|In the summer of
2005 a ham buddy, Eric Handly KA1NZA, and I decided to put up a couple of G5RV
antennas to play with over the long Vermont winter. We bought the
Buxcom versions of the G5RV. Both (Rutland and Wells, VT) were
mounted about 40 feet up. Both worked great, until that is, mine
I was running 700 watts working
some DX on 40 in the evening when Vermont decided to deliver rain and a
1/4 inch ice storm. In the morning, the driveway was unusable and
so was the G5RV which went dead. The balun was shorted on the
input side. Whether it was high power, water and ice, both, or the
RF devil, who knows? That said, here is what the inventor of the
G5RV, Louis Varney, had to say about using a balun with the G5RV antenna:
It is now
known that if a balun is connected to a reactive load presenting a SWR
of more than about 2:1, its internal losses increase, resulting in
heating of the windings and saturation of its core (if used). In
extreme cases, with relatively high power operation, the heat
generated due to the power dissipated in the device can cause it to
burn out as well as the PL jacks. However, the main reason for not
employing a balun in the case of the G5RV antenna is that, unlike an
antenna tuner which employs a tuned circuit, the balun cannot
compensate for the reactive load condition presented to it by the
antenna on most of the HF bands, whereas a suitable type of antenna
tuner can do this most effectively and efficiently.
(Construction guide of the G5RV (II).
reading what Varney has to say about baluns and what other hams on 40 cw
had to say about them, off came the balun and on went a 9-1/2 turn home
made RF choke made out of coax cable (to keep the shield from radiating)
and a Folger's coffee can. The G5RV is back in business and better
than ever. The images below can be clicked for larger versions.
||Lesson learned. Do the
research. Do the reading. Then, do more research, and
more reading. Then, build the antenna yourself!
Typically, home brewing an antenna like the G5RV can be done
better and cheaper then buying it commercially. So then, come
the summer, there should be a 160 meter full-wave horizontal loop
going up. Vermonters really do put up antennas in the
summer. The other homebrew antenna is an inverted-L that
is a full wave on 40 meters with a 33-foot vertical leg.
Works great on all bands and the Palstar AT1500CV transmatch does a wonderful
job of matching it, as it does with the G5RV and anything else
that I throw it's way.
73, Jozef WB2MIC