Utterly Mad

Getting two frequencies into your HEM unit would be the reward to some arduous quest, maybe even the main line, so don't worry about the OPness.

There would be some repercussions for losing contact while the HEM units are active and transmitting, probably something along the lines of the HEM units being knocked offline for a short period of time. If the conditions are right, the thing the two users were manipulating could explode too.