"Tauno Voipio" wrote in message
...
The Visitor wrote:
I had a similar problem in mine, then it got worse. Trouble was whenever
it was in the shop, it was working. Finally some guy thought to gently
heat gun the thing and found the failed part. I think it was a capacitor
that when warm, stopped working. It's had other problems too, like that
expensive final transistor going.

Just my experience....

John

skyav8r wrote:
Howdy,
I have an Aeromech 8140B20 encoding altimeter with a KT76 transponder.
Mode C is intermittent with ATC. Is it more than likely this is an
altimeter problem or transponder problem? Sometimes when it is not
reporting, i cycle the transponder off then back on and it starts
reporting again. Thanks in advance,
Brian
Also, sould an aeromech and aerosonic encoding transponder interchange
as far as the connections are concerned?


The KT76 transmitter is a free-running electron-tube
oscillator built into a cavity resonator. The frequency
of the sent signal is dependent on the cavity and
electron tube properties.

When the tube gets old, its properties start drifting
around, and the transmitter frequency follows the
drift. The thing stays on channel for short while
after tuning and then gets off again.

The cure is the change of the transmitter module. The
tube cannot be changed from the cavity alone.

If that were the case he would be having trouble with Mode3 also, and he
only indicated problems with ModeC.