Flew 182 from Az.-Kan. on Sunday for 6 hrs enroute with stop in
Tex for gas. After level off at alt. took Spot tracker, that I've been
using for almost 10 years, out of bag and put on glareshield and
turned on. Few minutes later noticed the autopilot was not tracking Nav
on the GTN750, which are both new install. Reset Nav and continued. Happened
again in about 10 mins. and checked GPS signals...all dropped off but all eventually
came back after about 1 min. This continued all the way to Kansas,
every 10mins. Called Garmin after landing and come to find out
they consider the Spot Tracker a jammer. Apparently the location
of where I placed it on the glareshield, was in a direct line up with
the antennae, which is above my head on the top of fuselage and also
too close to the 750. They recommended to not use it in the airplane
or try some other location. With all this new technology and the
bluetooth, WiFi and other interfaces talking to each other it gets rather
busy in a small confined space. I'll check it when I pick up the airplane
in a couple of months.

Warranty troubleshooting on the SPOT FAQ page says interference is a possibility and to keep it 12 inches away from other devices. I think same goes for any uplink device.

I have seen SPOT Gen3 make the GTN series loose GPS signal on multiple airplanes.

G3X it doesn't usually completely loose it's location but will significantly degrade the GPS signal.

Huh....well, THAT might explain a few things!

They’re talking about it over on Beechtalk as well.
Seems like a legit problem although I haven’t experienced it.