Hi Joe,
Not exactly the answer to your question but possibly useful. I received a fan replacement from the factory because my fan started making noises in speeds 1 and 2 after about 6 months. It sort of sounded like an overhead single engine airplane. Surprisingly that particular noise dissappeared when I manually advanced the speed to 3 or higher. The replacement I received was the identical model and it solved the problem.
73,
Mike K2MK
Joe Word-2 wrote
Has anyone replaced the fan in the KPA500 with a quieter one? If so, could
I get the model number? You can contact me off-list if you like, my email
is correct on QRZ.
Thanks,
Joe N9VX