Muffin fans usually last longer running 24/7 vs turning on and off with PTT. I've had fans wired for PTT that would fail about every 2yrs and when the same fan was wired for continuous operation I never had to replace them again, or at least for about 5yrs until the equipment was retired. I have a 200w UHF Henry amp with a similar fan setup as the 300w lo band version and I was not happy with the stock fan setup. I put a 15 ohm 25w resistor across the thermal switch so all the fans run about half speed until the temp goes up then the resistor is bypassed and fans run at full speed. They cool pretty well with two on the heatsink fins and one pointed down at the circuit board and low pass filter.?
