Peter,
How about replacing it with a Garmin GTX 320A with an adapter for
~$1300? I will do that if/when my tube goes.

I'm having an extended "warming" problem with my KT76C where it takes
sometimes 10-15 minutes for it to respond to ATC. I brought it in for a
$250 checkup and it passed with flying colors. When I inquired about
the tube maybe needing replacement my avionics guy said it was around
$500-$700 to replace the tube.
However, he said that the antenna was most likely the culprit and that
I should replace the small flagpole type with a blade first. Makes
sense but I'm not so sure an antenna problem will give me the same
symptoms so I'm prepping myself for a unit replacement.

Marco


Peter R. wrote:
A friend just let me know that his relatively new (four year old) Bendix
King KT76C transponder failed the mode C biennial test.

When the unit was sent in for a $250 troubleshooting (Duncan, I believe,
not Honeywell) analysis, he was told that his unit required a $1,700 repair
to replace the failed "tube" inside.

It looks as if a used KT76C is selling these days for US $1,700 to &1,900.
Does he really have no option but to throw this thing in the garbage?

--
Peter