I'm guessing that the transmitting antenna is going to need some real work
to get it appropriately detuned. Remember, the K9AY is lots of dB down in
absolute signal level, meaning its rear null is very sensitive to coupling
of anything else to the antenna.
This includes the feedline shield, but I think you can still get some pretty
serious coupling between a full wave loop 90 feet away and a K9AY. I tried
it quickly in EZNEC (not knowing all the details, of course) and with the
loop feedpoint shorted the pattern is totally destroyed and becomes just
that of the loop.
If you do open the loop feedpoint, and it's a vertically fed loop, that
should largely eliminate the problem... I would probably try to resonate the
feedline to put very high impedance at the feed.
You can get a K9AY model from K7TJR's site:
http://www.k7tjr.com/rx1comparison.htm
And then you can "install" your loop and play a bit.
73
Dan
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