Hi Demetre, We are looking forward to your explanation as to how an unattended PMBO, very near to a local station (and which local station, that the far away client cannot even detect), and running a mode other than Pactor, will refuse to transmit over the local station's QSO if queried by the far away client.
It is easy to understand how this can happen on 20m where many use directional beam antennas. The local station does not even have to very "local" to the PMBO, but beaming in its direction for his QSO with a station in the direction of the PMBO, so that the client is off the side of the beam pattern. An operator at the PMBO could easily detect the beaming station, perhaps even over S9, but the client, being off the side of the beam, detects nothing and thinks the frequency is clear. This is critical to the problem of understanding how unattended stations can mix with attended stations on shared bands, and your explanation would be very much appreciated! Thanks in advance, Skip KH6TY