Hi I am in Tasmania, Australia and not running any products down, just telling it like it is, and just need a fix for this problem. I really prefer the Airnav product aspecially the software side ,I think ANRB is far superior. I also have both boxes and find the performance to be similar - except the null. You can rule out anything to do with antennas, coax, computers, location, interference it just comes down to the box itself
Mike