Last night, when there were signals to be heard on 160 m, I began
some listening tests. I have a set of K9Ay loops for low band rx.
Even with a mismatch, the shunt fed vertical should hear well, but I
found that it was at least 10 dB down (by ear) from the loops,
*without* the loop's preamp.
This morning, I've substituted a known good transmission line for the
one in use but that changed nothing. So, I looked carefully at the
the connector I used for feeding the shunt: a PL-259, the center
feeding the shunt and the shell grounded. The part I could see looked
fine, but when I fed about 20 w to it, it got warm. Not right.
So, I removed it and looked in the other end. It's filled with
carbon. That is the problem. I'll replace it with a real feedthrough
and use a separate ground lug. Someone asked if I were using
feedthroughs and I said no, But, I should have been! I had forgotten
that I had a couple of old ones and, instead of using the proper
components, I used what I had on hand. I should know better.
Now, If I can just figure out how moisture is getting into that box,
I'll be set. Actually, I think what I'll do is drill some 1/4" to
1/2" screened holes in the bottom, so any moisture that gets in has a
way out, but with screen small enough to keep insects out.
My thanks to all who responded.
Happy New Year,
Kim Elmore, N5OP
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