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1. 10:48 AM - Garmin 250XL Squelch Issue (Robin Hou)
2. 11:27 AM - Garmin 250XL Squelch Issue (Bitterlich, Mark G CIV NAVAIR, WD)
3. 12:29 PM - Re: Garmin 250XL Squelch Issue (Robin Hou)
Message 1
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| Subject: | Garmin 250XL Squelch Issue |
I have a Garmin GNC 250XL in my CJ-6. I fly mostly in formation with others. There
are 2 CJ's that I fly with which have Icom IC-A200 radio installed in them.
When I fly with Icom IC-A200 equipped plane in formation, the transmission from
Icom would trip my 250XL squelch which requires resetting my auto-squelch by
pressing SQ button. Sometimes it is so bad that I cannot hear any transmission
for the rest of the flight even after I have reset the SQ button multiple times.
When the problem occurred, the 250XL continued to transmit fine but I heard
no transmission.
I have no problem flying formation with other planes with non-Icom radios; only
the Icom radios cause this issue. Also no issue with ATC when I am flying solo.
The radio has been bench checked OK.
Any advise on how to pin point the issue is greatly appreciated. Thanks in advance.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=482155#482155
Message 2
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| Subject: | Garmin 250XL Squelch Issue |
Are you saying that when you fly in formation with aircraft using the IC-A200 radio,
that without them ever transmitting to you ... as in they are not talking
or pushing the PTT button..... that as soon as you get close to these aircraft
that you start to hear static in your radio? You say that the Icom would "trip
my 250XL squelch". What exactly does that mean? I grasp what it PROBABLY
means, but I need to know precisely what is going on. As I said, do you start
to hear static noise in your headset, and that you would try to make it stop
by hitting the SQ button? And that even when you got the noise in your headset
to stop making noise, you then could not hear anyone else talk? Please verify
this as correct.
1. Did you have the flight (as in all aircraft in formation) change to a different
frequency and see if it changed what was going on?
2. When it was happening, did you try YOUR radio on a different frequency to see
if you could hear anyone else? As in an ASOS transmission, tower, ground,
ATC, anyone?
What it sounds like ... without test data.... is that the ICOM radios have Local
Oscillator leakage and they are actually radiating enough energy to impact the
radio in your aircraft. The only way to know this for sure is to use a SpecAn
(Spectrum Analyzer) on the offending aircraft radios (the Icom's) and see
what it is for sure. It is important to know that when this happens, do you
experience it only when you are on the same frequency that they are on, or can
you switch to another frequency (with them staying where they were) and then
your radios receiver starts working well again. Then when they switch to your
new frequency, that the problem comes back. Further, that when they turn their
radios completely OFF, that your receiver start working perfectly again.
There are a few things that can cause this to happen but to narrow them down, you
have to be very specific in exactly how this occurs, and then run tests as
noted above. It is possible that if you all try a totally new frequency, well
removed from the one you have been using, this problem might actually disappear.
But ... it also might not... and that is also critical to know.
In the end, you have stumbled on a very rare problem that will more than likely
take some local expertise with the right test equipment to solve. If I could
get my hands on the offending aircraft, using a SpecAn, we could nail this down
very quickly ... but without that, it might prove difficult.
Mark
-----Original Message-----
From: owner-yak-list-server@matronics.com <owner-yak-list-server@matronics.com>
On Behalf Of Robin Hou
Sent: Tuesday, August 07, 2018 1:48 PM
Subject: [Non-DoD Source] Yak-List: Garmin 250XL Squelch Issue
I have a Garmin GNC 250XL in my CJ-6. I fly mostly in formation with others. There
are 2 CJ's that I fly with which have Icom IC-A200 radio installed in them.
When I fly with Icom IC-A200 equipped plane in formation, the transmission from
Icom would trip my 250XL squelch which requires resetting my auto-squelch by
pressing SQ button. Sometimes it is so bad that I cannot hear any transmission
for the rest of the flight even after I have reset the SQ button multiple times.
When the problem occurred, the 250XL continued to transmit fine but I heard
no transmission.
I have no problem flying formation with other planes with non-Icom radios; only
the Icom radios cause this issue. Also no issue with ATC when I am flying solo.
The radio has been bench checked OK.
Any advise on how to pin point the issue is greatly appreciated. Thanks in advance.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=482155#482155
Message 3
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| Subject: | Re: Garmin 250XL Squelch Issue |
Hi Mark,
Sorry, I should have been more clear. I say that the Icom would "trip my 250XL
squelch"; what I mean is when the Icom transmits, my 250XL auto squelch function
would adjust itself to a point that I can no longer hear any transmission from
any radio. It occurred mostly when the Icom equipped plane is flying lead
which requires transmissions lasting for a 30 seconds or so at a time. When the
Icom equipped plane is not lead and stays radio silent, there was no problem.
When the Icom equipped plane is not lead and only does very short transmissions
(i.e. checking in), there is no problem.
Interestingly, my portable radio, which has manual squelch adjustment, could receive
transmission when my 250XL is silent.
You ask 1. Did you have the flight (as in all aircraft in formation) change to
a different frequency and see if it changed what was going on? Yes, the issue
had occurred on 121.20, 123.30, 135.95 & 135.97.
You ask 2. When it was happening, did you try YOUR radio on a different frequency
to see if you could hear anyone else? As in an ASOS transmission, tower,
ground, ATC, anyone? Yes, changing frequency on my 250XL does not restore its
ability to receive transmission. When the issue occurred in the beginning of
a flight, I could resolve the issue by pressing SQ; however, after about 10 to
15 minutes, pressing the SQ does nothing.
Your help is greatly appreciated.
Robin
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=482160#482160
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