I had the same problem with mine (KT76 with Terra encoder). As the other
posters suggested, the problem was with my encoder (Would not warm up)
"Bob Fry" wrote in message
...
"JB" == Jimmy B writes:
JB Has anyone see this before?

Others have mentioned the encoder. When I rented planes several had
the same problem you're describing.

The encoder on my Aircoupe went out on a cross-country, I noticed it
when Seattle Approach told me. The fix was very easy, buy another
encoder and have an avionics tech install and test it.