Greg Farris wrote:

Is it possible that this is the case with the transponder? Anyone know of a
tube transponder?

Yeah, KT76 and lots of others. Microwave tubes are still in use.
Actually the biggest thing you want to use STANDBY for is many encoders
need preheat on their pressure sensing element.

I always learned that you are to use only two modes on the transponder -
"Standby" and "ALT" (or mode "C"). ON and OFF were never to be selected.

Fine if you have a avionics master, but I'd tell you to shut your
transponder off while cranking the engine. Further ON (or Mode A)
is required when ATC asks you to stop altitude squawk (has happened
to me).


I was also instructed to IDENT after acknowledging a transponder code change,
even if not specifically requested to do so by ATC. The reasoning was that
they will see your ident immediately, while it may take them up to a minute
to see your code change.

Not only is this the wrong procedure, it's bull****. The IDENT and the
code
are transmitted with the same frequency.