rainbow462 wrote:Thanks for the replies
I'm observing the FL from the transponder screen. Also when I check back FR24 it matches what I saw in flight. Finally using getyourwings software and a polotaware base station I can it is receiving the ADBS signal and the altitude is significantly out e.g. -600'
I'm assuming the TRT800H has a built in encoder.
The static port at the back is not connected to the altimeter/external port and is just is open in the back of the dashboard
A bit late to this but I had an issue with my TRT800H recently (though nothing to do with any fault on the unit itself). After climbing to 6000ft, and after descending to 1600ft, it was still indicating FL034 (which worried the local ATC), and was showing FL019 on landing at near sea level. I have no idea of whether it kept up with the ascent rate or whether it achieved an output of the max altitude I reached (I wasn't up there for longer than a minute). I assumed a blockage and pulled off the static tube from the back of the transponder, by that time it was still showing an output of FL009 and pulling the pipe made no difference. I have since removed the transponder and found a tiny piece of a translucent film and a tiny amount of waxy looking residue (yes, like earwax) blocking the port at the back of the unit.
I have now cleaned it out and hopefully it's cured (not yet refitted).