On Dec 16, 12:53*pm, Bob Kuykendall wrote:
On Dec 15, 7:46*am, Andy wrote:

...I'm quite sensitive to this at the moment as my airplane has developed
a problem that causes the mode C report to sometimes be thousands of
feet in error until the transponder or encoder warm up.

Check the encoder manual to see if the encoder has a built-in heating
coil (many do). If so, also check that it is getting power.

Thanks, Bob K.

The ACK-30 around room temperature should draw around 9mA/12V once in
steady state. Throw it in your freezer in a plastic bag and get it
really cold, with the heater warming up it should draw about 400mA/12V
(for ~minute or so).

Darryl