Thanks all for your advice, I also had a problem once or twice with
this transponder on the last digit not showing correctly on their
side. ATC asked to confirm my squawk a couple times, and then I
suppose he got a supervisor who said "the last digit of your
transponder...what does it read?" He told me to rotate the knob around
a few times, which fixed it. The airplane was set on 1200 and never
changed for a decade, maybe it just needed to be cycled some

Dave Butler wrote:
John R. Copeland wrote:
That is correct - there's no adjustment on the encoder.
Your encoder reports density altitude to ATC.

Make that "pressure altitude".