Truckracer if you are looking to build something, I once had a c-band feedhorn with a polarotor1 on it (no feedback-just voltage only, reversed the voltage to switch H to V etc) When the receiver I had quit moving it, a very early model I forget which, I went to radioshack and bought a toggle-switch, and put a 9volt battery inside the metal box I mounted it on. Hooked up wires to it all from the feedhorn, and just pushed left or right on the switch to change polarity lol. Crude but it worked until I got a new feedhorn and better receiver.