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Squelch breaking on 122.8

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Guitarmaster Veteran

Guitarmaster

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Hopefully someone will have an idea...

Garmin 430W. The squelch breaks constantly but only on 122.8. It has been to the shop and and set-up properly. This is the only frequency that is a problem.
If I touch the radio, it gets better. Doesn't matter if the engines are on or off. Doesn't matter if the other radio equipment is on or off.

it's driving me nuts and I hate that I can't figure it out.

EricJ Grand Master

EricJ

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Does it not matter where you are when it does it?    If it is location dependent, there may be something radiating energy near that freq at that location.   If it is location independent and the shop has already checked the radio out, your airplane may be radiating something spurious near that frequency or there is something in the harness somewhere near that freq.

If you have a ham or other radio-geek friend, ask if they have a spectrum analyzer (they're cheap these days so more people are likely to have them), make a little sniffer antenna or stick a VHF antenna on it and see what you can see.    You may be looking for a pretty low-power signal, but the idea is if there is any consistent energy in that channel that isn't elsewhere it may be responsible for that behavior.   Most spectrum analyzers have hold functions that make this sort of thing reasonably easy, because it's a really common thing to do.  Set the resolution bandwidth to about the channel bandwidth or less (25kHz).   

Another, maybe simpler, thing to try is to start pulling breakers and see if it goes away.   If it stops when you pull the breaker on something, that may be what's causing the interference.

 

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Andy95W Grand Master

Andy95W

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Try adjusting the squelch on the GNS to a point where it stops.  Test fly to ensure the radio still works acceptably at the new squelch level.

I had to do this for the same reason because of 123.0, which is a very common UNICOM frequency where I am.

jaylw314 Grand Master

jaylw314

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The squelch on the 430/530 can be adjusted from the COM SETUP page in configuration mode (hold the ENT button down while turning the unit on).  The fact that it only happens on 122.8, though, makes me wonder like @EricJ if there's something nearby producing noise on that frequency.

Marauder Grand Master

Marauder

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Hopefully someone will have an idea...

Garmin 430W. The squelch breaks constantly but only on 122.8. It has been to the shop and and set-up properly. This is the only frequency that is a problem.
If I touch the radio, it gets better. Doesn't matter if the engines are on or off. Doesn't matter if the other radio equipment is on or off.

it's driving me nuts and I hate that I can't figure it out.


Could it because it is in a 310? Sorry low blow!

The squelch setting is where I would look first. The touching thing could be some weird sort of grounding issue. Did the shop just play with settings or did they reseat it and look at the connections? I would also see if I could find another unit to slide in and see if it is tied to the radio.


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Guitarmaster Veteran

Guitarmaster

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11 hours ago, Marauder said:



The squelch setting is where I would look first. The touching thing could be some weird sort of grounding issue. Did the shop just play with settings or did they reseat it and look at the connections? I would also see if I could find another unit to slide in and see if it is tied to the radio.
 

 

Tried changing the squelch on that freq, but to no avai.  It gets a little better, but not much.

Swapping with someone else's unit is a good idea.

Guitarmaster Veteran

Guitarmaster

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19 hours ago, Andy95W said:

Try adjusting the squelch on the GNS to a point where it stops.  Test fly to ensure the radio still works acceptably at the new squelch level.

I had to do this for the same reason because of 123.0, which is a very common UNICOM frequency where I am.

Tried many settings with the same or slightly better result.  Even with the squelch all the way up, it still breaks repeatedly.  .

takair Grand Master

takair

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Cheap USB chargers can cause peculiar problems.  You say you touch it and the problem goes away?  Stinks of a ground problem.  There are some ground points on the back of the rack that I found degrade over time.  I stopped using them and use a more substantial airframe ground.  It is possible your installer grounded to this same point.  Might check the grounds....

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Guitarmaster Veteran

Guitarmaster

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Got a chance to really mess with it on the way home today. It is in fact breaking squelch on both radios so I'm thinking it's definitely a ground problem.



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Marauder Grand Master

Marauder

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Got a chance to really mess with it on the way home today. It is in fact breaking squelch on both radios so I'm thinking it's definitely a ground problem.



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So it is a 310 problem.


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bradp Grand Master

bradp

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I just got a digital vSWR that got highly rated by the Ham radio nerds. Helped me find that my painted over antenna was a 7.  Took me all of 10 minutes.  Would recommend checking antenna swr, antenna grounds, and then your radio grounds.  Lot of alternator or ignition noise will cause RMI enough to break squelch as well. 

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bradp Grand Master

bradp

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I recall getting an old CB my uncle had given my brother and I.  We got the thing working and started making calls like we had seen in the movies.  Some truckers in I-95 weren’t too appreciative and gave us some lessons in colorful language. 

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bradp Grand Master

bradp

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There was an orphan antenna - at some point in the plane’s history it has 3 coms based on my old audio panel.  I just have the two radios off the two good antennas now - a top and bottom.  

Gary0747 Proficient

Gary0747

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Do you have an old DME?  It is higher frequency so it can’t be a harmonic but those things have been know to emit spurious RF.  I had one in the past that would plot on my storm scope when tuned to a specific VOR.  Make sure it is turned off when trouble shooting. 

  • 1 month later...
Guitarmaster Veteran

Guitarmaster

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Okay, so I found the source of the problem flying home last night. It's the Insight G4 engine monitor believe it or not.
The next question is, why is it happening.
The saga continues.....

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carusoam Grand Master

carusoam

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Matt,

Check In with Marauder’s writing on the subject... As it was his JPI that was doing it...

Might be a similar situation and fix...

Best regards,

-a-

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