Hearing a very powerful (SIO 555) signal on 6903 kHz LSB, station calling CQ and saying "good evening" and "hello!" over and over again, either actually calling CQ or simply doing a radio check. Stations were on nearby frequency 6900 kHz USB only a few minutes before this (much stronger) station come on, and they are still busy chatting away on 6895 kHz LSB and 6900 kHz LSB. No ID heard. Now (0237 UTC) operator is whistling into microphone and suffering considerable QRM from QSO on 6900 kHz USB that has since returned.