Ray,

I have seen this multiple times. I've seen very large swings in freq and
when the problem was fixed, the xponder was back where it needed to be.

The cause of the frequency shift should be fixed, not adjusting the
radio to compensate for it.
It could be a bad connector or a corroded antenna mount.
If you fix it right, then you should be trouble free for the next
inspection.

Dave




Ray Godwin wrote:

I just had a VFR Cert. done and the avionics shop said that the antenna
of coax was causting the frequency of the transponder to be out of
limits. Of coarse they had to bench adjust the frequency of the
transponder to compensate. Has anyone ever had this problem before?
Thanks,
Ray