re Using a boom for 40mx
I would like to confirm Tom N4KG's remarks about feeding the boom of a TH6
or similar sized antenna for 40mx.
I use the same set-up here on a 204BA with two gamma rods along the boom.
(1) rod about 2 mx long towards the director end and omega matched for 30mx and
(2) rod about 4 mx long towards the reflector end and omega matched for 40mx
The hardest part is adjusting the omega match in-situ, as adjustments near
the ground are useless.
Nevertheless, the system works well, high powered, relatively lossless, some
directionality off the ends (more so on 30mx than 40mx) and cost about $20
for the rod and capacitors.
In Tom's case, he measured the required capacitors and replaced with coaxial
cable, I use fixed high voltage ceramic (transmitting) and mica capacitors.
The voltages are quite low at the feed point as both gammas are
significantly long at the frequencies involved.
Bandwidth is more than adequate, and can be compensated for by an external
tuner if required.
Heartily recommended
Cheers
Peter VK3QI
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