moto657
Filing Flight Plan
- Joined
- Dec 5, 2019
- Messages
- 9
- Display Name
Display name:
moto657
I am getting really bad high pitched feedback in the headset. It’s always been there, but I’ve been flying a bunch lately. It’s really annoying and has my tinnitus ringing really bad now.
My Equipment:
- TKM MX 11 Com
- Softcomm panel mount 4 place stereo intercom.
Last night I did some testing to understand interference sources.
1. Turning the intercom off or on made no difference.
2. Radio on with engine off and all loads off is quiet.
3. Alt field switch on with engine running. RPM tracking high pitched whine. Biggest contributor.
4. Strobes on. Pulsing high pitched. Second biggest contributor.
5. MX11 display when on bright causes high pitched whine. Really weird. It has a photocell to auto dim. When it’s dimmed no noise. Lucky I was testing in the dark and noticed this when the headlamp hit the photocell.
6. Nav lights and Skybeacon on. Very quiet high pitched.
7. Map/interior lights, no effect.
8. Taxi/ Landing lights. They are blown out now, or not working. Add that to the list!
Ground loop issues, right?
Based on some research I started troubleshooting by checking all of the jacks for headsets to be sure they are isolated from the panel/airframe.
1. None of the jacks have fiber insulation washers.
2. To remove the jack to panel ground loop I pulled the retaining nuts off all 8 jacks and moved them away from the panel.
3. Plugged in headset and turned radio on to test. Radio out put was minimal. At full volume sound is very faint.
4. Headset speaker jack body needs to be touching panel (grounded) to hear normal radio volume output. Same result at all 4 headset positions.
So now I am thinking that the jacks are not wired properly. Seems they need to have a ground lead ran back to the common radio ground. Then isolate the jack bodies with fiber washers.
I am not great with electrical, and no audio experience, so please let me know what you guys think.
My Equipment:
- TKM MX 11 Com
- Softcomm panel mount 4 place stereo intercom.
Last night I did some testing to understand interference sources.
1. Turning the intercom off or on made no difference.
2. Radio on with engine off and all loads off is quiet.
3. Alt field switch on with engine running. RPM tracking high pitched whine. Biggest contributor.
4. Strobes on. Pulsing high pitched. Second biggest contributor.
5. MX11 display when on bright causes high pitched whine. Really weird. It has a photocell to auto dim. When it’s dimmed no noise. Lucky I was testing in the dark and noticed this when the headlamp hit the photocell.
6. Nav lights and Skybeacon on. Very quiet high pitched.
7. Map/interior lights, no effect.
8. Taxi/ Landing lights. They are blown out now, or not working. Add that to the list!
Ground loop issues, right?
Based on some research I started troubleshooting by checking all of the jacks for headsets to be sure they are isolated from the panel/airframe.
1. None of the jacks have fiber insulation washers.
2. To remove the jack to panel ground loop I pulled the retaining nuts off all 8 jacks and moved them away from the panel.
3. Plugged in headset and turned radio on to test. Radio out put was minimal. At full volume sound is very faint.
4. Headset speaker jack body needs to be touching panel (grounded) to hear normal radio volume output. Same result at all 4 headset positions.
So now I am thinking that the jacks are not wired properly. Seems they need to have a ground lead ran back to the common radio ground. Then isolate the jack bodies with fiber washers.
I am not great with electrical, and no audio experience, so please let me know what you guys think.