I know that there's been a lot out on the reflector this season regarding
shunt feeding of towers for 160m, and I have been reading along for most
part, but since I've actually tried to do it myself, I've had a few
questions of my own and would appreciated any assistance if possible. Here's
my setup: a 104' grounded Rohn 25G tower with a Mosley Pro-77B 7ele/7 band
yagi on top with a Mosley TA-33 @ the 40' level fixed on Europe. I've got
about 20 on the ground 1/4 wavelength radials for 160m and 3 elevated ones
as well. I've spent some time in the last day or so trying to find the tap
point for the gamma match and haven't really found it yet. I was under the
impression that the top Mosley would provide some "top-loading" and help
extend the tower electrically, but have realized that it, like many Mosley
beams, are isolated electrically from the mast/tower by phenolic blocks in
the boom to mast setup. So, my big question is if I run a strap/braid from
the boom of the Mosley to the tower, what detrimental effects on part of the
yagi can I expect?? I don't
believe at this point that it'll affect the SWR much if any, but the pattern
could be another thing entirely. Any ideas? I should have mentioned earlier
that all my guy wires are broken up with insulators starting approx. 3' from
the tower itself. I'm going to try to call Mosley after the holidays to run
this by them, but am unsure what help that they can provide and would like
to know if anyone else out there has tried this. The highest tap I've done
so far is at the 72' level, and it wasn't enough, at least w/o the yagi top
loading. Please direct any/all replies to me directly and if there's
sufficient interest, I can summerize the results for the reflector. Thanks
& 73,
Daniel Baker/K4DB
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