Bendix KT76C transponder requires major repair: Options?

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

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

Oh crap, I just realized that the "KT76C" is an entirely different
animal so my previous post is null and void. Sorry Peter. Of course,
I'm thinking of the KT76A.

Marco

Marco Leon wrote:
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

Marco Leon wrote:

Oh crap, I just realized that the "KT76C" is an entirely different
animal so my previous post is null and void. Sorry Peter. Of course,
I'm thinking of the KT76A.

No problem! With all of these acronyms, I am certainly not immune to
mixing them up, either.


--
Peter

Marco Leon wrote:

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


Could be the encoder warm-up. The transponder won't reply mode C until
the encoder warms up. Some of them take 10 minutes or more to come up
to temperature.

Narco makes the AT165 in a version that is a slide-in replacement for
the KT-76. I've got an AT165 in my plane, and I like it. It is has a
solid state transmitter, so there are no worries about a tube wearing
out. The interogation decode and reply generation is all digitally
timed from a quartz crystal, so unlike older transponders it also will
not go out of calibration.

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?


Garmin makes an adapter that will retrofit their transponders into
a KT-76(a/C) bay.

Ray Andraka wrote:

Could be the encoder warm-up. The transponder won't reply mode C until
the encoder warms up. Some of them take 10 minutes or more to come up
to temperature.

Now THAT's interesting. Does anyone know if there's a bench check for
the encoder itself? I'm surprised that the avionics shop didn't suggest
the encoder as being the culprit. Is it common?

Marco

Marco Leon wrote:
Ray Andraka wrote:

Could be the encoder warm-up. The transponder won't reply mode C until
the encoder warms up. Some of them take 10 minutes or more to come up
to temperature.


Now THAT's interesting. Does anyone know if there's a bench check for
the encoder itself? I'm surprised that the avionics shop didn't suggest
the encoder as being the culprit. Is it common?

Marco

I know it takes my encoder about 7 minutes to warm up. It is connected
to my GPS and I get "No Altitude" until it does. The transponder will
have its own "encoder" within it. It may also take awhile to warm. I
have the KT78. It would be nice if there was a little ready light.

--

Regards, Ross
C-172F 180HP
KSWI

The 76C has an altitude display so you can see when this
happens. Bill Hale

Ross Richardson wrote:
Marco Leon wrote:
Ray Andraka wrote:

Could be the encoder warm-up. The transponder won't reply mode C until
the encoder warms up. Some of them take 10 minutes or more to come up
to temperature.


Now THAT's interesting. Does anyone know if there's a bench check for
the encoder itself? I'm surprised that the avionics shop didn't suggest
the encoder as being the culprit. Is it common?

Marco

I know it takes my encoder about 7 minutes to warm up. It is connected
to my GPS and I get "No Altitude" until it does. The transponder will
have its own "encoder" within it. It may also take awhile to warm. I
have the KT78. It would be nice if there was a little ready light.

--

Regards, Ross
C-172F 180HP
KSWI

wrote:
The 76C has an altitude display so you can see when this
happens. Bill Hale

Ross Richardson wrote:

Marco Leon wrote:

Ray Andraka wrote:


Could be the encoder warm-up. The transponder won't reply mode C until
the encoder warms up. Some of them take 10 minutes or more to come up
to temperature.


Now THAT's interesting. Does anyone know if there's a bench check for
the encoder itself? I'm surprised that the avionics shop didn't suggest
the encoder as being the culprit. Is it common?

Marco


I know it takes my encoder about 7 minutes to warm up. It is connected
to my GPS and I get "No Altitude" until it does. The transponder will
have its own "encoder" within it. It may also take awhile to warm. I
have the KT78. It would be nice if there was a little ready light.

--

Regards, Ross
C-172F 180HP
KSWI


That's nice

--

Regards, Ross
C-172F 180HP
KSWI