Dave,
While I have not had the problem you have on an Omni VII, I have had it
with another Ten Tec rig. Only it was not the fault of the rig. It was
a bad coax jumper cable to an antenna switch. The shield was making a
bad connection, and was affected by movement or thermal warm up.
Other causes could be a loose ground lug, loose connector internal to
the rig, or anything inside that is acting as a RF ground, but is loose
and affected by rig operating temperature cycles. I don't think it is a
"component nearing a failure". It is something that is thermally
affected, and those are usually loose connections of some type. It could
even be a solder joint that was missed, or did not wet completely and
provide a low impedance ground. Check in the circuits of the ATU, after
trying new or known good coax jumpers. Do you have a grounding lead
connected to the back of the radio, and is it tight, at both ends? The
only components in the ATU are fixed inductors and capacitors, switches
or relays, things that don't typically gradually fail. (With the
exception of relays that in some types acquire permanent magnetism after
many, many uses.) Look for things that could move with thermal cycling,
loose connections, and then look a the solder joints. A strong light
and a magnifier can help with those.
Let us know, what you find. I don't expect a reset to help, so would
leave that to last after all other options. As simple a cause as a PL
259 not completly tight can cause such an RF connection problem as to
cause feedback.
-Stuart Rohre
K5KVH
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