RE: Futaba recievers
Dual conversion has nothing to do with shift. It is simply how the receiver detects and handles the rf input. Dual conversion first converts the incomming signal to a lower frequency (12.7 MHZ I think), amplifies it and then converts it again to 455 KHZ where it is once more amplified and decoded. A single conversion receiver just converts the incomming signal to 455 KHZ immediately.