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  #1  
Old 05-10-2020, 07:28 AM
Mark Dickens's Avatar
Mark Dickens Mark Dickens is offline
 
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Location: Collierville, TN (KFYE)
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Default Static Interference Puzzle

I know we have some "wicked smart" guys here and I ain't one of them, so I am hoping one of them can steer me in a good direction to resolving an intermittent static issue I'm having with both of my comms. Here's the details as I have them now:

1. Static happens intermittently and both comms pick it up as evidenced by the RX symbol illuminating on the comm display. Sometimes only the 650 picks it up and sometimes it's both radios. I can go for as long as an hour without hearing anything and then it starts and might last for a few minutes

2. Turning off equipment one by one, including the alternator, doesn't help.

3. I get it on the ground sometimes so I'm discounting static buildup on the airframe

4. My transmissions are strong.

5. Others flying near me don't hear it

I was planning to pull the floor panel up and check the grounding to the antennas, but beyond that I am at a loss to figure out what to look at. Any ideas? If it matters, the coax is RG-400 and the antennas are Don Pansier's Delta Pop Red Tip. When I installed the radios, I did check the SWR to make sure the connection was good and it was, at least back in the 2015 time frame.

Any and all ideas are welcome....thanks!
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  #2  
Old 05-10-2020, 07:36 AM
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bjdecker bjdecker is offline
 
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Default

The RX indication might be a red-herring, then again, it might not.

I had a similar issue with my first RV-7, with GNS-430W and SL-30 -- every so often I would hear "static" in the headphones. It was especially bad in humid environments (i.e. transitioning from on top of a layer of clouds into the soup)

After many many test flights, turning things on and off, etc. it turned out to be a cracked shoulder washer, bad isolation washer under the co-pilot microphone jack.

This might be your issue -- then again, it might not.

Good luck,

B
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  #3  
Old 05-10-2020, 07:50 AM
Mark Dickens's Avatar
Mark Dickens Mark Dickens is offline
 
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Quote:
Originally Posted by bjdecker View Post
The RX indication might be a red-herring, then again, it might not.

I had a similar issue with my first RV-7, with GNS-430W and SL-30 -- every so often I would hear "static" in the headphones. It was especially bad in humid environments (i.e. transitioning from on top of a layer of clouds into the soup)

After many many test flights, turning things on and off, etc. it turned out to be a cracked shoulder washer, bad isolation washer under the co-pilot microphone jack.

This might be your issue -- then again, it might not.

Good luck,

B
It's on the list to check now, thank you!
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First Flight 11/20/2016
www.marksrv8.com
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  #4  
Old 05-10-2020, 07:56 AM
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Have you tried adjusting the squelch?
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  #5  
Old 05-10-2020, 08:04 AM
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Mark Dickens Mark Dickens is offline
 
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Quote:
Originally Posted by Raymo View Post
Have you tried adjusting the squelch?
Yes, I've done that several times. Weirdly, the Dynon comm does a better job of rejecting it than the 650 does. I've adjusted the squelch on the 650 a couple of time and it improves things a little, but the static still punches through. I have the 650 squelch setting up to almost 70
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www.marksrv8.com

Last edited by Mark Dickens : 05-10-2020 at 08:14 AM.
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  #6  
Old 05-10-2020, 08:05 AM
lr172 lr172 is online now
 
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On a nice VFR day, try turning off both radios and see if the static appears. This will help isolate an intercom/ HS wiring issue, like mentioned above.
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  #7  
Old 05-10-2020, 08:08 AM
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Mark Dickens Mark Dickens is offline
 
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Quote:
Originally Posted by lr172 View Post
On a nice VFR day, try turning off both radios and see if the static appears. This will help isolate an intercom/ HS wiring issue, like mentioned above.
There's one I haven't tried...on the list, thank you!
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www.marksrv8.com
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  #8  
Old 05-10-2020, 08:29 AM
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Walt Walt is offline
 
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USB power plugs are notorious for generating RF noise, the fact that the RX is displayed clearly indicates the noise is be picked up by the radios receivers from something.
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  #9  
Old 05-10-2020, 08:57 AM
Mark Dickens's Avatar
Mark Dickens Mark Dickens is offline
 
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Quote:
Originally Posted by Walt View Post
USB power plugs are notorious for generating RF noise, the fact that the RX is displayed clearly indicates the noise is be picked up by the radios receivers from something.
I've tested that by powering my USB outlet down in flight (I have it on a separate VPX circuit), and it didn't help. The one I have is a Quiet Power QP-100 so I wasn't surprised when powering it off didn't help.
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RV-8 #81077 Super Slow Build
Dynon Skyview HDX, Titan IOX-370, Dual P-Mags, AFP FM200A FI, Whirlwind 200RV CS Prop
First Flight 11/20/2016
www.marksrv8.com
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  #10  
Old 05-10-2020, 09:01 AM
lr172 lr172 is online now
 
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Quote:
Originally Posted by Mark Dickens View Post
There's one I haven't tried...on the list, thank you!
I would also try tuning in an ATIS broadcast for an extended period of time if it turns out to be getting into the RF channel of the radio. This may help to understand more about the intermittent nature so you can do some detective work.

Larry
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