"Jay Honeck" wrote in message
news:Tjy5b.345829$o%2.158911@sccrnsc02...
The third digit on my formerly bullet-proof Narco AT-50 transponder has
suddenly started displaying incorrectly for ATC. Specifically, it seems
to
be showing as a "4" on their screens, regardless of what we dial it to in
the plane. Thus, instead of squawking "1200" when we're VFR, we're
squawking "1240"...

What could cause this? Any recommendations on repair versus replacement?

Thanks!
--

What a coincidence. My AT 150 pulled this stunt at the beginning of a trip
from Texas to Las Vegas about a week ago. In my case, the third digit
flipped back and forth between 5 and 1. The bad news is that it will likely
get worse, to the point where ATC can only see you part of the time. That
caused me to rethink flying into the very busy Las Vegas area, opting
instead to park it at Kingman, AZ. At least we got to see the Hoover Dam
again.

Anyway, the good news is that mine was fixed locally for $65.00. It was
described as being an "adjustment", but I forget what was adjusted. I could
look at the invoice to refresh my memory. While I'd love a pushbutton
Garmin, I'm too cheap to toss a fixable unit.

To save you a phone call, Narco factory service is $95.00 per hour plus
parts. 2 to 3 week turnaround. They have a factory reconditioned exchange
program for $595.00. Also a 2 to 3 week turnaround. I think there are
issues with replacing an AT 50 with a 150. Something about needing a 150R.

Let me know if you want details about where I got mine done.

Dick Meade