ADS-B barometric altitude encoding problem

[MacCool]

Just an update, as I've had a few queries via PM from pilots that were having the same or similar problem.

Regarding most of avionics, I am generally a total noob. I've been flying airplanes (certified) a long time but until I bought this RV-9A two years ago, my sole approach to maintenance and avionics was to take the plane to my A&P and/or avionics guy. The world of Experimental forces a re-thinking of that because I can't find anyone within 200 miles that knows ANYTHING about Advanced Flight Systems avionics in particular and glass EA-B in general. If I want to keep this plane flying and navigating, I have to rely on info from forums like this, or phone calls to AFS. AFS is very generous with accommodating those conversations, but each conversation is like trying to get a sip of water from a fire hose. It often assumes knowledge that I just don't have yet. I don't even really know how to frame the questions.

Anyway.... long story short, based on Jonathon's post above and sheer intuition and guesswork on my part, I changed the AHARS and Air Module settings in the 5400 (transmit) and in the 3500s (receive), and now things are working normally (0.0% BAlt failure) according to the PAPR that I ran today from a flight I did on Saturday.