Radio Problem

[Mike Schneider]

The problem is that the tower hears a squeal when I transmit (either radio). So far I've cleaned the battery ground, pulled both radios and cleaned the contacts. I've listened on my hand held while a friend transmitted while switching the alternator on and off, no change in the squeal. Listened while the friend switched between left and right mags, no change. Listened when a load was turned on and off, no change. The only thing (so far) that will change the pitch of the squeal is to change the rpm. I've checked two different head sets, and plugged the headsets in both the left and right sides, no change. I do not hear any squeal in the airplane either when I am receiving, or in the side tone when I transmit. Tomorrow I will clean the contacts to the antennas, the alternator, and the regulator. I am open to ideas to check before taking it to the radio shop. Thanks. - Mike

 

[L10MAN]

Not a radio guy by a long shot. Is this with one headset or have you tried others? Is this just from the LH seat or if you have PTT on both sides have you tried the RH side? Have you tried the hand mike? Well if I'd just read you did say you tried both sides and a different headset. Still the hand mike is worth a shot.
Ron

 

[Tom-D]

If RPM changes the squeal try broadcasting with the engine off. If it doesn't make a noise with the engine off, you have a bad alternator.

 

[Graueradler]

Is it possible that both transmitters are being keyed? That would produce a squeal but shouldn't be affected by engine rpm. You said that you still get it with the alternator off so that should eliminate the alternator. Try transmitting with one of the radios pulled out of the rack.