Climbed to 9.5K and established level cruise between HIO and Independence, OR. Engaged Navaid Devices AP-1 for functional status to follow HEADING and COURSE functions. Using EFIS Heading signal, it tracked on heading from HIO to Indep. Engaged VOR course tracking TO the UBG VOR from different directions and did a better job getting to the VOR than I could manually. It also correctly followed GPS tracking from the AvMap EKP IV. However, GPS tracking from the GRT EFIS is a problem as it makes unstable Left & Right cross-track hunting. Since other signals work to the AP, the issue appears to be signal gain related to the GRT EFIS itself. So far, I'm very happy with AP functional results.
