Radio Issue

Hi all,

Having a bit of a radio issue in my '71 Beech that I'm hoping someone may have had before. Since we bought it, the radios have been a little bit scratchy but recently have taken a turn for the worst. It slowly became harder and harder to hear incoming transmissions through the headset, which eventually led to only being able to hear through the speaker and now not being able to hear any transmission at all. The radio transmits loud and clear (we checked with a handheld) and the intercom works just fine, it's just incoming transmissions that we are having the problem with. It's probably important to note that the airplane doesn't have a true audio panel and the two radios are a Bendix King KX-125 and a Genave. Has anyone ever had this problem before and if so how expensive was the fix? Thanks

 

Both radios doing it?

Are both radios “always live” in the headset or is there a switch between them and the headset jack, since there’s no audio panel?

 

Start by tracing the headset wiring back to switch system used for radio selection and the radio’s connector for dirty contacts. If both radios, likely culprit noise physical connector. Also could be a failing electrolytic capacitors that act as DC signal blockers or filters.

You can’t imagine how nice it is to have a stereo audio panel like a PS 450B.

 

You can choose to transmit on one or the other but both are always active for receiving

 

Thanks! An audio panel is definitely on the wish list but unfortunately that’s a rather long list right now... gonna have to make do with the handheld for now

 

And are both experiencing the receive noise?

If you turn one all the way off does it go away?

How about all other electrical devices on board?

Any logical troubleshooting whatsoever?

 

Please answer this question before we go any further. If the two radio headset/speaker wires are tied together with a redneck adder (i.e. just spliced together) you will get just exactly what you you are describing.

Jim

 

Was thinking the same thing, Jim.

I ask, and no answer. Sigh.

 

Asked this question on beechaeroclub.org yet?

 

Probably a dumb comment, but hey, why should I stop now, right? Are you using a portable intercom....and, if so, have you tried a fresh set of batteries? That wouldn't explain the speaker part of the original post, but all of the other symptoms are similar to what happens when my intercom batteries get weak.