I was listening to AO-7 in Mode B as it rose at 2153Z. At 2158Z, AO-7 suddenly switched from Mode B to Mode A. At the time of the switch, there were two stations using excessive power (badly FMing) on the bird. Not sure if that was a coincidence or not. Called CQ on Mode A in both CW and SSB with no response. 73 Glenn AA5PK