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  #11  
Old 05-19-2020, 09:25 PM
jbDC9 jbDC9 is offline
 
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Location: Houston, TX
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Quote:
Originally Posted by g3xpert View Post
Hey John,

So when you are sitting in the hangar, you hear the audio interference, and upon removing the audio line from the 660, the noise disappears completely, until you start the engine, when the same noise shows back up?

When you disconnected the audio line, did you remove the wiring completely? What audio panel are you using?
Thanks Justin,

Yep, in the hangar, electrics powered up and headset on, there was lots of static type noise, snap-crackle-pop. I then pulled the 660 audio (Left channel) wire from the audio panel and all went blissfully quiet... but upon starting the engine, the noise was back. It wasn't quite as bad as before, but still annoying. Powering up for taxi/takeoff, the noise amped up a bit.

I don't have a true audio panel, but an AP-60 Audio Mixer linked below; it's a mono unit, so I just have the 660 audio Left channel to the AP-60, R is unused, Common is grounded at the AP-60. I didn't remove all the audio wiring, just pulled the L channel wire and capped it.
http://www.fdatasystems.com/ap-60-audio-mixer

If it's the power lead, does that mean I gotta run a shielded power line now? What a bummer this is considering the old 496 in an identical installation was dead quiet compared to the 660...

Thanks!
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  #12  
Old 05-20-2020, 12:05 AM
jliltd jliltd is offline
 
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John. Have you tried attaching the bare wire cable shielding to its own ground wire? That's what Garmin does internally in their cables at the bare wire end. But if you cut the length of the Garmin cable down the connection of the shield to the ground wire is lost. So solder a jumper wire to the shielding and then connect it to the ground wire. If you already tried this and it still gives noise try connecting the shield to the DSub connector backshell on the audio mixer. If your backshell doesn't have a convenient location for this then put a ring terminal on the shield jumper wire the same size as the retaining screws on the Dsub connector and sandwich it between the connector and audio mixer using one of the thumbscrews as you attach the connector. If you disassemble the backshell you can also put the ring terminal on the top of the same mounting screw which is a better long-term solution since it stays together without confusing the next guy.

Also, if you have been trying different connections to the shielding already and haven't tried it without the shield "open" meaning not connected to anything then by all means try that too. I had that happen one time in an airplane on a LEMO plug installation. Nothing worked well until I clipped the shield drain wire. Go figure.

Jim
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Last edited by jliltd : 05-20-2020 at 12:14 AM.
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  #13  
Old 05-20-2020, 05:02 AM
Mich48041 Mich48041 is offline
 
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Try installing a ground loop isolator between the GPS and your audio panel.
Van's supplied one with the original D180 kit.
Search Van's Aircraft store for "AV GROUND LOOP ISO"
Or perhaps eBay item number:151617844291 or Amazon
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Last edited by Mich48041 : 05-20-2020 at 05:47 AM. Reason: Added Amazon link
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  #14  
Old 05-20-2020, 05:30 AM
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Piper J3 Piper J3 is offline
 
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This is an interesting thread. I can “hear” engine electric noise. I bought new hearing aids that switch user programs with my cell phone. One program turns on a “telecoil” which is normally used with an old-style telephone handset. The telecoil receives induced EMF and converts it into audible sound. Works really good. Anyway, with the telecoil, I can hear engine and electrical generated noise and I can tell you the 912 is going-to-town. Same thing with my car. I drive a hybrid Prius and it makes all kinds of weird electrical noise.

Just thought I’d liven up everybody’s day. Maybe I should hire out?

I talk about using telecoil hearing aid in conjunction with ANR aviation headset here… http://www.vansairforce.com/communit...ING+AID&page=5
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  #15  
Old 05-20-2020, 08:08 AM
jbDC9 jbDC9 is offline
 
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Quote:
Originally Posted by Piper J3 View Post
This is an interesting thread. I can “hear” engine electric noise. I bought new hearing aids that switch user programs with my cell phone. One program turns on a “telecoil” which is normally used with an old-style telephone handset. The telecoil receives induced EMF and converts it into audible sound. Works really good. Anyway, with the telecoil, I can hear engine and electrical generated noise and I can tell you the 912 is going-to-town. Same thing with my car. I drive a hybrid Prius and it makes all kinds of weird electrical noise.

Just thought I’d liven up everybody’s day. Maybe I should hire out?
Ha! Funny... heck, I’m half deaf already with tinnitus and loss on my right ear, but with my Lightspeed ANRs on the noise is just annoying. Looks like I need to order up some more shielded wire and go to town on this thing...
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  #16  
Old 05-20-2020, 10:26 AM
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g3xpert g3xpert is offline
 
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Quote:
Originally Posted by jbDC9 View Post
Thanks Justin,

Yep, in the hangar, electrics powered up and headset on, there was lots of static type noise, snap-crackle-pop. I then pulled the 660 audio (Left channel) wire from the audio panel and all went blissfully quiet... but upon starting the engine, the noise was back. It wasn't quite as bad as before, but still annoying. Powering up for taxi/takeoff, the noise amped up a bit.

I don't have a true audio panel, but an AP-60 Audio Mixer linked below; it's a mono unit, so I just have the 660 audio Left channel to the AP-60, R is unused, Common is grounded at the AP-60. I didn't remove all the audio wiring, just pulled the L channel wire and capped it.
http://www.fdatasystems.com/ap-60-audio-mixer

If it's the power lead, does that mean I gotta run a shielded power line now? What a bummer this is considering the old 496 in an identical installation was dead quiet compared to the 660...

Thanks!
Which input on the AP-60 are you using?

If the common is still grounded at the AP-60, remove that line and see if anything changes, to try to narrow things down a bit.

What are the alert and message volumes set to on the Aera 660? If they are set low, and the alert input gain on the AP-60 is set high, that could exacerbate any audio interference issues. Ideally you want the 660 volume set fairly high, with the audio panel alert input volume set lower.

Thanks,

Justin
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  #17  
Old 05-31-2020, 01:48 PM
jliltd jliltd is offline
 
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Quote:
Originally Posted by jliltd View Post
...If your backshell doesn't have a convenient location for this then put a ring terminal on the shield jumper wire the same size as the retaining screws on the Dsub connector and sandwich it between the connector and audio mixer using one of the thumbscrews as you attach the connector. If you disassemble the backshell you can also put the ring terminal on the top of the same mounting screw which is a better long-term solution since it stays together without confusing the next guy.
Here is what I am talking about.....

http://www.vansairforce.com/communit...16#post1435016
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