GDL90/GNS480 error?

[PhateX1337]

I've started getting this error on the GNS480 screen and a MSG alert on my GMX200 that shows this error. From what I can tell, it's completely infrequent/can't determine that anything's causing it other than maybe push to talk occasionally while I'm on the ground? Always seems to trigger when I push to talk, but not every time I push to talk. In the air it's pretty stable, only done it a couple of times - far less than on the ground.

Any thoughts? As simple as the GDL90 is going bad?

[Andy95W]

I noticed the frequency you have tuned- 120.90- and your standby, 121.75.  It is not uncommon for frequencies in the 121 range to interfere with your GPS reception, which I’m betting is causing your 480 to lose its position and  then that affects the GDL- since that’s the WAAS GPS feed for your ADSB.

Whichever transmitter is doing it may have to go in for work, or if it’s an older King KX model, you may have to install a COM antenna on the belly.

I bet the problem doesn’t happen if you’re transmitting on a frequency above 128.xx.

Keep us posted!

[PhateX1337]

Interesting, thanks. In addition to the pictured, I have a SL30. So your thought is one of those is causing interference in the ~121 range? I'm scheduled to install a GTN750 in place of the GMX200 and 480 in a couple weeks, so I want to make sure I get this part fixed too.

Thanks Andy!