V

vonjet

Well Known Member
My airplane is newly wired. I plug in my headset (Bose) and there is a humming noise in the background unless I touch the avionics tray or any ground point on the airplane. It goes away. It also goes away if I touch the mic jacks. Is there something wrong? Bad ground somewhere?
 
Are you using the panel power jacks or standard headset jacks? If you're using standard headset jacks, are the mic and earphone jacks isolated from the airframe?

If not, pull the headset jacks away from the panel and let them hang free from touching ground and try it. If it works that way, you just need to get some of these washers.
 
Standard Jacks

The jacks are not mounted to anything yet. They are just hanging in the baggage compartment. I read that the audio wires dont like being next to the coaxial wires for the antenna. Mine all run down the center of the airframe. Maybe they dont like being next to each other.
 
<<there is a humming noise in the background ..>>

Does it sound like "Hi ho, hi ho, off to work we go"? Sometimes I hum that when I'm in the shop and happy <g>
 
Are the wires running to the jacks shielded? If so, are the shields grounded at the intercom? Did you try turning everything else off except for the intercom?

What intercom are you using? What type of plane is this? Many intercoms have a limit for how long of a run you can make to the headset jacks.
 
The antenna coax running along with the audio wires should only be a problem on transmit, and I have seen numerous installations where it was no problem at all.

Mine actually run together for about 6 feet, and are seperated for the next 4 feet, when they were together for the entire run they squeled like a stuck pig... (on transmit).

Sounds more like a ground problem. You didn't say what radio or intercom you have, but most have a wire from the connector directly to ground and don't only rely on the case frame. Also check tht the wires on the jacks themselves are valid. Do you have the same problem with both jacks (pilot and co-pilot) or just one?

Larry
 
I know it's a long shot, but is your power source "clean"? I made the mistake of powering mine up with a battery charger and it hummed like crazy.
 
power is from the A/C battery

the audio panel is garmin 340. I think I found the problem. I need to run a ground wire from my jack mount. I heard the Bose headsets are so sensitive this can be a problem.
Now I just have to figure out my dimmer issue.
 
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