QUA
QUA
October 2015 Oktober
ZT/FS-005 Hano
Nasionale Velddag, 12 en 13 September
Page 1
Bloemfontein Amateur Radio Club
Bloemfontein Amateurradioklub
QUA
October 2015 Oktober
Bloemfontein Amateur Radio Club
Bloemfontein Amateurradioklub
Bloemfontein Branch of the SARL - 1 July 1980 - 30 June 1996
Bloemfontein Amateur Radio Club - 1 July 1996 to
olunteers are important. 1. Why do you want to get inHowever, more important volved? Is it because you have the
are the reasons for volun- time and talents, or is it for the frateering and the way an ternity and recognition? Can you
organization is managed to make it serve a productive, required need?
effective.
2. We all have busy lives. Even
The key point is that things just retirees have full schedules. Are
do not happen in a club or organi- you able to volunteer, or are you
sation. It takes people to be the are already over-committed? How
soldiers of any organisation. Volun- much can you shoulder realisticalteers know the capabilities, re- ly?
sources and how to get things 3. Are your talents needed? Is
done! They are the link.
there something you want to do?
Volunteering is an important This is an important question beand essential contribution to socie- cause it focuses on your investty. Without volunteers, many of the ment in the group's mission.
tasks we face in life would be com- 4. Do you have the ability to perpromised. Just think about the form the volunteer activities for
neighbourhood watch or in Afri- which you are expected to perkaans, die buurtwag. Along our form? Ask yourself the simple
coasts we have the National Sea question, can I do what is asked of
Rescue Institute (NSRI) who are all me?
volunteers.
5. Are your efforts competing with
But, you cannot take volunteer- other volunteer and hobby posiing lightly. Before pledging yourself tions?
to an club/organisation, analyse all 6. Are you physically able to volthe reasons and your abilities. You unteer? There are certain stages in
should get involved if you can per- your life when volunteering may
form a service. You should not vol- not be a good option.
unteer if you do not have commit- 7. Do you have the right equipment, ability, or preconceived no- ment and resources to perform
tions how the club/organization what is asked of you?
should be run.
8. Are you joining because of peer
Bad volunteers cause problems pressure? Sometime our friends
within a club/organisation, as well are our own worse enemy.
as personal and professional credi- 9. Are you joining because of
bility issues. Most of all, they let sympathy? Believe it or not, many
down their club or organisation.
(Continued on page 16)
V
Klub Bulletins
Maandag 19:30 op
145,600 MHz FM via die
Naval Hill herhaler
Club Meetings
First Saturday of each
month at 14:00 (winter)
or 16:00 (summer) at
the Club House at CBC
School
Club meeting 16:00 on Saturday 3 October 2015
Klubvergadering 16:00 op
Saterdag 3 Oktober 2015
More information in the Club
bulletin on Monday evenings
at 19:30 on 145,600 MHz FM
Meer inligting in die Klubbulletin op Maandae-aande om
19:30 op 145,600 MHz FM
www.zs4bfn.co.za
https://www.facebook.com/
groups/zs4bfn/
Repeaters and Beacons
145,600 MHz FM Naval
Hill
145,650 MHz FM Brandkop
145,700 MHz FM Springfontein
ZS4AFV Beacon
144,415 MHz CW
5 290 kHz WSPR
Disclaimer. The Editor nor any club member shall not be held liable for errors and/or omissions in any article and/or drawing contained in this
newsletter. Furthermore, any view expressed is not necessarily that of the Editor, any committee member or other members of the Club. If copyright is infringed, it is not intentional but, is published as a free service to Amateur Radio operators and friends and is not for profit or gain.
Page 2
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October 2015 Oktober
Build a Space-Efficient Dipole Antenna
for 40, 80 and 160 Metres
A. C. Buxton, W8NX
A new trap design, using only RG-58 and PVC pipe,
yields better space efficiency than conventional coaxial traps.
T
hese days more than ever before,
many radio amateurs who want to
work the low bands need an effective
antenna that fits on a small lot. I will
show you how to build a shortened dipole for
160, 80 and 40 metres using improved coaxialcable traps that I call Super Traps. The antenna, which covers the three amateur bands below 7,3 MHz, is about the same length as a fullsize 80-metre dipole. If you install the antenna
as an inverted V with a 90° included angle, the
baseline length is 88 feet (26,8 m). The antenna uses traps that are easily constructed, rugged and weatherproof. They use no exposed
capacitors or inductors.
You can feed the antenna directly with balanced 75 Ω line or via a 1:1 balun with either
50 or 75 Ω coaxial cable. Feed-line length is
not critical. The antenna resonates at 1,865,
3,825 and 7,225 MHZ. l installed such an antenna on my lot as an inverted V, with the apex
38 feet (11,5 m) high and the ends at about 15
feet (4,5 m).
As part of this project, I developed a BASIC
-language computer program for trap design; a
listing is available from the ARRL? You can
use this program to design these traps for frequencies of your choice, but you do not need a
computer to make the antenna described here.
Fig 1 shows the antenna layout. The antenna is
made of #14 stranded wire and 2 pairs of coaxial traps. Construction is conventional in most
respects, except for the high inductance-tocapacitance (L/C) ratio that results from the
unique trap construction. Two recent QST arti-
cles give tips on dipole construction and feeding.
The traps use two-layer windings of the
core (dielectric and centre conductor) of RG-58
coaxial cable. Coaxial cable with flexible, rugged stranded-wire centre conductors is preferable to that with a more brittle solid-wire centre
conductor. Fig 2 shows the traps. The 3,8 MHz
trap is shown with the weatherproofing cover of
electrical tape removed to show the construction details.
Precautions and Trap Specifications
With this trap-winding configuration, there
are two thicknesses of core dielectric material
between adjacent turns, which doubles the
breakdown voltage of the traps. The transformer action of the two windings gives a second
doubling of the trap-voltage rating. Thus, the
trap voltage rating is 5,6 kV (four times RG58's 1,4 kV rating). Conventional coaxial-cable
traps made of RG-58 have a rating of 2,8 kV.
The 7 MHz traps have 33 μH of inductance
and 15 pF of capacitance and the 3,8 MHz
traps have 74 μH of inductance and 24 pF of
capacitance. The trap Qs are over 170 at their
design frequencies, as measured on a Boonton
Q meter.
These traps are suitable for operation at the
1 kW power level. When making the traps, do
not use RG-8X or any other foam-dielectric cable. Winding such cables on small-diameter
forms cause the centre conductor to migrate
through the dielectric toward the inside, de(Continued to page 4)
Fig 1. The shortened dipole resonates in the SSB portions of the 40, 80 and 160-metre bands. The antenna is 124 feet (37,8 m) long.
Page 3
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October 2015 Oktober
(Lithium Polymer Batteries for Amateur Radio from page 3)
creasing the breakdown rating and
compromising trap performance. The
core diameter also differs from that of
RG-58.
Construction
Although these traps are similar in
many ways to other coaxial-cable
traps, the shield winding of the common coax-cable trap has been replaced by an outer winding that fits
snugly into the grooves formed by the
inner layer. Capacitance is reduced to
7.1 pF per foot (30,48 cm), compared to 28.5
pF per foot (30,48 cm) with conventional coax
traps made from RG-58. Trap reactance can
be up to four times greater than that provided
by conventional coax-cable traps.
The coil forms are cut from PVC pipe available at plumbing-supply stores. The 7 MHz trap
form is made from 2 inch (5 cm) ID pipe with an
outer diameter of 2.375 inches (6,0325 cm).
The 3,8 MHz trap form is made from 3 inch
(7,62 cm)pipe with an outer diameter of 3,5
inches (8,89 cm). The 7 MHZ trap uses a 12,3
turn inner winding and an 11,4 turn outer winding. The 3,8 MHz trap uses a 14,3 turn inner
winding and a 13,4 turn outer winding. All turns
are close wound. The inner-trap frequency is
7,17 MHZ and the outer-trap frequency is 3,85
MHz.
If you are unable to get PVC forms of exactly the same diameters as those called for here,
compensate for the effect of form-size differences by taking advantage of the fact that the
number of turns varies inversely with the form
diameter. Thus, if the form diameter you use is,
say, 5% larger than mine reduce the number of
turns by 5%. If necessary, add or remove fractions of a turn at the end of the outer winding. If
you have a computer, you can use the BASIC
program to calculate the exact number of turns
for other form diameters. Stay as close as you
can to the prescribed diameters because too
much deviation changes the loading effect of
the traps. A small change in trap loading may
require a change in the lengths of the tip segments beyond the traps.
Use a #30 (0,128 inch [3.2512 mm] diameter) drill for the feed-through holes in the PVC
coil forms. The start and end holes of the 7
MHz traps are spaced 1,44 inches (3.6576 cm)
Page 4
Fig 2. The improved coaxial cable traps use two layered windings to provide an unusually high inductance-to-capacitance ratio, higher Q and twice the
breakdown voltage of single layer traps. The 3,8
MHz trap is shown without its protective electricaltape wrap to show the details of trap construction.
This construction method makes for simple, lightweight, rugged and weatherproof traps.
centre to centre, measured parallel to the trap
centre line. The holes in the 3,8 MHz traps are
1,66 inches (4.2164 cm) apart. Wind the traps
with a single length of coax core. The unspliced
lengths are 17,55 feet (5,34924 m) for the 7
MHz traps and 28,45 feet (8,67156 m) for the
3,8 MHz traps. These lengths include the trap
pigtails and a few inches for fine-tuning.
Strip the jacket from the coax. This is easily
done using a wood vice with wide jaws to hold
the cable while cutting the jacket longitudinally
with a sharp knife or razor. The coax outer conductor (braid) is best removed by pushing (not
pulling) it off.
Use electrical tape to keep the turns of the
inner-layer winding closely spaced during the
winding process. This counter-acts the tendency of the tension in the outer-layer winding to
spread the inner-layer turns. Stick the tape
strips directly to the coil form before winding
and then tightly loop them over and around the
inner layer before winding the outer layer. Use
six or more tape strips for each trap.
If possible, check the resonant frequencies
of your traps with a dip meter. Try to maintain
an accuracy of 50 kHz or better.
For low-noise reception, erect the antenna
as close to horizontal as possible. lf you let the
ends of the antenna droop toward the ground,
as I have done with my inverted-V installation,
(Continued to page 5)
QUA
October 2015 Oktober
(Lithium Polymer Batteries for Amateur Radio from page 4)
you may have to accept a somewhat higher
noise level in the interest of structural simplicity
and reduced baseline length. Some feel that
the inverted-V configuration is better for DXing
than a horizontal dipole at the same height. For
an inverted V with a 90° included angle (legs
that slope downward at 45 °), you will need a
minimum apex height of about 55 feet (16,764
m) and a baseline length of 88 feet (26,8224
m). Get the apex as high as you can and keep
the ends at least 10 feet (3,048 m) above the
ground for safety.
Configuration and Performance Trade-Offs
You seldom get something for nothing. This
antenna proves no exception to that rule. As
with all trap dipoles, this one has less-thanideal bandwidth due to the loading effect of the
traps. This is the price paid for multiband coverage and physical shortening. This antenna
covers 65 kHz of 160 metres, 75 kHz of 80 metres and the entire 40 metre band with SWRs
under 2:1. The bandwidth limitations on 160
and 80 metres can be largely offset with an antenna tuner.
It is also important to recognize that the
traps are used in low-current portions of the
antenna, minimizing FR trap losses. A relatively high radiation resistance is therefore also retained.
Good luck with your low-band antennas!
Notes
1
I wrote the program in GWBASIC 3.2. It uses
generic BASlC commands and can be easily
converted for use with computers other than
IBM PCs and compatibles.
2
For a copy of the BASIC program, send a
business-size SASE to the ARRL Technical
Department Secretary. 225 Main St, Newington. CT 06111-1494. Request the July 1992
QST BUXTON BASIC PROGRAM listing.
3
JJ. Healy, “Antenna Here is a Dipole,” QST,
Jun 1991, pp 23 to 26.
4
JJ. Healy, “Feeding Dipole Antennas,” QST,
Jul 1991, pp 22 to 24.
5
See note 2.
ZT/FS-005 Hano - Global Mountain Award
Dennis, ZS4BS
aar is SOTA of “Summits on the Air”
en GMA of “Global Mountain Award”
om jou besig te hou. SOTA se vereistes vir ‘n piek is baie streng en dit
is ‘n proses om ‘n piek geregistreer te kry.
GMA sê enige piek 100 m bokant seespieël
kwalifiseer en die registrasie proses is heel
maklik.
In verlede week, so by 24 September se
kant, besluit ek dat Saterdag moet daar bietjie
draagbare amateur radio gespeel word. Naval
Hill is op SOTA (ZS/FS-018) maar ek het te
veel al van daar gewerk. Leeuwberg, suid van
die stad, is op die voorlopige SOTA lys, nog nie terdag.
op die GMA lys nie, MAAR op wie se grond
Saterdagoggend is die logstaat en n waterstaan hy? Moet eers toestemming kry!
bottel in die rugsak gesit en ek ry na die parHier in Langenhovenpark is vier kopjes - die keer area. Een van die dames in die
bekend Spitskop daar naby die N1, dan “Hano” aangrensende meenthuise gooi mielies uit vir
naby die NG Kerk en twee kopjes naby aan die die tarentale. Rugsak op die rug en die mas in
Boeremark. Die een naby die kerk is die tuiste my hand begin ek klim, so derde op, gly my
van n geocache ‘Hano’ en die klim is nie te erg voet en ek rol so ent af! Gelukkig niks
nie.
beserings of toerusting beskadig nie. Verder
Ek het toe Hano gaan registreer op die
geklim tot bo en toe eers gerus - nie so
GMA webwerf en die radio, battery, mas
fiks nie!
en antenna in die rugsak gepak vir Sa(Continued on page 6)
D
Page 5
QUA
October 2015 Oktober
(20 m Ground Plane from page 5)
Die antenna is aan die mas vasgemaak en
opgestoot en die mas is teen die kruis staan
gemaak met bungee-toue. Die FT-817 radio,
Z100 instemmer en battery is gekoppel en
aangeskakel.
Toe roep ek “CQ 40 meter” en Christi,
ZS4CGR is eerste in die logboek gevolg deur
Simon, ZS6SLP en Harold, ZS5CAR. Ek het
ook ’n kontak met Pieter, V51PJ, gemaak beide QRP krag!
SOTA ZS/KN-049, The Sphinx, was ook op
die lug en ek het kontak met Sid, ZS5AYC, Adele, ZS5APT, Magda, ZS6MMS en Lucas,
ZS6ACT, daar gemaak. Ek het met Martin,
ZS4MS, gesels op 145,500 MHz FM. Die
laaste kontak was met Rudi, ZS6DX. Toe is alles opgepak en die paadjie onder toe is
geneem.
Die LHP Boeremark op die voorgrond met Makro se
dak wat in die middle uitsteek. Regs agter is Brandkop en agter in die middle is Leeuwberg.
Die NG Kerk se dak daar onder met die
ongenaamde kopje in LHP. Daar heel agter is
Kloofeind
Spitzkop en sy selfoon torings en twee-rigting radio
torings
Naval Hill vanaf Hano. Hier op die linkerkant is die
Pick&Pay sentrum en die Checkers sentrum in LHP
Page 6
QUA
V
October 2015 Oktober
Nasionale Velddag, 12 en 13 September
ir die tweede been van
die
2015
Nasionale
Velddag was die idee om
na Malealea in Lesotho te
gaan, maar ons planne het nie
uitgewerk nie.
Brendon, ZS4BM, het toe met
die mense van Tuff-Top Estates
gesels en daar is n bespreking gemaak vir die Velddag naweek. Tuff
-Top is daar naby die oorspronklike “Roses for U” langs die Renosterspruit (geen renosters gesien
nie!)
Vrydagmiddag is die karavaan gehaak en
ek en Carina is deur die stad en verby die
lughawe na Tuff-Top. Brendon and Frans Kruger was reeds daar en hulle verbly opgeslaan.
Ons het n plekkie gekry vir ons karavaan en afgehaak. Later het Warren, ZS4W, met sy karavaan opgedaag en toe het Frans, ZS4FM en
Francis, ZS4AM, aangesluit. Vinnig is hulle tent
op en alles ingepak. Ons het gesellig gekuier
om die braaivleis vuur.
Saterdagoggend is die gazebo opgeslaan
vir die foon stasie, die teleskopiese mas is teen
die sleepwa vasgemaak met die 40 en 80 antenna bo vasgemaak. Dis ‘n antenna met sperspoele.
Die digitale stasie in onder die karavaan se
‘rally tent’ opgestel met die 3 band L-antenna
ZS4BFN/p
gekoppel en die Buddipole op 'n gereedheidsgrondslag.
12:00 het aangebreek en daar is begin met
“CQ Field Day” roep. Stadig het die kontakte
ingekom. Warren, ZS4W, het die ESB stasie
hanteer - die algemene gevoel was dat hy die
beste stem vir die taak het! Teen Sondag 12:00
uur was daar 54 kontakte met Suid-Afrikaanse
stasies - agt van die nege provinsies gewerk,
ons kon met nie Limpopo werk nie. En
3DAONJ is ook gewerk. Drie kontakte op 160
m, tien op 80 meter, agt en dertig op 40 m en 4
op twintig meter.
Dennis, ZS4BS, het die PSK hanteer, maar
band toestande was nie wat wonders nie.
Slegs vier kontakte is gemaak, almal op 15 meter - LU1WI, 5R8FL, FR5HA en YU7NW.
Deur die loop van Saterdagmiddag het Michael, ZS4BHF, Hennie, ZS4HG en Neil,
ZS4NN, kom besoek aflê.
Moeder Natuur het ook elke nou en dan ‘n
(Continued to page 8)
Die koppelpunt vir die 20, 15 en 10 m L-antenna
Page 7
QUA
October 2015 Oktober
(20 m Ground Plane from page 7)
buitjie reën gestuur en hier teen 7 uur se kant
was daar blitse en donderweer. Die antennas
is ontkoppel en ons het besluit om te braai.
Aandete is weer daar om die braaivleis vuur
genuttig en daar is lekker gesels.
Sondagoggend is die laaste klompie kontakte gemaak met die digitale kant doodstil.
Carina en mej Marais, die dogter van Frans en
Francis. Sy het ook kom uitkamp en dit baie geniet.
Van die antennas by ZS4BFN/p. Hier voor is die
Buddipole en agter is die mas vir die 20, 15 en 10 m
L-antenna
Baie dankie aan almal wat kom uitkamp
het, wat kom besoek aflê het en die wat met
ons kontak gemaak het. Dit word waardeer.
Birthdays, Anniversaries and other events
1 - Liana van Lill, vrou van Daniel, ZS4DL
1 - SARL 80 metre QSO Party
2 - Trou herdenking van Erika en Victor,
ZS4VR
2 – All schools close
3 - Hennie, ZS4HG en Frans, ZS4FM
3 – SARL Spring QRP Contest; Club meeting
ZS4BFN
4 – RSGB 21/28 MHz Contest
8 – wedding anniversary of Janet and Mark,
ZS4D; log submission for the SARL 80 m QSO
Party
10 – Amateur Radio in Action, Cape Town; log
submission for the Spring QRP Contest
10 and 11 - AWA Valve QSO Party
12 - Amber Reilly, daughter of Warren, ZS4W,
en Bianca Esterhuizen, dogter van Philip,
ZS4PJ; All schools open
15 – Radio Amateur Examination
16 to 18 – Jamboree-on-the-Air
Page 8
17 – CQ Hou Koers
17 - Harrismith Mountain Race http://
www.amethyst.co.za/Harrismith/
19 - Jianine Jonker, waife of ZS4V
21 - Sarie Greyling, ZS4SG, vrou van Hennie,
ZS4HG en Susan Visagie, vrou van Cgris,
ZS4CV
23 - Stanely Schimper, ZS4TRA
24 – Crafters Market, Bloemfontein
24 and 25 – CQ WW DX Phone Contest
QUA
October 2015 Oktober
A Winning Antenna
A
N.T. “Len” Carlson, K4IWL
few years ago, I rediscovered a facet
of amateur radio that I had long since
forgotten about. I re-discovered QRP!
That brought a renewed excitement to
the hobby as well as a lot of satisfaction at accomplishing what many seem to think is the impossible or at the least improbable but has
many times over shown the true “power” of
QRP, not only as a fun experience, but in its
ability to overcome the seemingly impossible
odds of communicating around the globe consistently.
I had originally tried QRP about 30-some
years ago with a one transistor, crystalcontrolled, transmitter of my own design running about 2 milliwatts and using my Hallicrafters SX-71 on the receive side. It was fun but in
those days, little was available to work with in
building less than 1-watt transmitters.
The “official” definition of QRP is 5-watts or
less output power for CW and 10-watts or less
for SSB. Then there is QRPp, which is generally accepted to be 1-watt or less out for CW.
As with all amateur stations QRO or QRP,
ten percent of a station's success in quality
QSOs is the equipment and the operator. Ninety percent is the antenna. This is especially
true in QRP since with very low power, by comparison to the Power Mongers, we need to get
more ERP per watt out into the ether to be
heard. Therefore, when I got back into QRP a
few years ago I found the fascinating world of
antennas and RF radiators to be an exciting
challenge and a means to find the perfect antenna that I call the New Carolina Windom.
One of my favourite pastimes is taking my
QRP equipment into the woods or other exotic
locations, like an Indian Reservation or a rare
Grid Square and operate my own QRP-
expedition. I have little interest in building or
putting up a beam so I concentrate all of my
antenna research and designs on verticals
(that can be broken down into small packages)
and wire antennas. In the field, I typically use
one of several homebrew verticals since they
are easy to carry and setup. However, in the
last few months as I‘ve become much more active building and using QRPp equipment (like
the RockMite) which I am using at the home
QTH as well as in the field. My goal is to have
a single wire antenna that will fit my yard and
give me the most miles per watt.
I do not have room for an 80-metre dipole
or long wire so I have to restrict the length to
100 feet or less (30 m). Besides my primary interests are working only CW on 40, 30, 20 and
15 metres.
Based upon these parameters, I have found
what I consider the perfect antenna. The antenna I will show you how to build in this article
evolved from a concept that had its beginning
back in 1929. I will briefly discuss the history
before showing you how to build the antenna I
have chosen to be my main antenna for QRP
and QRPp operation.
Let‘s back up 76 years and look at the Windom antenna that came into being when Loren
G. Windom described his invention in the September 1929 issue of QST, pages 19 to 22.
The Original Windom, as I will call it, was
the first known design of an off-centre-fed antenna designed for use by amateurs on the
amateur bands. Its characteristics made it possible to use one antenna to cover all of the harmonically related amateur bands. One of the
drawbacks is that it requires an antenna tuner
and a very good ground system. Although in
those days with vacuum tube transmitters and
receivers, this was not a particular disadvantage.
The original Windom was 130 feet (39,624
m) long with a single-wire feed line connected
approximately at the 600 ohm impedance point
on the radiator. The feed line also acts as a radiator. The original antenna was designed to
be used on 80 metres and all of the harmonically related bands (40, 20, 15 and 10 metres)
using an antenna tuner between the transmitter
(Continued on page 10)
Page 9
QUA
October 2015 Oktober
(National Field Day from page 9)
and the single-wire feed line. The feed point is
37,8% from one end of the radiator. This was
where Loren Windom calculated the 600 ohm
feed point would be located. Figure 1 is a
graphic representation of the original Windom.
Let me briefly mention the G5RV, which has
been relatively popular for the past few years. I
have tried the 102-foot [full size] (31 m) version
of this antenna with moderate success. Two
things you need to know about the G5RV: (1) it
is resonant on no amateur band; and (2) requires a good antenna tuner to make it work.
Both of these factors are not conducive to getting a good signal out when using low power.
For this antenna, I would classify low power as
anything below 100 watts.
A few years ago, three amateurs, Jim
Wilkie, WY4R, Edgar Lambert, WA4LVB, and
Joe Wright, W4UEB, came up with an idea for
an off-centre-fed dipole that carried Windom’s
single feed line antenna to the next level. It has
since become known as the Carolina Windom.
I will call this the Traditional Carolina Windom
since it was the first attempt at creating this
specific type of multi-band antenna based
loosely on Windom’s original concept. The difference between this antenna and Windom’s is
that the Original Windom is not a dipole.
Figure 2 is the electrical equivalent of the
Traditional Carolina Windom.
The Traditional Carolina Windom
Figure 3a is the true representation of the
Traditional Carolina Windom antenna. The
main characteristics are: (1) It is 66 feet
(20,1168 m) in length and designed to cover
the 40, 20, 15 and 10 metre bands without the
need for a tuner; (2) It will also work quite well
on 17 and 30 metres with a tuner; (3) it requires a 4:1 Balun at the transmitter end on allbands except 15 metres and a 1:1 Balun/choke
when working 15 metres. This antenna works
very well and achieves excellent signal reports
Page 10
when up 24 feet (7 m) or higher and when
trimmed and tuned to frequency. You simply
need to cut the antenna (always keeping the
37,8/62,2% ratio to the feed point) to frequency
using the MFJ-259B or similar test equipment.
The feed line from the radiator is 300-ohm
twin lead or 300-ohm ladder-line (which is lighter and can be purchased at many hamfests).
The twin lead must be cut to frequency for 15
metres. Its length must be an odd-multiple of a
¼ wave on 15 metres. To make that simpler, ¼
wave (in feet) at 21,060 MHz is approximately
11 feet (3,35 m) therefore the 3rd multiple is 33
feet (10 m) and the 5th multiple is 55 feet (16,76
m) and so on. I chose 55 feet (16,76 m) since
that was close to reaching my shack from
where the antenna was hanging. Figure 3a
shows a pictorial of the Traditional Carolina
Windom. The 300-ohm twin lead actually is the
primary radiator on 15 metres. As such, a
choke or 1:1 Balun is used between the 300
ohm twin lead and the 50 ohm coax to the
transmitter. A 4:1 Balun is required for the other bands in order to match the higher impedance of the antenna on 40, 20 and 10 metres.
The New Carolina Windom
Figure 3b is a pictorial of the New Carolina
Windom. This more recent version has some
very interesting characteristics. For one, the
(Continued on page 11)
QUA
October 2015 Oktober
removed then you should move the line isolator
to the bottom of the balun.
The following shows the radiation pattern
with no vertical radiator.
The following radiation pattern is with the
vertical radiator in-line.
(National Field Day from page 10)
4:1 Balun has been moved to the antenna radiator and is built into the centre insulator. The
other interesting feature is the 10 feet (3,048
m) of coax from the Balun and terminated in a
choke or line isolator. I have fitted the 10 foot
(3,048 m) stub with PL-259 UHF connectors on
each end. This allows the coax vertical radiator
to be easily removed if desired. It is designed
to hang vertically which is one reason why this
antenna is so effective. Look at the radiation
patterns later in the next column. The radiation
pattern when using the vertical radiator combines both horizontal and vertical radiation
components and lowers the effective angle of
radiation.
This antenna is in use the world over by
DXers and DXpeditions. In one Navassa
DXpedition, of the 33 000 QSOs made, more
than 27 000 were accomplished with this antenna. The DXpedition team also had a beam
and verticals, but the New Carolina Windom
was the antenna they used. Its reputation for
excellent performance is so good that it served
as one of the antennas in setting two 40 metre
“mile-per-watt” world records of nearly 4 000
000 miles-per-watt (6 437 376 km-per-watt).
The antenna can be used without the vertical radiator but the radiation pattern will lose
the low angle component and may make the
antenna less effective. If the vertical radiator is
Page 11
This antenna should not need a tuner on
the 40, 20, 15 and 10 metre bands although
you may use one if you feel the need to. It will
operate on 80, 30 and 17 metres but will require a tuner for these bands.
The following details the making of the Balun and the Line Isolator. The Balun is made
from 1¼ inch (31,75 mm) Schedule 40 PVC
cap and plug plus some additional hardware.
The figures 5a and 5b show the 4:1 Balun
schematic followed by the pictorial. When wind(Continued on page 12)
QUA
(National Field Day from page 11)
ing the balun it is very important to follow the
schematic and pictorial examples so that the
two windings are connected in the correct direction.
Figure 6 shows a correctly wound Balun
and ready to be wired according to Figures 5a
and Sb. For those who have not had a lot of
experience at winding toroids here are a few
tips. To count the number of turns, each time
the wire passes through the centre of the core,
is counted as a turn. For example, if you simply
push the wire through the core it is counted as
1 turn.
To wind this balun you will need one T106-2
toroid core. The wire must be 28 or 30 gauge
enamelled magnet wire. This toroid will be
Page 12
October 2015 Oktober
wound with 21 bifilar turns, which simply
means that it is two coils wound together on
one core. To do that look at Figure 6. Pull 60
inches (152,4 cm) of wire off the spool of
enamelled magnet wire and bend it back on itself at the middle so that you have two 30 inch
(76,2 cm) lengths of wire side-by-side. Do not
cut the two lengths of wire apart until after the
core is wound as in Figure 6. You must wind
the balun by pushing the two parallel wires
through the core for each turn. After each turn
pull the wire tight and space the turns so that
when finished there is about a 30 degree spacing between the ends. Try to keep the two
wires from crossing over each other as you
wind them together. When finished cut the
wires apart where they were folded over. Be
sure to use your ohmmeter to determine which
wires are the A1, A2 and B1, B2 ends as
shown in Figures 5a and 5b. Label these. It is
important that the “sense” of the wires be correct so that all the A and B leads go to the right
places according to Figures 5a and 5b. If you
reverse any of the wires, the balun will not work
properly. The test configuration that you will
setup in Figure 7a will verify if it’s working correctly or not before you install it in the PVC
cap.
In order to test the balun you will need to
wire it as it will be wired in the final balun housing shown in Figure 4. Use a BNC connector
(Continued on page 13)
QUA
(National Field Day from page 12)
and a 200 ohm resistor network (¼ watt resistors are sufficient for the test) and make sure
that they are wired as shown in Figures 5a and
5b. The BNC coax connector will be connected
to the MFJ-259B and the 200 ohm resistance
represents the antenna and are connected
across the balanced leads A1 and B2. Turn the
MFJ on, set the frequency to 3 MHZ and check
the SWR reading. It should read 1,0 SWR.
Then change the frequency to 7 MHZ and so
on moving up the spectrum. The reading
should be flat 1.0 SWR until you get to about
49 MHz. The 200 ohm resistive load across the
core is 4 times the expected 50 ohms at the
BNC connector. Hence, the 4:1 balun is working as it should if you see an SWR of 1.0. If
you add 100 ohms of resistance (300 ohms) to
the load, you will see about 1.2 SWR and at
400 ohms, you will see 1.5 to 1. The 400 ohm
load will translate to 100 ohms at the BNC connector since the MFJ-259 (and your rig) is expecting to see 50 ohms. Figure 7a shows the
balun under test with the MFJ-259B.
October 2015 Oktober
Figure 8 shows the components of the Balun.
See the parts list for more details. Refer back
to Figure 4 for the completed balun.
As shown in Figure 3b, there is a line isolator, which is really a choke to prevent the RF
present on the shield of the vertical radiator
from migrating down the coax, feed line to the
transmitter. The next photo shows the components of the isolator and its enclosure. See the
parts list at the end of this article for the parts
details.
The Line Isolator is nothing more than a 30
inch length of coax folded back on itself with 7
to 10 ferrite tubular cores slipped over the coax. Put an SO-239 (female) UHF connector on
each end of the coaxial choke. I enclosed it in
a CPVC pipe with two end caps and used barrel-type SO-239s. This allows the 10’ vertical
radiator and the feed line from the rig to plug
into the ends. If you remove the vertical radiator and want to plug the Line Isolator directly in
to the balun, use a dual PL-259 adaptor.
We are now ready to make the Isolator or
Choke. The basic components are shown in
the photograph figure 8. I used 1-inch (2,54
cm) CPVC pipe cut to 8 inches (20,32 cm) in
length, two CPVC end-caps, a number of Ferrite tubular cores, two barrel type SO-239 coax
connectors, and a 30 inch (76.2 cm) length of
RG-58 coax.
I chose the CPVC pipe instead of Schedule40 white PVC due to the lighter weight and the
thinner walls which allows a slightly larger area
for sliding in the choke [shown later in this article] and since the barrel type SO-239 connectors are fairly short they mount nicely with
(Continued on page 14)
Page 13
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(National Field Day from page 13)
enough of the connector exposed to screw on
standard PL-259 coax connectors.
To make the choke, cut a 30 inch (76,2 cm)
length of RG-58 and bend it so that it forms
three areas. Two legs and a centre section.
The centre section should be about 6 inch
(15,24 cm) long. If your centre section, due to
different length cores than what I used, is longer than 6-inches make sure that the CPVC pipe
section is 2 inches (5,08 cm) longer than your
choke bundle to allow room for mounting the
coax connectors. Alternately slide 1 inch (2,54
cm) and ⅜ inch (9,525 mm) long tubular ferrite
cores over the coax until they fill the entire middle section. I used a pair of pliers to crimp the
bends in the coax so they fold back tightly over
the cores. This is necessary so that the assembly will slide into the CPVC tube.
When all the cores are in place, fold the
ends back over the cores and use three very
small cable-ties to hold it all together as shown.
Make sure that the coax ends are tightly held
against the cores for a couple of reasons, so
you will be able to slide the bundle into the
tube and to increase the absorption of any radiation by the cores.
See the photo above to see how the filter
will slide into the tube. When completely in the
tube you should only see the ends sticking
Page 14
October 2015 Oktober
out. The next thing you will need to do is to trim
the ends to the best length so that the end
caps will slide onto the tube without bending
the coax ends. Solder the barrel coax connectors on each end as shown below. Then slide
the end caps over them. Before you start soldering, ensure that you have the ground solder
ring slid over the barrel connector. This is what
you will solder the shield to.
Drill the ¾ inch (19 mm) holes in the end
caps for the barrel connectors before assembly. After soldering the coax connectors to the
bundle ends, slide the assembly into the pipe
so that both coax connectors are in place for
the final assembly. Slip the end caps over the
coax connectors and onto the pipe. Allow
enough overlap so that two ¼ inch (6,35 mm)
long sheet metal screws can be used to fasten
the end caps to the pipe. I did not glue mine together since I might need to disassemble it
some time in the future for maintenance.
Parts List
Quantity and Description
66 feet (20,1168 m) Antenna Wire. Radio
Shack #278-1329
2 Antenna Insulators (for the ends)
1 Balun: 1¼ inch (3.175 cm) PVC End Cap
(slip type)
1 Balun: 1¼ inch (3.175 cm) PVC Plug (slip
type)
2 Balun: 5/16 inch (7,9375 mm) x 3 inch (7,62
cm) Eyebolt (Cut-off thread to 1 inch (2,54 cm)
4 Balun: 5/16 inch (7,9375 mm) Nuts
2 Balun: 5/16 inch (7,9375 mm) Split Lock
Washers
2 Balun: 5/16 inch (7,9375 mm) Tubular Lugs
(Outside of PVC Cap)
(Continued on page 15)
QUA
October 2015 Oktober
(20 m Ground Plane from page 14)
2 Balun: 5/16 inches (7,9375 mm) Terminal
Lugs (Inside of PVC Cap)
1 Balun: SO-239 panel mount coax connector
4 Balun: 6-32 screws and nuts for SO-239
1 Balun: T-106-2 (red) powdered iron toroid
core
6 inches (15,24 cm) Balun: 30 gauge enamelled magnet wire
10 Choke: Ferrite Tubes (slide over RG-58U)
30 inches (76,2 cm) Choke: RG-58.
2 Choke: SO-239 barrel type connectors. (Fair
Radio)
8 inches (20,32 cm) to 10 inches (25,4 cm)
Choke: CPVC 1 inch (2,54 cm) pipe. Cut to
length of RG-58 with Ferrite Tubes + 2 inches
(5.08 cm)
2 Choke: CPVC 1 inch (2,54 cm) end caps.
The article is used with acknowledgement to
QRP Expressions.
Issues with ICOM radios that use USB connections
Pieter Jacobs, V51PJ
(I think this might help with other makes too.)
Nowadays we are all starting to upgrade our
radios as all are becoming better and more
tricks are behind the buttons.
When I have upgraded from the IC-706 mk
2G to the IC-7100, I realised with a shock that
the software designed for analogue type of radios do not want to key or control the later designed IC-7100. Looked around on the internet
and finally found it. The program is called
CAT7200 and it is free of charge.
Installation is easy if you read the instructions correctly. Please, read it a few times, otherwise you will get frustrated!
Page 15
Well once installed – remember it is actually
a virtual com port that you are installing – you
are actually, via this software, tricking the older
software to think it is actually talking to a real
RS-232 port. The CAT7200 software converts
this virtual RS-232 port to the virtual RS-232
port that is running on the USB port that is
loaded for the new generation radio.
Hope this will solve some of the frustrations
of upgrading to new radios and still been able
to use your old software.
"Participation is more important than the victory and friendship is worth more than prizes
Bloemfontein Amateur Radio Club
Bloemfontein Amateurradioklub
PO Box / Posbus 33211, Fichardt Park, 9317
e-mail: zs4bfn@gmail.com Web: http://www.zs4bfn.co.za
The Ham Bandstand
Y
Herbert “Mick” Scarpelii, WK9O
ou might check out the Northern California DX Foundation (NCDXF) CW
beacons on 14.100 MHz. They give
an accurate picture of propagation on
that band. Here is what happens; 18 stations
from around the world take ten second turns in
transmitting over a 3-minute cycle. At the beginning of the cycle, you might hear 4U1UN
transmitting its call sign (from the UN HQ in
New York City) followed by four one second
dashes. The beacon call sign and the first dash
is sent at 100 watts, the next three dashes are
at the 10 watt, 1 watt and 100 milliwatt levels.
The next ten-second interval you might hear
VESAT in the Yukon Territories (Canada) doing the same thing. The third 10-second interval is W6WX/B in California, followed by KH6O/
B in Hawaii. Eventually, beacons from New
Zealand, Australia, Japan, Asian Russia, Hong
Kong, Sri Lanka, Kenya, South Africa, Israel,
Finland, Madeira, Argentina, Peru and Vene-
zuela take their tum in the rotation to complete
the sequence before 4U1UN comes on again
to start the next 3 minute cycle.
Equipment used at each site is a Kenwood
TS-50 Transceiver and a Cushcraft R5 vertical
antenna with a controller built by the NCDXF.
The benefits from information gained by copying (and even not copying) certain stations at a
given period should be obvious.
For more information on this and more of
the NCDXF beacon system, check out http://
www.ncdxf.org/beacon.htm. For lists of this and
other beacons check out the massive list of
worldwide beacons compiled by Martin,
G3USF
on
http://www.keele.ac.uk/depts/
por/28.htm
Once you have downloaded the timetable
and if you have a well-calibrated chronometer,
you can tell which beacons you are hearing (or
not hearing) by keeping track of the time.
(Continued from page 2)
people take on positions with volunteer organizations because they fear the organization's
failure.
10. Can you find a way to be a volunteer without killing your time, energy, or finances?
11. What is your level of commitment? Are you
dedicated or are you just mildly interested?
12. Are you risking your safety?
These are but just a few examples of questions you need to ask yourself when thinking of
joining a volunteer organization. Be fair and
honest with your assessment of your priorities.
It's far better not to volunteer, than to say you
will then not live up to your end of the bargain.
Afrika Wysheid
Kindness does not spoil. (Ihsani haiozi)
Swahlli, Oos-Afrika
Die meeste van ons geniet dit wanneer iemand
iets goeds aan ons doen. Ons geniet die bederf
op sigself, maar veral die feit dat iemand aan
ons gedink het. Mense floreer op die ontvang
van liefde van ander mense. Ongelukkig het
ons samelewing baie individualisties en soms
ook asosiaal geword. Daarom betaal eensame
mense baie geld aan terapeute net om iemand
Page 16
te hê om mee te praat. Ander sluit by klubs aan
net ter wille van die sosiale interaksie. Ons
wêreld verlang na mense wat Gal 6:10 uitleef:
Solank ons die geleentheid het, moet ons dus
aan almal goed doen, veral aan ons
medegelowiges.
Aan wie gaan jy goed doen hierdie maand?
© Leon M Foot (ZS4Y)