View Single Post
  #4  
Old April 5th 11, 02:43 PM posted to rec.aviation.soaring
Ramy
external usenet poster
 
Posts: 746
Default MRX PCAS displays wrong code and altitude for my transponder

On Apr 5, 10:21*am, Andy wrote:
On Apr 4, 10:19*pm, 5Z wrote:

The MRX is mounted on top of the glare shield and the Becker is driving a L2 antenna mounted in the nose of my ASH-26E, just forward of the rudder pedals.


When I squawk 1201, the MRX shows 1236 (or other 12xx code) and the altitude is about 500' lower than what's on the Becker.


Are the antennas too close to each other?


I'm thinking of putting a sheet of foil just under the MRX and forward to provide some shielding from the xponder antenna. *Since the MRX is attached to the glare shield, which in turn is attached to the canopy, I could also install a length of coax and place the MRX antenna by my shoulder on the canopy rail.


Thoughts?


-Tom


First check that the internal baro sensor is set correctly.
Calibration instruction are in the manual. *Then you can try adjusting
the suppression level. * It's on page 2 on the calibration menus.
Call ZAON product support for help with that.

A local ASW-27 pilot has a TT21 with antenna mounted near the rudder
pedals and I have not heard him complain of problems with his MRX.

If in doubt send it back for calibration *Mine had degraded to the
point it was useless and ZAON fixed it for me at no charge.

Andy


Folks, the MRX often displays wrong code and occasionally wrong
altitude. This is a common issue with this unit and nothing can be be
done about it. I recalibrated the threshold and returned my unit twice
complaining about it until they admitted this is normal due to design
limitations. The code and altitude usually gets messed up when flying
close to another glider and may stay wrong for sometime after that.
Just ignore the code. As for the altitude error assume a 500 feet
error so always search above and below you when it shows less than 500
feet difference.
My above comments are based on 5 years using this unit, multiple
correspondents with the factory and other pilots experience.

Ramy