Since this issue involves coaxial cable and antenna wiring, I hope it's
close enough to on-topic to belong on Towertalk.
I'm setting up a classic Top Ten SO2R configuration, with two 6-way Top Ten
relay boxes driven by band decoders, followed by 6 A/B relays. Going step
by step, I have connected a transmitter (actually a transceiver) through
one 6-way to a dummy load. I have a receiver (actually another
transceiver, on receive) connected through the other 6-way to a dummy load.
Checking for isolation, in what should be a very well isolated system
(since there are no cross-coupling possibilities yet), I was getting much
too much transmitter signal in the receiver (on 160 M). Going back a step,
I found that if I connected the dummy load to the receiver antenna
terminals or to the jumper from the receiver to the Top Ten relay box, the
transmitter signal level on the receiver was very low (no S-meter
movement). But as soon as I connected the jumper to the relay box and put
the dummy load on its output, the signal jumped up close to S9. the same
was true if I left the receiver going through the Top Ten box, but
connected the transmit dummy load directly to the transmitter (through the
jumper that would otherwise go to the Top Ten box). The received signal
dropped to S0, but went back up to S9 when I fed the transmitted signal
through its 6-way box to the dummy load.
I can't for the life of me figure out how the signal is getting from the
transmitter to the receiver. The relay boxes themselves are well shielded,
and I *think* my tests tend to rule out defective jumper cables. The
control lines for the two boxes are well by-passed.
Any ideas?
73, Pete N4ZR
The World HF Contest Station Database
was updated on 21 June 2005
2965 contest stations at
www.pvrc.org/WCSD/WCSDsearch.htm
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