Comm Problem

Hi all,

I’m experiencing some problems with my aircraft comm installation for a couple of months. My aircraft is equipped with the AVCOMM DX-AC6PA intercom and a Microair M760 radio. Everything was working perfectly for a year and a half and then the problem appeared slowly.

It started with bad transmissions. Each time I pressed the PTT the sound was weird in my Zulu headset ant other reported that the transmissions were noisy with crackling. Then, I started to have bad reception. And now, it’s like if I hear all the cabin noise in my headset. Even if I adjust the intercom and radio squelsh it’s very noisy.

I checked all the connectors to ensure everything was properly plugged. I tested it with the engine stopped and the comm seems to be perfect. It’s only in flight. During my last flight I unplugged the micro line of my headset and everything turned quiet. I also tried another headset model to make sure and the problem was still there. So this is not a headset problem.

I searched on the web for similar problem and some have experienced almost the same. It appears by adjusting the mic gain and sidetone on the radio would help but I thought the mic gain would help only when I press the PTT, not during all the flight. Also, is the sidetone and mic gain can disadjust by themselves?

I need your help!!!

Best regards,

Patrick Caron

Looks to me like an aerial of feeder issue?

Hi Patrick,

I have the same radio and had some of the same issues. If you can, keep the mic gain low. I know it's not a good idea, but I ended up grounding the radio case. I also made sure the mic jacks were grounded properly. I ran all of my grounds back to the same point.

This is not the greatest radio, but I've been able to make it work in most ATC environments. Hope this helps...

Russ

Russell, you're the man!!!!

First of all, I want to thanks everybody for your help and advices. The Kitfox community is so great. We have to keep going on and continue to support each other.

Good news!!! Problem solved last night. I went to the airport and started by rechecking all the connections and tapping every screws. Didn't help as everthings were already all right. Then, I realized with somes tests that the problem was from the radio. When I turned the radio off and was using the intercom only, the problem disappeared. As soon as I turned the radio on it was like if my micro was permanently activated. At the begining I had doubt that it could be the micro gain because people who experienced mic gain problem reported it was only when they activated the PTT.

Finally, I removed the radio completly from the dash because Microair doesn't have any mic gain adjustment in the menu. You have to adjust it by a screw on the side of the radio. I lowered down the mic gain and tested it and what a surprise. My comm has never been so clear. I just wondered why the mic gain disadjusted by itself after a year and a half of good work??? Anyways, I wanted to share my experience to all of you. If it can help only one pilot who experiment same problems, the mission is accomplished. :D

(sorry for my limited english!!!)

Pat