All of testers. How noisy are the cooling fans? Especially for those that were in the RTTY contest last weekend.
That is a relative question. When operating in a contest or using full duty cycle modes, the amp will require additional cooling of the transistors and this means moving more air across the heatsinks by spinning the fans at a faster rate than when operating lower duty cycle modes. To some people, the fan noise will not be objectional. Others may find it excessive.
I've found normal mode to be very quiet in the amp I've been able to observe. Contest or intermediate mode is about equivalent to the level generated by the 6500 when the fans kick in at higher temperature...noticeable, but not objectionable. "Broadcast" mode, on the other hand, sounds like a vacuum cleaner, but that's not something you're likely to need unless you're running something like a full-bore RTTY SO2R contest.