"three-eight-hotel" wrote:
I've decided that I'm going to pull the radio and the connector
tray and run new coax from the radio to the antenna,

I've read your symptoms per your orig post, and you have one odd
collection of seemingly mutually-exclusive symptoms. If you can
xmit, but not receive, it's not the coax. Scratchiness, followed
by silence, isn't likely the connector, nor coax. Is that what it
still does? It sounds like a thermal fault in the squelch
circuitry. Narco uses a large fancy squelch circuit, squelching in
2 different ways and works on a hair trigger. Bad thermal behavior
of a component could cause grief. My Narco comm 120 does similar
and obviously a thermal, w/o the annunciating scratchiness.
Similar circuit; no time to pull and fix in such nice weather yet.

You can't pull the tray without dealing with the wires at the
connector. If you can do that, you can just visually inspect the
stuff for integrity. May take just an inspection mirror. I'd use
my $400 flexible, illuminated, magnifying boroscope. Next colon
cancer check, I'm using that to then check that doctor!

An avionics tech can visually check your connector from the front,
knowing what looks normal. He can maybe feel for integrity of the
wire connections from the back, having fondled hundreds. That's
why it's easy for him; hard for us.

For thermal, did you try flying w/o any box above and below the bad
one? That's how I know my 120's a thermal glitch.

Per other post, RG-400 will cure anything, nor do much
performance-wise at VHF.

Good luck!

Fred F.