I have a SPMA9575 Altimeter just installed on my Hex, but there is little information as to how it calibrates itself? If I set the Hex in the yard and power it up, it starts off lo, but creeps up to ~10-12' (the yard is 1505' AMSL). So, I assume it's attempting to zero itself at the current AMSL? Nevertheless as I watch it, even on the ground it will wander up as high as 25'. What can I expect the true verticle accuracy of these to be?
Also, is there a way to calibrate the TM1000 voltage monitor that's .2V off? My Hex doesn't glide on a low battery, it drops