[647jc]

I have just started flight tests and I think my XPNDR is not functioning. I'm assuming the indicator next to the numberic #7 on the face of the unit should flash when the unit is interrogated and responds. The manual says nothing about the indicator and I have not had time to check with a tower to see if the unit is responding. I have the airplane down right now for a 5 hr check and before I start crawling around under the panel checking wiring I thought I would first make sure the thing next to the #7 on the face plate is in fact an indicator and it should be flashing when pinged. Everthing else rearding the unit appears to be correct.

I've also included a schematic of my wiring below, anyone see anything that does not appear correct?

 

[sjhurlbut]

The "indicator" that you're talking about is not an indicator at all. Its a light detector for auto dimming. To see if its working you should get a flashing R with a circle around it in the actual bottom left face of the transponder display meaning it is replying to a hit. OR just call ATC and ask for a code.

Steve
RV7A

 

[RBrinkerhoff]

When the unit is on and set to ALT, The symbol "ALT" should be shown in the left mid portion of the indicator. As the unit responds to an interigation, an hightlighted "R" should appear below the ALT symbol. If this is not occuring, I would first check the antenna and associated connectors.

Richard

 

[647jc]

Great!

Thanks to both responders. I had thought the photo cell for diming or switching from day to night mode was located in the upper left portion of the display, after just checking I apparently confused it with my SL30 radio. Chances are the GTX is working properly and I just didn't look for the right indication. A lot of things to test / check during the first few hours of flight and I just haven't gotten around to them all. At least now I can button up the airplane and get back into the air without first crawling around verifying the GTX wiring and antenna which I now think is OK.