Not and expert in the TKMs but it sounds like the radio doesn't get audio input from your mike on the "mike audio" pin. This input(wire) may either come from the intercom or directly from your mike jack. Your plane will probably have been fitted with some kind of ARC radio before the TKM. On the ARCs "mike audio" is pin "M". Your plane could also have been fitted with one of the old King KX 170/175 types. In that case you're looking for pin "39". Try and backtrack this wire to determine if its properly connected at both the radiotray and either the mike jack or the intercom output.

Just a thought.


Sincerely

J

Since I don't have a copy of the 1967 Cessna radio wiring diagram, can anyone tell me if the microphone jack has one or two wires running to it? My jack is located on the right side of the trim wheel cover and I am fairly certain there is a loose wire in it. I plan on pulling the cover Saturday and inspecting the wiring but it would sure help to know what I am looking for.

I have every book available for the 1967G model 150 except the radio wiring manual. I would appreciate any help anyone can provide.

Thanks!
Reece

I always try to post the solution when I ask a question here. Yesterday I pulled the trim cover and looked at the back of the mic jack. Sure enough, it had a wire that had pulled loose. This was probably done by me when I was reinstalling the intercom after putting the trim cover back on. There were two wires leading to the jack and it does ground through the frame as Jay said.

Thanks to everyone for their input.I'll solder the wire back on Saturday.
Reece

I have a 172m with a TKM MX300 and Flightcom 430mc intercom.  The problem is, no sidetone.  The aircraft had a RT308 from the factory, and I'm guessing that I'm missing some wiring.  Any suggestions would be appreciated.

Thanks!