RE: Spektrum system getting hit when turning on another 2.4 GHZ transmitter
Interesting problem. Take the following as a logical thought process; I'm not an expert on radio systems. Since both radios were bound to the same receiver, could there be the possibility that the receiver could still be wanting to react to the old programming in the 12X? Since the receiver did not react at all to your friend's DX7, proves that the system is still working as designed(blocking the signal of a radio that it was not bound to).
Could the answer be in the "steps" that you took from the time you decided to change from the 12X to the DX18? Did you plug or unplug any satellite receivers? Any of the "steps" that you took may be the culprit on why part or of your system is still reacting to the 12X. Are you sure that all satellite receivers are going into bind mode when going into the binding process?
Rafael