GRT altimiter questions

I am currently working out the little issues you run across when starting to fly a new plane.
I have a GRT Sport EX, EIS and GTX 327 in the RV3.

I have calibrated the altimeter to the field baro setting per GRTs instructions.
However, the FL shown in the txp window is about 300' low and I get a message after boot up that the gps alt difference is 200'

I have a call in to GPS, but as usual, would like instant gratification as to what I will have to do to get everything calibrated.

Any suggestions?
Thanks in advance.

GTX327 will show the same altitude as the GRT Sport altimeter if you crank the barometer setting to 29.92. You should always expect to see a difference in the transponder reported altitude and the altimeter reading any time the actual barometer setting is not 29.92.

As for the GPS alt difference, that's a totally different challenge which may indicate the altimeter calibration is incorrect. Just for grins, set your Sport altimeter to field elevation and record the barometer setting. Now go to another airplane like your buddy's 172 and crank its altimeter to the field elevation and record its barometer setting. Now compare the baro settings between your airplane and your buddy's. If there's a significant difference then your Sport altimeter may need calibration.

Also, make sure the GRT Sport EX has had a chance to warm up as the altimeter pressure sensor does drift a little bit as it comes up to temperature. OK, a semantic correction... I have seen this happen on my HX so assume it will do likewise on the Sport EX. Hoping it will warm up enough that I can install the Sport EX in our aircraft shortly.

Well, I already got a call from Jeff at GRT. Always get great response from them.

You are correct about the 29.92 for the barometer setting.

As for the GPS difference, I was in the hangar and my GPS signal probably only got one or two satellites. Per Jeff, once I get out and get more satellites, the altitude should correct itself and be much closer to my field settings.

Thanks for your input.