MGL Avionics User Forum

Hello All

About a year ago I installed a Trig TT22 and updated the firmware to be used with my Explorer. All worked fine with the Trig getting its gps info from the EFIS. Now... A couple weeks ago it stopped working and on the diagnostic page it said something about mode S being outdated. Researching this i found this indicates the firmware needs updating. How could it loose the firmware update?

I updated the firmware on the Trig again and this kinda fixed it. However some other weird stuff is happening. When on the ground our tower with an ADSB receiver can see me, but in the air it cant. Flightaware shows me on the ground but not my flight track. Mode S seems to be ok. I have tried changing the flight detect and squat settings to no avail. Other ground stations receivers are seeing my MLAT or Mode S signal. Its almost like the ADSB disengages on takeoff or the squat switch EFIS flight detect is not working

Any ideas are greatly appreciated.
Many Thanks

Dan
G-MUSO

OK you have some valuable hints in your report.

The most valuable one is that your tower cannot see you when you have a bit of distance. This means either your transponders transmitter is blown or there is an issue with your antenna or cable/connectors.
Your Trig transponder is quite powerful with 250W of actual RF TX power - if that power cannot be absorbed by a matched antenna it is bad news for the transponder - that is a lot of energy and it can damage your transponder. In your case it appears to have corrupted the processors internal flash memory - but the previous version was still intact so it uses that as backup.

Please before you do any more with your transponder connect it to a transponder ground based test set (not a ramp tester) with a direct cable connection and verify that the transponder is producing rated power - this is given in dbm - you need around 54dbm (also take cable loss into account, usually the test equipment compensates for that - but you have to tell it). 54dbm = 250W.

If you don't get that power your transponder will need a new output transistor. These things are really expensive (REALLY EXPENSIVE) !

HI Rainer

Thanks for the quick responce. A couple of more bits of info to pass on.

ATC can still see my mode s while in the air from many miles away, and the antenna is a proper transponder one.
Its just a mystery that the adsb signal works fine on the ground then dissapears on takoff.

Thanks
Dan
G-MUSO

You should NOT have the extended squitter transmitting on the ground. The TT22 does not do ADS-B ground mode (which uses slightly different ADSB transmissions).
It would appear your squat switch is working the wrong way around.
Check your setup in the EFIS - normally you would use the automatic flight detect as trigger but you can also select an external input in which case you must also state the polarity.