"John Giddy" wrote in message
...
On 9 Mar 2005 17:30:05 -0800, John wrote:

I found the source of the problem...I have also installed a B40 Digital
Averager Display (DAD). Basically, if this is connected to the B40, I
get the big vario deflection during transmit. Once I disconnected it,
the B40 was virtually unaffected by the transmit. I connected and
disconnected it a few times to prove it was the cause. The DAD consists
of 4 twisted wires in an unshielded pvc jacket. I ran the its wires
only about 4 inches over to the back of the vario. I guess I'll have to
talk to the manufacturer about it or just return the DAD. I thought it
would be a "nice to have" since I was already in the panel doing work.

I would still look at the antenna connection as suggested by Eric
Greenwell. It seems to me that there is too much RF energy floating
around behind your panel. Maybe a bad shield connection at either end
of the coax cable ? An SWR test would pick this up.
AFAIK, Mike Borgelt's products are fairly immune to stray RF, but if
there is a strong field strength, it will still affect the vario.
Cheers, John G.

I agree with Eric and John. There has to be some problem with the antenna
which will degrade the performance of your radio.

There are a LOT of B40's in use and this is the first RF interference
problem I have heard of. The B40/DAD issue is more likely a symptom and not
the source of your problem.

I'd start with the BNC antenna cable connector on the back of the
transceiver. My guess is that the shield is disconnected or some corrosion
has formed on the connector parts.

Bill Daniels