Transponder intermittent

drgwentzel

drgwentzel

Pre-takeoff checklist
Joined
Sep 7, 2008
Messages
284
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NJ
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Kobra
Flyers,

This Saturday I was flying back from Ocean City, MD when ATC (Both Atlantic City and Dover) told me they were not picking up my transponder (King KT-76C) or that I was coming in intermittently (more off than on).

Of course I recycled the unit, made sure it was on ALT and checked the switch for the Encoder to make sure it was set to On. It was and no joy.

Anyone ever have this problem? What could it be. How about the connections from the unit to the antenna?

Gene
 
The first thing you should try is to clean the antenna. Usually the antenna is on the belly and gets covered with oil. For each plane that I fly, I check the transponder antenna as part of my pre-flight.
 
MikePapa said:
The first thing you should try is to clean the antenna. Usually the antenna is on the belly and gets covered with oil. For each plane that I fly, I check the transponder antenna as part of my pre-flight.
Click to expand...

That may help and it's easy to try but chances are the transmit frequency is out of tolerance. Any good avionics shop can check and adjust this.
 
Gene,

Just had the same thing with Dover last week. Recycled twice nothing, landed at 33N to meet a friend, checked the breaker again and launched for another check. Dover had us with no problems this time, however, I did notice that our light was not blinking at all. The club Archer I fly was checked out at Red Eagle Avionics. Not sure what the outcome was, but I think they sent it out for repair. I was cleaning out a few of my things and saw an envelope (invoice) on the seat.

I'm out of the club plane and heading to Texas this morning to pick up our "new to us" 80 Sundowner. The Archer has an opening if anyone is interested.
 
My connectors needed to be cleaned. Fixed my issue.
 
MikePapa said:
The first thing you should try is to clean the antenna. Usually the antenna is on the belly and gets covered with oil. For each plane that I fly, I check the transponder antenna as part of my pre-flight.
Click to expand...

Well I cleaned the antenna today and took it north to KWRI and they picked up my transponder. I turned to the south and headed to KACY and they too saw the transponder.

Maybe the cleaning helped, maybe it's an intermitted problem that will rear it head again and maybe shutting the engine down and taking all power away "rebooted" it. Who knows but I appreciate everyone's input

The only bad news is that I had my heart set on a new Garmin GTX330.

Gene - N14
Cardinal RG - N8207G
 
gismo said:
That may help and it's easy to try but chances are the transmit frequency is out of tolerance. Any good avionics shop can check and adjust this.
Click to expand...

That may be, but I always like to check the easiest and cheapest things first.
 
It'll fail again the next time you're getting near the ADIZ. Sorry, but you need to go out and buy a GTX330 right now. Anything else is just wasting time and money and is likely to get you shot down.

:) :) :)
 
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