How compatible is the 8981A with the SA 8566B? Can I plug the 8981A's demodulator into the IF of the 8566B and get I and Q quadrature display? Where do I plug the two units into one another? What do I use for the phase reference signal input to the 8981A? So together they would work as a vector modulation receiver? What would be the maximum bandwidth for the setup. Would I better look into the SDR's that give I/Q off the IF of the SA -- the higher the better frequency such as the 325 MHz IF from the 70K series SA for example. Thanks folks.