SkyBeacon gotcha

[Rich]

A colleague here in our EAA chapter had a problem with ATC because his equipment wouldn't stably transmit his assigned code. It would randomly change. He has a GTX327 (as our early DA40's were equipped) and one of the 978UAT SkyBeacons for ADS-B out. He was blaming the GTX, but it turns out it was a problem with the SB.

In a setup like this very common configuration you have the mode C transponder returning a code on 1090 MHz only as a response to a radar interrogation in parallel with an unsolicited transmission on 978 MHz every second or so. The SB is supposed to automatically sense what the transponder is transmitting and use the same squawk code. I've long seen some glaring weaknesses in this approach. You can readily see some yourself.

In any case uAvionics has a procedure to fix this problem. Apparently it's a "secret" part of installation/configuration that isn't normally done, as it's supposedly a rare occurrence and involves placing your aircraft in an on-ground suitable location to complete.

Were you or someone you know to encounter this problem, don't automatically assume the transponder needs repair (as my colleague initially assumed). Contact uAvionics for support.