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whd721

Well Known Member
My GNC 250 XL (GPS/COMM) on com1 is weak and "staticy". You can hear a weak audio and have intermediate transmit . Com2 a KX 125 (NAC/COM) on com2 works great.

The audio panel is a GTX 327.

Since the com2 works, I am assuming that the headset, jacks and GTX 327 are working.

The Garmin flat rate on the GNC 250 XL is $550.

Any ideas or suggestions before I pay Garmin?
 
Different antennas?

If so, check the antenna connection for the week com.

I had a problem and the fix was simple. Just remove one antenna screw at a time and spin your deburring tool in the screw hole. You want to remove any oxidation in there and put the screw back on. It turns out those screws ground the antenna to the aircraft.
 
First thing to check is the antenna connections both at the radio and the antenna. A loose or bad ground connection will absolutely cause these conditions.

BTW, the GTX 327 in a transponder.
 
See if you can find someone local with the same radio. Test theirs in your plane and your in their plane and you will know if it's the radio or the installation. I'm guessing the antenna cable, but easy tests first, is say.
 
I troubleshot something like this recently. Can you switch the antennas to see if the behavior still effects the same radio? This problem was weak transmission and some intermittent static. I had checked "everything". Then I realized that I did not check the brand new pre-made short com cable that came with my SL-30. My problem turned out to be this cable. The 90-degree BNC connector that connects to the back of the radio tray had a single stray strand of the core wire that was separated from the rest and was grounding on the connector housing. Once I fixed that, everything works great. Good luck.
 
Thanks for the tips guys. I will swap antennas to check if that results in a significant change. A logical point to investigate.

Mel good catch, I transposed numbers GMA 340 audio GTX 327 trans.
 
Another DUH moment!

With the suggestion to check antennas for grounding, I went to the hangar to check out the potential issues.

I had the lower com antenna installed years ago. It was the easiest to reach, I disconnected the coax BNC connector and wiggled the antenna then reconnected the BNC, but it felt funny, I pulled on the coax and out it came leaving the BNC connector on the antenna.

That might be the problem.

The BNC connector is a Garmin 330-00087-00 that screws together to lock on the coax. Can it be replaced with the crimp on BNC connectors that Stein sells?

The center conductor appears to be crimped on so I can't trim 1/2"off and re terminate. I straightened the shield wires as best I could and reassembled the BNC connector. Audio had cleared up.
 
Great job. You found it quickly. Yes, you can replace with a "crimped" BNC.
 
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