SL40 continuously breaking squelch

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Lindberg

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Lindberg
My new-to-me plane has an SL40 transceiver, and when in the air (seems to be only in the air) it continuously breaks squelch on the receive side. I do not think it's the intercom or mic side because adjusting the intercom squelch or covering the mic has no effect, and when it's happening, I can sometimes here very faint transmissions.

I have the owner's manual, but can't find anything about an adjustment. Is there a (possibly hidden) way to adjust the sensitivity?
 
I had a similar issue when I ran the SL40. On mine it ended up being related to the 430. I turned off the 430 and the SL40 quieted down. Maybe it was my installation. On my little Lancair, there isnt very much room to properly separate antennas. The install manual below speaks to minimum separation from other antennas including GPS antennas.
In any case, the SL40 has a setup menu where you will find squelch. See page 12 of the install manual here:
http://11hc.44rf.com/manuals/avionics-instruments/sl40/SL40_Install_Manual.pdf
there is also a pilot guide here:
https://takewingaviation.com/wp-content/uploads/2017/02/SL40Comm_UserGuide.pdf
 
Pull the volume knob out-that's the squelch control
 
murphey said:
Pull the volume knob out-that's the squelch control
Click to expand...
The SL40 has automatic squelch. Pulling the volume knob just opens the squelch.
Also, for what its worth, I believe the SL40 is sensitive to RF noise. When I removed the SL40 and installed the Garmin GTR 200 I reused all the SL40 wiring and antenna. The GTR 200 doesn't break squelch anywhere near as much as the SL40 did. I tried turning down the SL40 squelch and ended up not hearing transmissions that I should have been able to hear. All likely related to my compact install but better with the GTR 200.
 
FORANE said:
I had a similar issue when I ran the SL40. On mine it ended up being related to the 430. I turned off the 430 and the SL40 quieted down. Maybe it was my installation. On my little Lancair, there isnt very much room to properly separate antennas. The install manual below speaks to minimum separation from other antennas including GPS antennas.
In any case, the SL40 has a setup menu where you will find squelch. See page 12 of the install manual here:
http://11hc.44rf.com/manuals/avionics-instruments/sl40/SL40_Install_Manual.pdf
there is also a pilot guide here:
https://takewingaviation.com/wp-content/uploads/2017/02/SL40Comm_UserGuide.pdf
Click to expand...
Thanks. That installation guide is exactly what I needed. It does have a Garmin 496 (which suddenly can't find the satellites) so I'll try turning that off and see if it makes a difference.
 
Had a similar issue with my SL50. It was just a matter of finding the sweet spot on the squelch. It's been working great for almost 12 years now.
 
Also try switching to each mag briefly to see if the noise is from the ignition system.
 
We recently figured out that the ELT antenna was re-radiating a signal that was causing the garmin radio to break squelch. Easy to check once we knew where to troubleshoot, simply temporarily disconnected the ELT antenna and the issue went away.

My avionics guy just told me that there may be a different ELT antenna that can be installed to permanently resolve the issue.

Brian
 
Resurrecting my own thread. We never did get the problem resolved, and I didn't want to turn the squelch up too high and miss calls, so we just lived with it until now. Took it to an avionics shop, and they bench tested it and say there's a problem with the radio. The solution is to send it to Garmin with an $800 check. Does anyone have suggestions for repair other than sending it back to the factory? There have to be cheaper options....
 
Garmin is fascist when it comes to just about any non-trivial service.

However, note that you don't want to send it to normal Garmin service (Olathe, KS). This unit goes to the ex-Apollo guys in Salem. However, before you do that, call them up and ask them if they have any ideas. I've found Salem's tech support to be one of the few people in Garmin worth a plug nickel.
 
flyingron said:
Garmin is fascist when it comes to just about any non-trivial service.

However, note that you don't want to send it to normal Garmin service (Olathe, KS). This unit goes to the ex-Apollo guys in Salem. However, before you do that, call them up and ask them if they have any ideas. I've found Salem's tech support to be one of the few people in Garmin worth a plug nickel.
Click to expand...
Do you know how I would get in touch with them in particular?
 
Want a cheap used one? I'm replacing mine with a GTR200B

Sent from my Pixel 3 using Tapatalk
 
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