ADAHRS cross check error

[Scott Campbell]

So I'm having problems getting an ADAHRS cross check error and the magnetic compass "drifting". I believe my problems are related to how close I have other instruments located to the two ADAHRS units. At first I thought it was my Whelen light power supply box that was causing the interference, when I turn the strobe lights on while on the ground I can see the needle of a hand held compass move significantly. I flew one flight with out the lights on and thought the problem was solved but, I have flown subsequent flights with the lights off and the error comes back. Now I think it is either my ADS-B in which is mounted about 18" away from the ADAHRS or the transponder antenna which is about 3 feet away. I wouldn't think it is the ADS-B in because I assume, maybe incorrectly, that it is receive only. My question is how far away should the ADS-B in be located (box and antenna) and how far away should the transponder antenna be from the ADAHRS? This is in an RV8 and the two ADAHRS units are mounted on top of the stringers behind the aft baggage compartment. Any help is appreciated!

 

[Rhino]

Three feet should be more than enough antennas separation, provided you used good cables. I'd suspect box location.