Icebound wrote:
Robert Briggs wrote:

Let's see, you know that the guy is transmitting on one frequency,
but what about his second box?

If he's using it to monitor another frequency then, with a spot of
educated trial-and-error, you may be able to get through to him.

Does the side-tone of the transmitter not take over his intercom?

Possibly; but it's not as fundamental a problem as trying to use one
radio both ways simultaneously.