Mode C help.
 

Hello. I am A little puzzled. For the past month of flying I had few times when the tower said they weren't receiving my Mode C, it has happened on take off, it has happen inbound for landing. has been intermittent. My set up is Dynon D10A (has a built in encoder), GTX 327, Uvionix EchoUAT, IFD440. in the past I have cycled the transponder and tower was able to see my mode C, another times it didn't happen, another time I cycled the dynon and transponder it worked. today I took off in the morning it was fine, later in the day when I came back tower said i had no mode C, (he sees me, Ident is good, just no ALT) I tried cycling the transponder, Nothing. Tried the D10a, nothing. tried both at the same time Nothing. landed and still no mode C. i will try flying tomorrow to see if it is back alive.
Can anyone guide me how to troubleshoot this one? I was thinking of finding a 327 and swap out with mine to test it for few days. OR?
I am In KMOD for another week or so.

thanks

How is your D10A altitude data wired to your transponder? Is it serial (RS-232) or parallel (Gray code)? If it is gray code via a converter, there's twice the opportunity for a loose connection.

Whether its gray code or serial, I'd recommend you visually look at the wiring and each connector between your D10A and your GTX-327 to make sure they are secure.

I am connected via serial, D10A encoder transmit pin13 to gtx Rs-232 in- pin2

It has worked Flawless till about a month ago. Today I ran a ADSB performance report and i got to red boxes 1st is under "missing elements" - Flight ID and Baro Alt.
Both are red its the very 1st section of the report. Having a hard time figuring out if it is the D10A or the 327. I don't think the ADSB has any fault on this is also just not receiving the info i guess.

I will check the connections tomorrow.

If I’m not mistaking, the uAvionics Echo gets its altitude information from the transponder so either your transponder itself is intermittent or the Dynon encoder is intermittent, probably due to a poor electrical connection somewhere. If the transponder interrogation reply indicator in on when this is happening, my bet is on problem with it not receiving the encoder information consistently.


Skylor

Rico, definitely check that 327. I just worked through a friends issue with a new GDL 82 install with the same unit. It was a failed transponder and had to be factory repaired. It also has a software update you might need, so check the version number. I don't recall precisely the version needed, but it did relate to an altitude issue with the ADSB pickup.

So, check your transponder and sw version. Serial altitude is recommended as precision is higher than gray code.

Does the xpdr display altitude data when the mode c is inop?
I assume it is losing that data from the dynon/wiring as I've never seen one display altitude but not transmit the data.

Echo app
 

What does echo app show while on ground? If you can get a interrogation blip on transponder, check the EchoUAT app on your phone and see if you show squawk 1200, pressure and gps altitudes. Should see all three. EchoUAT gets its data for altitude and squawk after transponder receives and transmits it out by sniffing micro voltage on plane wiring of this transmitted data. If not seeing data, drop sensitivity on EchoUAT lower....lower means increased sensitivity. Good luck.

Skylor, thanks for the reply.

I will inspect the plug integrity and connection.

Hello Bill.
I am hopping that this issue is the transponder. I am trying to locate one around Modesto that I can input my same settings and do couple of test flights. That would be the easiest way to rule out the transponder. I will check the SW version. I am connected via serial.

Is there any way to check if the dynon is sending the ALT info? specially when they report not getting my Mode C?