Comm TX problem
 

I have a intermittent problem with a transmit problem on my comm radio. It is a off and on problem where it will transmit then a little later not transmit. When I can get it to tx I do notice that my panel mounted card compass moves and then when I stop transmitting it goes back to where it was. Any ideas?

Does the "TX" indicator show up when you key the radio?
Is there anything between the mic/PTT and the radio (intercom). If so, what and what model.
What kind of radio?

Bendix/King
 

Yes when it is transmitting yes but then you push again and no transmit and no T showing. Push to talk in the top of the stick and radio mounted on the right side of the fuselage of my RV-3B. Bendix King KX Nav/Com .

Faulty PTT switch or connections?
Make absolutely certain that the radio is pushed fully into the mounting tray.

Yep, sounds like something in the PTT circuit.
My dictum is that 80% of electrical problems are mechanical in nature, i.e. a loose connection, crimp, connector not fully seated, faulty switch, etc. The other 20% are also 80% mechanical!

My transmit problem
 

I recently had a transmit problem, probably not the same as yours, but found to be the headset wires. Fixed by Lightspeed, no charge.

Same for me. Headset on the way to Lightspeed. It was intermittent for one flight and then died. Backup headset worked fine.

-John

Headset
 

Headset was ruled out by trying another one with the same results.
Thanks everyone for their input .