Garmin 396 audio noise

[DanB]

Well, after 20 hours of engine time and dealing with what I thought was a ground loop, I have isolated the problem area. I found it to be entering the intercom via the audio out on the 396. I was hearing a high pitched whine that followed the RPM of the engine. I went around the block on this one trying to eliminate the "ground loop" through what I thought was due to a double-grounding in either the 396 and or the PS 1000 intercom. Moved all ground wires several times trying to find the little gremlin. As it turned out, it was entering through the hot wire feeding the Garmin. I determined this after talking to a factory Tech. for about 15 minutes. He finally admitted that the 396 lacked in the arena of internal filtering. He said he rarely has a customer call with this problem when it is a 496 or newer. So, the fix was an in-line audio filter and now all is quiet as it should be. Just thought I'd share this one if it can help someone at a later date.

[bdemunck]

Dan,

We have the same problem with our 496 with XM. When not listening to music, we're listening to a high pitch whine in our headsets. This plug-in sits between the co-pilot's mic and headset plugs. Our solution has been to disconnect the XM plug-in for some peace and quiet.

What inline audio filter did you use and how did you set it up or connect it? We may need to do this to!

[DanB]

Bdemunck,
What worked for me was this filter www.amazon.com/gp/product/B001EAQTRI/ref=oh_details_o00_s00_i00
I plugged it into the 396 audio out and sent it along to the intercom.
It sure is worth the low cost if it works out your whine.
Dan

[bdemunck]

Thanks Dan for the help!
Bob

[N276KM]

I'm glad that this was posted. I have a garmin 396 that I plug directly into my Bose A20 headsets for music. When the 396 is hard wired into the plane's electrical system I get the same high pitched noise unless I have the music on to mask it. I also "hear" the strobes when I pull back the throttle for landing. I thought about doing the noise filter fix, but the interference is only really noticeable without music playing. When I don't want audio, I just turn off the input into my headset. If it matters, I have a 912ULS and a Pilot intercom hooked up directly to an iCom A24 radio.

Perhaps this would bother me more if I didn't have a Jeep that requires the stereo up so that you're not bothered by the tire noise and suspension squeaks!

Murphy