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mag static in headsets

CuBob

FRIEND
I am getting static in my headset that I believe is coming through the Mag's. As RPM increases the static frequency increases as well. My Mag switch is located within 4 inches for the headset jacks could this be causing the problem? Any suggestions would help. Before anyone asks, no I did not shut the mag switch off in flight to see if it made it stop (then I would have to change the seat cover)
 
Sometimes it can be mag but try this. Clean your battery ground first, both ends. Then try turning off your alternator in flight to see if it might be a bad diode.
 
No need for plastic seat covers!

Do you get the noise on the ground and in the air, both? Does it change when you do a mag drop test? Have you turned off the alternator/regulator when you hear the noise? Does that change it? Has it always done this or did it just start?

Web
 
Does it come in through both headset jacks? Does it happen with two different headsets through the same jack?
 
Noise occurs in all situations with engine running, no alternator on aircraft ( using small rechargeable battery). Noise reduces small amount on single mag, as always done it, noise comes through both headsets, have tried alternate headsets.
 
Make sure no wires are bundled with your p-leads. Also, use shielded wire for the p-leads. Tie one end of the shield to the mag body and the other end of the shield to the ground tab on your switch. This will keep the electrical noise out of the airframe. Then make sure that you have isolation washers on your mic/phone jacks.

Web
 
I like wirewienie's idea that you may not have isolation washers on your mic and phone jacks.

If your frame has ever been sand blasted and epoxy coated, make sure that the ground lead going straight from the battery is attached to a point on the frame where the epoxy has been sanded or wire-brushed off.

Do you have ANR headsets? If so do you get the static with the ANR off?

Does the static happen with the intercom off?
 
I had intermittent static problems with my KX155 and after exhaustive trouble shooting/trial and error turned out to be caused by the USB cigarette lighter charger when charging either my I-phone or I-pad. Not all frequencies were effected consistently and the radio seemed to transmit clearly all the time.

I even took the radio to an avionics shop in Kenai (but I will not mention their name) and they luckily didn't have time to work on it as their estimate for fixing was cheaper to replace it than fix it.
 
I isolated jacks and cked p-leads. No change in the mag noise. I did a continuity ck on the jacks and every part of the jack is grounded to the airframe. Unplugged radio harness (flight line 760) tall post on the jack is isolated. Cked pin on the radio #14 headphone output and that is grounded to the radio case, thus grounding the jacks. This doesn’t seem correct. Calling flightline this week. Decided to go fishing and think. Thanks CuBob for connecting me up with SC.org.
 
Unplug all headphones/mics/music. The ONLY part of ANY jack that should read directly to ground is the threaded part with the nut on it.

Is this an ongoing problem or has it just started?

Web
 
I isolated jacks and cked p-leads. No change in the mag noise. I did a continuity ck on the jacks and every part of the jack is grounded to the airframe. Unplugged radio harness (flight line 760) tall post on the jack is isolated. Cked pin on the radio #14 headphone output and that is grounded to the radio case, thus grounding the jacks. This doesn’t seem correct. Calling flightline this week. Decided to go fishing and think. Thanks CuBob for connecting me up with SC.org.

No, ISOLATE FROM AIRFAME. ONLY GROUND AT RADIO


Sent from my iPhone using SuperCub.Org mobile app
 
New radio, purchased 2 Year’s ago. Flew cub first time last fall. Experimental. On going problem from the start. Airframe is grounded to the battery. Radio grounded to the battery neg. buss.
 
Shielded wire on leads, routed with no other wires. Connected shield to mag grd screw and to grd terminal on mag switch. No other grds connected. Slick mags are new. 32 hrs on exp. cub
 
Yea, I did use shield wires for phone and mic jacks, open on one end.. What baffles me is why the headphone pin on the radio is grounded internal in the radio. The harness cked out good one wire at a time. I do transmit and receive well, except for the noise.
 
Yeah, if the p leads are making good connections....wouldn't take a minute with a wire and alligator clips to check?? plug wires? the little spring thingy in the spark plug wire end.?
 
I chased radio noise that only occurred on 122.8 for several years. It finally went away when i replaced 3 spark plugs. Stranger than fiction but it was true.
 
One last idea - can you hear the noise on a handheld when the engine is started? If so, that would help isolate the problem to the ignition wiring itself.
 
I did the hand held thing. Still had mag noise. One last try. When I built the airplane, I acquired some really cool wire loom. It looked like a rattle snake skin, nice shiny aluminum with fire resistant glass on the inside. I put my p- leads thur that on the firewall. A big giant antenna. It’s gone now and so is most the noise. Thanks for all the help. I know my electrical system better than ever. Keep the wheels pointed down.
 
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