radio noise

On Nov 26, 9:18*am, Orval Fairbairn
wrote:
In article
,

*et wrote:
I have a radio question. * Glasair 1TD with Icom radio, older headset..
When the engine is running and charging 14.5 volts the radio howls
when I transmit. * Engine off, battery voltage, no noise. * *If I put
a small screwdriver in the small hole in the headset and turn it down
1/2 turn, no noise. * If I then take the headset and plug it in my old
Cherokee, it won't transmit until I turn it back up.

Are all headsets this voltage sensetive? * Or just older ones? *Is
there a fix?

thanks

Ed

You need a capacitor between the alternator o/p and ground, to suppress
noise. All the aviation supply houses sell noise suppressors.

It's not that kind of noise, it's a loud howl when I try to transmit,
receives great. It will also howl after I shut down the engine,
until the battery voltage drops a little, then it transmits great.
Never does it when receiving.

Ed