A common complaint about the FT-847 is that the fan noise is irritating
(and it is). I have been able to quiet the whine using the following method:
Cut a 3" x 3" piece of soft packing foam that is about 2" thick. Be sure to use
the "open cell" type of foam. You can tell that it is open cell type construction
by holding it up to your mouth and blowing air through it. Wedge the piece of
foam between the four coax connectors so that it covers the intake area for the
fan. The whine will then disappear. The foam has little effect on the cooling
of the radio. I think it works because the foam causes turbulence in the air flow,
disrupting the formation of the sound of the whine, which is probably generated
by the tips of the fan blades. It may even slow the fan a bit, which stops
thenoise. However it works, it works. I can't even see it when it is in
place. It should also have an added bonus in that it will filter dust from the air
before it enters the radio.
Hope this works for you.