I've got a king 97A comm in my Citabria and it isn't working properly. It started early this summer. It would just be static on and off randomly throughout the flight, but always went away after a bit, however, now it is constant static. Any ideas what it may be? I'm thinking its the radio, but what else could I check out before sending the radio away? And is it worth sending an older radio like that away?

David

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Static could be internally in the squelch circuit or possibly a bad antennae ground. Anybody complaining about your transmitter?

No one has said anything about my transmitting, I think its just me that hears it none stop.

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In that case I would bet on a bad squelch circuit. On the other hand I'm like you, I sit up front and break things that somebody else has to fix.....

we had a simialr issue, different equipment. we had a wire in the back have the cover worn off due to rubbing / vibration, took us a long time to find it, but it is so much better now.

porterjet wrote:In that case I would bet on a bad squelch circuit. On the other hand I'm like you, I sit up front and break things that somebody else has to fix.....

Its the paying to fix it that's hurts me...

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bloomah makes a good point, I'm assuming you have already re-racked the radio and checked for obvious wiring problems.

Have re racked the radio, but haven't gone into the radio at all. Not really in my skill set, and up in Canada we're limited to how much we can take apart...

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I believe they still make the KY97 radio, so it shouldn't be an orphan. My advise is that if you take it to an avionics shop, try to avoid the ones doing the high-dollar avionics suites in turboprops & stuff like that, & look for an old-fashioned repair guy. I've had good luck with a guy who runs an avionics dept in a regular maintenance shop.

So... I still haven't had time to get my plane over to the AMEs place to pull the radio, but I've been flying around and its working great. Just the odd blip of static and other then that its good... any ideas?

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This may sound off the wall but what kind of ELT do you have? I installed a new KY-97A and a new TPX along with rewiring my panel. I then had a similar issue as you describe, our radio tech suggested I disconnect the ELT at the antenna to see if that made a difference. The static went away. I reconnected it and it came back. Did it a couple of times, different conditions, same results. The radio tech said that older ELT installed in my ship can some how generate a signal that will interfere with the comm radio without being activated. I am not an electrical engineer, I don't know the minutiae the details.
I installed a new ELT, I have never had the problem again.
Mike was an old school radio tech, his nickname was Sparks.

A friend had a similar problem in his 182. I asked him about his ELT, it was a older unit, I can't remember which one. He disconnected it and the problem went away, immediately, he reconnected it and it came back. He changed out his ELT with a new one, and had never had the problem again.

This advice is worth what you paid for it.

Cheers,
Dave

Thanks for the advice Dave. I have a brand new as of last November 406 ELT. And its mounted in the tail with no exterior antenna. But the comm antenna is back there also so maybe?? But it is a brand new unit...
The thing that drives me crazy is that its so sporatic. For 10 flights it'll work just fine with maybe an second blip every now and again, and then one or two flights of constant static that makes me just turn the radio off. Super annoying.


David

No problem. I was aggravated beyond belief with my radio issue. I have to say the ELT thing was something I would have never come up with.
Good luck.

Dave

Another item that causes static is a cellphone charger in the cig plug socket.

Electrical and electronic gremlins are wierd. For example, my tv/satellite remote started acting up recently-- when surfing through the satellite station guide, the TV would all of a sudden change from channel 3 causing a screen full of static. Had to click "tv" on the remote, change it back, click "sat" again to get back to surfing. PITA. Thought the remote was going gunnysack. Nah....... put in new batteries, and now it works flawlessly.
I've heard of similar gremlins in car electronics when the battery starting getting old and was producing less than the optimum voltage. Probably not your problem, but something to keep in mind.

Anything that is sporadic like you describe means there's something loose. Most typically it will be a grounding problem, but only an avionics tech can determine for sure--and I'm afraid it could likely be somewhere outside the King box, especially if it is a grounding problem. Good luck.

Cary

Old wires... equals loose wires... and cruddy connections. Save your money on a bench check of the radio for now. Get a flashlight and go under the panel... Check grounds, coax etc.
It might even be cheaper to just run new power and ground and audio wire to the tray.
Any decent engineer (A&P to us) can do that for you.
Something is loose... just hard as heck some times to find out what. Much harder than loose screws in the pilot...
Cheers, Nick