Welcome! Becoming a registered user of ShortWingPipers.Org is free and easy! Click the "Register" link found in the upper right hand corner of this screen. It's easy and you can then join the fun posting and learning about Short Wing Pipers!

Thanks Thanks:  0
Likes Likes:  0
Page 1 of 2 12 LastLast
Results 1 to 10 of 13

Thread: Radio Whine Troubleshooting

  1. #1
    moto657's Avatar
    Join Date
    Aug 2018
    Location
    Canyon Lake, CA
    Posts
    122
    Post Thanks / Like

    Default Radio Whine Troubleshooting

    I am getting really bad high pitched feedback in the headset. Itís always been there, but Iíve been flying a bunch lately. Itís 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 itís 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.




  2. #2
    Brian's Avatar
    Join Date
    Jan 2008
    Location
    Monrovia, CA
    Posts
    818
    Post Thanks / Like

    Default Re: Radio Whine Troubleshooting

    Some good troubleshooting info on AvWeb:

    https://www.avweb.com/ownership/lick...ernator-whine/
    Brian
    Monrovia, CA

  3. #3
    moto657's Avatar
    Join Date
    Aug 2018
    Location
    Canyon Lake, CA
    Posts
    122
    Post Thanks / Like

    Default Re: Radio Whine Troubleshooting

    Quote Originally Posted by Brian View Post
    Some good troubleshooting info on AvWeb:

    https://www.avweb.com/ownership/lick...ernator-whine/
    Thanks for the link. Read through it. Hope I don’t have to get that deep to solve it.

  4. #4
    Glen Geller's Avatar
    Join Date
    Dec 2007
    Location
    Beaverton, Oregon, United States
    Posts
    1,340
    Post Thanks / Like

    Default Re: Radio Whine Troubleshooting

    I ran across this and thought of your thread
    I've linked to "the money shot" but the whole article is somewhat informative and could be useful:
    https://mooneyspace.com/topic/27296-...comment=461601

    GG
    Glen Geller
    1955 PA22-150 "One For Papa!"

  5. #5

    Join Date
    Sep 2019
    Location
    Marana, AZ
    Posts
    41
    Post Thanks / Like

    Default Re: Radio Whine Troubleshooting

    I have found that if you run the ground from the jacks back to the radio you can fix 75% of your noise problems. Same with the power supply to the strobes. I have the pwr supply mounted in back but grounded at the instrument panel, I have no strobe noise. I put fender washers on the jacks so that they don't ground out on the airframe, and run the ground to the radio or the audio panel. Seems to work great for the Tri-pacer and any other aircraft that I have installed the equipment.

  6. #6
    moto657's Avatar
    Join Date
    Aug 2018
    Location
    Canyon Lake, CA
    Posts
    122
    Post Thanks / Like

    Default Re: Radio Whine Troubleshooting

    Quote Originally Posted by Glen Geller View Post
    I ran across this and thought of your thread
    I've linked to "the money shot" but the whole article is somewhat informative and could be useful:
    https://mooneyspace.com/topic/27296-...comment=461601

    GG
    Thanks for the link Glen.

    Quote Originally Posted by EdH View Post
    I have found that if you run the ground from the jacks back to the radio you can fix 75% of your noise problems. Same with the power supply to the strobes. I have the pwr supply mounted in back but grounded at the instrument panel, I have no strobe noise. I put fender washers on the jacks so that they don't ground out on the airframe, and run the ground to the radio or the audio panel. Seems to work great for the Tri-pacer and any other aircraft that I have installed the equipment.
    Thanks for the info Ed! Really appreciated. Do you use special shielded wire or just regular insulated wire for the ground runs?

    I’m out at the airport now. The head phone and mic jacks are both just grounded through the jack body to the panel. No other ground wires run. Hoping proper grounding will help. Do you use the insulating fiber washers and run a central ground for the headset jack as well as the mic jack? I looked at the instructions for a Sigtronics intercom and they only show insulating the mic jack and running it back to the central radio ground. Nothing specific for the headset jack ground.

  7. #7
    moto657's Avatar
    Join Date
    Aug 2018
    Location
    Canyon Lake, CA
    Posts
    122
    Post Thanks / Like

    Default Re: Radio Whine Troubleshooting

    Just did a quick test to see if the grounding on the jacks is the issue.
    1. Located the central ground for the radio, intercom, transponder.
    2. Pulled all of the mic and headphone jacks out of the panel.
    3. Ran a jumper from the pilot headphone jack ground lug to the central ground.
    4. Plugged in headset. No improvement to feedback when electrical loads are turned on!

    Now I am out of ideas.

  8. #8

    Join Date
    Sep 2019
    Location
    Marana, AZ
    Posts
    41
    Post Thanks / Like

    Default Re: Radio Whine Troubleshooting

    Yes I did use a fiber fender washer and Shielded 22 wire. I also used a fiber washer. Fender washer from the back, fiber washer on the front. I also use them on the headphone jacks. I am also running the Sigtronics system, mine is crystal clear. I have had problems with the headphones themselves at times. and the jack itself. Also running stereo and mono headphones at the same time can cause problems unless you have a newer setup with a failsafe. I have had other people fly with me and when they plugged in nothing would work right. Are you running a audio panel or just straight to the radio? I have also had to replace the units themselves. Had really bad communications couldn't find a problem, pulled the audio panel slid in another one, same tray, was a tad worse, tried another one and worked perfect. Sometimes having a bunch of old radios and audio panels helps. Don't know if this might help but I ground the jacks to a ground from the radio, not the tray or grounding block, and then ground the shield wire to the grounding block on the radio.
    Last edited by EdH; 11-09-2021 at 07:51 AM.

  9. #9
    moto657's Avatar
    Join Date
    Aug 2018
    Location
    Canyon Lake, CA
    Posts
    122
    Post Thanks / Like

    Default Re: Radio Whine Troubleshooting

    Quote Originally Posted by EdH View Post
    Yes I did use a fiber fender washer and Shielded 22 wire. I also used a fiber washer. Fender washer from the back, fiber washer on the front. I also use them on the headphone jacks. I am also running the Sigtronics system, mine is crystal clear. I have had problems with the headphones themselves at times. and the jack itself. Also running stereo and mono headphones at the same time can cause problems unless you have a newer setup with a failsafe. I have had other people fly with me and when they plugged in nothing would work right. Are you running a audio panel or just straight to the radio? I have also had to replace the units themselves. Had really bad communications couldn't find a problem, pulled the audio panel slid in another one, same tray, was a tad worse, tried another one and worked perfect. Sometimes having a bunch of old radios and audio panels helps. Don't know if this might help but I ground the jacks to a ground from the radio, not the tray or grounding block, and then ground the shield wire to the grounding block on the radio.
    I have:

    - TKM MX 11 Com
    - Softcomm ATC-4PS, panel mount 4 place stereo intercom.

    Iíll try grounding the jack to a couple other spots.

    Interesting that you have had radios that have feedback issues that had to be changed. The fact that I am getting feedback from the radio display when itís on high brightness makes me question the radio.

    Thanks again for all the help. I need to figure this out, the high pitched whine in the headset is wrecking my ears.

  10. #10
    tnowak's Avatar
    Join Date
    Dec 2007
    Location
    Hampshire, England
    Posts
    788
    Post Thanks / Like

    Default Re: Radio Whine Troubleshooting

    Do you get interference under this scenario?:
    1. Intercom off.
    2. Only one headset plugged in.
    3. All electrics off, except for radio on.
    4. Engine off
    Any interference?

    Then try this scenario?:
    1. Intercom off.
    2. Only one headset plugged in.
    3. All electrics off, except for radio on.
    4. Engine running but alternator off.
    Any interference?

    Then try this scenario?:
    1. Intercom off.
    2. Only one headset plugged in.
    3. All electrics off, except for radio on.
    4. Engine running and alternator on.
    Any interference?

    TonyN

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •