The new version of AvMap software was developed for the TRIO autopilot but it suffered from the same problem as the dynon. In the data stream where the dynon was looking for magnetic variation there was a blank. We ran the beta software for AvMap that was written for the autopilot to test it on the dynon. It fixed the problem. Instead of a blank in the data stream there is now magnetic variation. The "direct" setting on NMEA will give the old data stream. The "Processed" setting gives new information (magnetic heading). It certainly fixed mine. I now have good winds data and the HSI presentation is accurate.
I also changed the antenna. I used a smb-bnc cable and a Garmin GA-56 antenna. That is the very common external mounted antenna. Got mine from the local avionics guy (free). They are removing them from a lot of airplanes now because when the Garmin's are upgraded to WAAS, a new antenna is required. A bunch of these are on ebay for that reason. I mounted mine under the engine cowling (behind the baffling using adel clamps attached to the rear cross frame of the engine mount in the "cool" section). The fiberglass cowling is transparent to gps signals. I get a much better signal there than I had when the puck antenna was on the instrument panel hood or other places in the cockpit. It is also nice not to have all of those wires running around the cockpit. I just have to plug in the AvMap and then attach two short wires (antenna and serial data) which are permanently under the panel.
I also changed the antenna. I used a smb-bnc cable and a Garmin GA-56 antenna. That is the very common external mounted antenna. Got mine from the local avionics guy (free). They are removing them from a lot of airplanes now because when the Garmin's are upgraded to WAAS, a new antenna is required. A bunch of these are on ebay for that reason. I mounted mine under the engine cowling (behind the baffling using adel clamps attached to the rear cross frame of the engine mount in the "cool" section). The fiberglass cowling is transparent to gps signals. I get a much better signal there than I had when the puck antenna was on the instrument panel hood or other places in the cockpit. It is also nice not to have all of those wires running around the cockpit. I just have to plug in the AvMap and then attach two short wires (antenna and serial data) which are permanently under the panel.