One important point here is that with most radio's, the systems must be exact in order to use the computer functions (expo, D/R, End Points, Centering, and so on). That is, my system, for instance, is an Airtronics RD6000. I must have a similar radio, another RD6000 connected via the trainer cord in order to set the plane up for such things as D/R and so on. I would assume the same thing for other manufacturers systems, but I might be wrong. I can, however, use my RD6000 and the Airtronics basic buddy box. The only thing that happens is that the controls and trim work but not the computer functions of the RD6000.