Garmin 650xi GPS source

I have a G3X touch and a 650xi. Both have about 100 flight hours and both have worked flawlessly since a few bugs were corrected. Today flying a practice RNAV approach with auto pilot (507) coupled and when established on the final approach course, the auto pilot would allow the RV to wander and then the 650xi indicated NO GPS source.

I later changed the G3X to internal nav source and the G3X displayed the course correctly.

I have reset the antenna connectors and removed and reset the 650. Any other suggestions?

Repeat the approach just like you did the first time, but now monitor the GPS satellite page on the 650. Make sure you transmit on the 650 as part or this data run.

What other radio do you have? Where is the 650 GPS antenna mounted?

Carl

Both the G3X and the 650 antennae are mounted just under the cowling at the firewall. My RV has been flying since 2016 and both antennae have been mounted in this area initially with a 430W and two non touch. All has worked well.

I had an identical problem with a GTN-650. It is associated with RFI when you transmit on the 650 - the RFI is created by other avionics reacting to the 650. This causes the GTN-650 to loose satellite reception. Garmin documents this issue someplace.

Monitor the satellite page on the 650 to see if you have the same issue. The fix is to move the 650 GPS antenna further away from the 650 - and hopefully whatever the other avionic component is contributing to the problem.

What are you using for Comm #2?

Carl

Com 2 is an SL30 with an archer antenna in the wing tip

Thanks for the info. I will give all that a try Monday. Out of town this weekend.

GDU 46X unit GPS signal

Couldn't find the satellite strength page for my GDU 460. The GTN is easy to find this. I see my position even in my hangar on the PFD but at times get this message in the air. I have the correct antenna installed and wanted to see the satellite strengths to troubleshoot. Surely has to be there. Help....

dmattmul said:

Couldn't find the satellite strength page for my GDU 460. The GTN is easy to find this. I see my position even in my hangar on the PFD but at times get this message in the air. I have the correct antenna installed and wanted to see the satellite strengths to troubleshoot. Surely has to be there. Help....

Click to expand...

[MENU]{outer right knob}[select INFO page]

Just an update. After checking to make sure antenna was securely connected and reseating the unit in its tray, I had good reception when flying today. I am not sure either was an issue but glad it is working normal. I will make the satellite reception a part of my runup if heading out of the local area and especially if I have filed IFR.

Flyyak said:

Just an update. After checking to make sure antenna was securely connected and reseating the unit in its tray, I had good reception when flying today. I am not sure either was an issue but glad it is working normal. I will make the satellite reception a part of my runup if heading out of the local area and especially if I have filed IFR.

Click to expand...

If you do determine that transmitting from either com radio blanks any of your GPS signals, you will need to install one of these in the COM antenna feed. https://www.southwestantennas.com/filter-modules-diplexers-triplexers/l-band-filters/1080-154

Edit: excerpt from the XI installation manual.

“The GPS antenna should be mounted:
a. No closer than 2 feet from any VHF COM antenna or any other antenna that may emit interference. Complete an aircraft EMC check to ensure there is no GPS degradation. Refer to Section 5. If an EMC check reveals unacceptable interference, a GPS notch filter (Garmin P/N 330-00067-00) can be inserted in line with the offending VHF COM or the (re-radiating) ELT transmitter, or a different GPS antenna location can be selected. The GPS/WAAS antenna is less susceptible to harmonic interference if a 1.57542 GHz notch filter is installed on the COM transceiver antenna output.”

Thanks

bjdecker said:

[MENU]{outer right knob}[select INFO page]

Click to expand...

Brian, appreciate the help.

AHRS GPS Source

dmattmul said:

Couldn't find the satellite strength page for my GDU 460. The GTN is easy to find this. I see my position even in my hangar on the PFD but at times get this message in the air. I have the correct antenna installed and wanted to see the satellite strengths to troubleshoot. Surely has to be there. Help....

Click to expand...

What antenna do you have connected to the G3X Touch display?

Thanks,

Justin

G3X Touch FDL

Flyyak said:

I have a G3X touch and a 650xi. Both have about 100 flight hours and both have worked flawlessly since a few bugs were corrected. Today flying a practice RNAV approach with auto pilot (507) coupled and when established on the final approach course, the auto pilot would allow the RV to wander and then the 650xi indicated NO GPS source.

I later changed the G3X to internal nav source and the G3X displayed the course correctly.

I have reset the antenna connectors and removed and reset the 650. Any other suggestions?

Click to expand...

Do you by chance have a G3X Touch Flight data log from this flight you can send us ([email protected])? The GDU records a lot of different parameters from the flight and it may provide some clues as to what happened.

Thanks,

Justin