One other piece of advice. To check trims and reverses I hook the boxes together and turn the master and the receiver on and set the throttles exactly the same on both boxes. Flip the buddy switch on and off and the control surfaces and throttles basically shouldn't move. Then, one at a time, simultaneously test each control surface and direction by giving "full" input in both directions. I,e. move give full right aileron on each box at the same time, then flip the buddy switch back and forth. Again, there should be no change in the plane when you flip the buddy switch. Repeat for all surfaces in all directions (full left aileron, full up and down elevator, etc).

Note also that reverse switches must be the same on both transmitters and, if the slave is a computer radio, it must be programmed to be completely neutral (no expo, no dual rates, etc.) and the reverses must be the same as the master. I used my 6XAS as a slave to a non computer radio and I just created an additional model in the memory that had the buddy box settings.

-Scott