On Feb 20, 10:10*am, kd6veb wrote:
Hi Gang
* This thread prompted me to think as to how the MXR unit ignores my
transponder in my glider which is being pinged regularly where I fly?

As Darryl has explained the MRX is designed to distinguish between
your own transponder and the transponders of threat aircraft.

However in my PA-28 the MRX seems to get confused at least once on
every flight, usually about 10 minutes after takeoff. What happens is
that I see a target rapidly converging on me in both altitude and
distance then it stays about 0.6 miles from me at the same altitude.
If I cycle power on the MRX the target, which was my transponder, goes
away usually for the rest of the flight.

I adjusted the suppression level but still have not eliminated the
problem. I know that my transponder is a bit low on power until it
has been responding for about 10 minutes and I assume this is
contributing to the problem. It's a bit puzzling that, before the
spurious target converges on me, the MRX reports my own transponder
squawk and pressure altitude correctly. This would seem to imply that
the spurious converging target is not the first acquisition of my
transponder signal.

I have not sent the MRX back to ZAON for testing since I thought the
problem may have been caused by a detuned aircraft transponder
antenna. It is missing tip ball. After a bit of investigation I was
able to obtain the manufacturer's drawing of the tip ball and found it
was made of acrylic, not brass as I had assumed, so it would not have
been a factor.

Substitution of a different KT 76A would be the next thing to try but
I don't have a spare just lying around

Andy