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Jun 4th, 2018 at 8:57am

MileHighDynon   Offline
New Member

Gender: male
Posts: 3
I'm trying to figure out my transponder issues. Any basic info would be helpful, along with guesses on diagnostics.

I have a 2011 CTLS with twin Skyview PDFs. The transponder is hidden behind right PDF (All transponder controls are accessed through the PDFs).

Recently, the tower has been telling me that my transponder is intermittent. Sometimes, they see only my "target" with no altitude. At other times they see nothing.

If I recycle the transponder (by pulling breaker and re-setting it), transponder comes back online but eventually it fails again. The entire time, I'm getting no transponder error on the PDF. The display shows it is working (except when I pull the breaker).

The controller said it goes in an out, on downwind, then back on again in the base turn. They said it seemed like a "signal problem".

I checked antenna connection. It appears to be secure.   

What would make the transponder appear intermittently? While appearing "normal" on my PDF displays? Then coming back on when I recycle, only to fail again?

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Reply #1 - Jun 4th, 2018 at 1:41pm

RayInGA   Offline
I love aviation!
Richmond Hill, GA

Gender: male
Posts: 579
I agree with the tower's guess. Your Dynon system sees the transponder but its output, which it doesn't see, is weak or intermittent. Look for a bad coax crimp or pin that isn't all the way seated in the BNC or TNC.

Also, disconnect both ends and check for continuity between the pin and connector shell. There should be none (OL).

« Last Edit: Jun 4th, 2018 at 1:45pm by RayInGA »  

Ray Eaker
RV-7A flying since 27 Jan 2017
Dual Skyview 1000T with all available Dynon VFR goodies
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Reply #2 - Jun 4th, 2018 at 5:12pm

JakeJ   Offline

Gender: male
Posts: 1585
FWIW - I’ve seen that happen with the TNC connector being screwed on, but not tight enough, at the Transponder end.
« Last Edit: Jun 4th, 2018 at 5:13pm by JakeJ »  
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