators.
• Switching power supplies.
• Computers, networks, and TV sets.
Types of RFI
• Intermodulation.
• Two signals combine (mix) to produce an
interfering signal.
• Find circuit where mixing is occurring.
• Add filter(s) to eliminate one or both of the signals
being mixed.
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Dealing with RFI
• Make sure you operate your equipment
properly.
• Eliminate interference in your own home
first.
Dealing with RFI
• Take interference complaints seriously.
• Make sure that you’re really not the cause.
• Demonstrate that you don’t interfere within
your own home.
• Offer to help eliminate the RFI, even if you
are not at fault.
• Consult ARRL RFI Resources for help and
assistance.
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What the Rules Say
• RFI from and to unlicensed devices is the
responsibility of the users of such devices.
• Bottom line – If your station is operating
properly, you are protected against
interference complaints.
• BUT – Be a good neighbor because they
may (probably) not be familiar with Part 15
rules and regulations.
T4A04 - Where must a filter be installed to
reduce harmonic emissions?
A. Between the transmitter and the antenna
B. Between the receiver and the transmitter
C. At the station power supply
D. At the microphone
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T4A05 - What type of filter should be
connected to a TV receiver as the first step
in trying to prevent RF overload from a
nearby 2 meter transmitter?
A. Low-pass filter
B. High-pass filter
C. Band-pass filter
D. Band-reject filter
T4A09 - Which would you use to reduce RF
current flowing on the shield of an audio
cable?
A. Band-pass filter
B. Low-pass filter
C. Preamplifier
D. Ferrite choke
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T7B04 - What is the most likely cause of
interference to a non-cordless telephone
from a nearby transmitter?
A. Harmonics from the transmitter
B. The telephone is inadvertently acting as a
radio receiver
C. Poor station grounding
D. Improper transmitter adjustment
T7B05 - What is a logical first step when
attempting to cure a radio frequency
interference problem in a nearby
telephone?
A. Install a low-pass filter at the transmitter
B. Install a high-pass filter at the transmitter
C. Install an RF filter at the telephone
D. Improve station grounding
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T7B06 - What should you do first if
someone tells you that your station’s
transmissions are interfering with their
radio or TV reception?
A. Make sure that your station is functioning
properly and that it does not cause
interference to your own television
B. Immediately turn off your transmitter and
contact the nearest FCC office for assistance
C. Tell them that your license gives you the right
to transmit and nothing can be done to
reduce the interference
D. Continue operating normally because your
equipment cannot possibly cause any
interference
T7B07 - Which of the following may be
useful in correcting a radio frequency
interference problem?
A. Snap-on ferrite chokes
B. Low-pass and high-pass filters
C. Band-reject and band-pass filters
D. All of these choices are correct
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T7B08 - What should you do if a “Part 15”
device in your neighbor’s home is causing
harmful interference to your amateur
station?
A. Work with you neighbor to identify the
offending device
B. Politely inform your neighbor about the rules
that require him to stop using the device if it
causes interference
C. Check your station and make sure it meets
the standards of good amateur practice
D. All of these choices are correct
Electrical Grounding
• Make sure your home is “up to code.”
• Most ham equipment does not require
special wiring or circuits.
• Use 3-wire power cords.
• Use circuit breakers, circuit breaker outlets, or
Ground Fault Interrupter (GFI) circuit breakers.
• Use proper fuse or circuit breaker size.
• Don’t overload single outlets.
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RF Grounding
• Amateur radio stations require a separate
“RF” ground.
• Lack of a proper RF ground can result in:
• RF burns when touching equipment while
transmitting.
• RF feedback resulting in distorted audio on
transmitted signal.
• Erratic operation of computer equipment.
RF Grounding
• All equipment should be connected to a
common ground.
• Ground should be as short as possible.
• Use wide, flat copper strap or braid.
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Lightning Protection
• Install a separate ground
rod by each leg of your
tower.
• Do NOT run ground rods
through concrete base.
• Ground rods should be
bonded to the tower leg &
to each other.
• Connect to station ground.
T7B11 - What is a symptom of RF feedback
in a transmitter or transceiver?
A. Excessive SWR at the antenna
connection
B. The transmitter will not stay on the
desired frequency
C. Reports of garbled, distorted, or
unintelligible transmissions
D. Frequent blowing of power supply fuses
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T4A08 - What type of conductor is best to
use for RF grounding?
A. Round stranded wire
B. Round copper-clad steel wire
C. Twisted-pair cable
D. Flat strap
Questions?
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Next Session
Chapter 7
Licensing Regulations
Chapter 8
Operating Regulations
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