RCI 2970 (old style, not DX)

[Steve B]

Trying to troubleshoot problem. No AM audio. Good carrier signal. SSB starts to modulate then pegs meter? Microphone checked as OK.

Any help appreciated! Steve B

 

[Robb]

See if it works in PA mode.
Try another mic.

 

[ExitThirteen]

Check the 2SB754 regulator transistor that's mounted behind the audio chip. It'll be labelled B754. If you have no AM audio, but have a deadkey, it's possible this regulator transistor has gone fault. If memory serves me right, I think it does also affect SSB too. Let us know how you get on.

Oh, if the radio has a "swing" or "NPC" mod done to it, have it removed. These mods can potentially damage this transistor.

Good luck!