On Saturday, June 3, 2017 at 5:34:46 AM UTC-7, Echo wrote:
Installed my transponder this off season, passed the transponder check to make it legal. First flight with it yesterday. Called the local controlling agency to check it out. They had nothing on me, but they did once I cycled the transponder off and back on. I then realized that where the "ALT" is indicated on the lower right of the screen with the little airplane symbol was actually just 3 dashes instead. Multiple times in flight I noticed it kicked off to the dashes, and I wasn't broadcasting. It seems a reboot worked, but not for long. Running it with a premade wiring harness and L2 antenna, dual LiPo batteries. Anyone have any ideas?

Jordan
ASW20

The only thing in the manual that addresses this is this:

Warning Messages
If the transponder detects a problem, the screen will indicate WARNING and a brief statement of the problem. Depending on the nature of the problem, your transponder may not be replying to interrogations. Note the message on the screen and pass that information to your avionics maintenance organisation. Press ENT to clear the message; if the fault is still present the message will reappear.

My guess is that the transponder detected an impedance mismatch with the antenna and shut down transmissions to protect itself. A mismatch could be the result of a damaged coax (there may be no external signs of damage). Let us know what Trig says.

Tom