D100 Autopilot Disconnects Nav Mode when transmit

[morhall]

My setup:
Dynon D100
pitch and roll servos
Dynon firmware 5.6 (just upgraded from 5.4.3)
Garmin 430w GPS/Comm


When the autopilot is engaged on Nav mode, transmitting for a few seconds can cause the Nav Mode to disconnect. It seems to stay connected for Altitude Hold. I did not notice if it failed back to Heading Mode or not. I need to test that scenario. I think it did, at least when I went to reengage the autopilot, the mode was now Heading and had to be reselected to NAV.

I read the sticky thread regarding GPS dropping out on 5.4. Upgraded to 5.6 in the hopes that this was the root of the issue. I've only got one flight where I was using the AP and had this happen since the 5.6 upgrade. But it caught me by surprise when checking in with ATC and noticed the AP was no longer on Nav Mode.

The audio announcement is very faint (need to try and adjust that) but I believe I got an audio annunciation.

My suspicion is that during transmit, the GPS sentences are somehow garbled and the D100 falls back rather than follow erroneous data.

Any suggestions on troubleshooting this issue?

Thanks,

Morgan

 

[dynonsupport]

The only way to definitively troubleshoot this would be to get a capture of the GPS sentences coming from the 430W providing AP guidance to the EFIS-D100. You also might try updating the firmware of the 430 to the latest firmware.

I suggest routing the coaxial cable from the COM radio section of the 430 away from anything involving the AP. For example, if it passes behind the EFIS-D100, route it the other direction. It's relatively easy to add coaxial cable extensions to reroute this cable.

My setup:
Dynon D100
pitch and roll servos
Dynon firmware 5.6 (just upgraded from 5.4.3)
Garmin 430w GPS/Comm


When the autopilot is engaged on Nav mode, transmitting for a few seconds can cause the Nav Mode to disconnect. It seems to stay connected for Altitude Hold.  I did not notice if it failed back to Heading Mode or not.  I need to test that scenario. I think it did, at least when I went to reengage the autopilot, the mode was now Heading and had to be reselected to NAV.

I read the sticky thread regarding GPS dropping out on 5.4. Upgraded to 5.6 in the hopes that this was the root of the issue.  I've only got one flight where I was using the AP and had this happen since the 5.6 upgrade.  But it caught me by surprise when checking in with ATC and noticed the AP was no longer on Nav Mode.

The audio announcement is very faint (need to try and adjust that) but I believe I got an audio annunciation.

My suspicion is that during transmit, the GPS sentences are somehow garbled and the D100 falls back rather than follow erroneous data.

Any suggestions on troubleshooting this issue? 

Thanks,

Morgan

 

[morhall]

Thanks for the suggestion. I will have to see if I have the cables and ports to log NMEA data coming from the Garmin.

Assuming I'm getting NMEA data, will the Autopilot need to be engaged? I'm assuming that the 430 doesn't know what equipment I have it connected to and just sends NMEA data out and assumes any connected devices will do the right thing with that data.

I'll see if I can get more separation between the Coax and the D100. I actually added an extension earlier this year to connect a different antenna to the 430 so I may have a little more wiggle room already.

Thanks,

Morgan

 

[Dynon]

The NMEA goes out in the blind, so your capture won't be dependent on what you're doing with the D100 or AP.