One thing you do have to watch is that servos have three leads - positive, negative and modulated signel input. Some drive the signal inputwith a positive modulation shift and some drive the signal input with a negative shift. The two don't play nice together and the receiver has to be designed to work one or the other. Futaba and HiTec, for instance, are compatable negative servos. JR and Airtronics both use positive shift; though JR makes servos in both modulations. Not sure about Spektrum but Ibelieve Iheard they are negative shift.