[Elecraft] KPA100 Fan Question

[Ron D'Eau Claire]

Doing some testing this weekend, I got to wondering as I listened to
that #&@$ fan whining away on the back of the KPA100. 

It CAN'T cool the rig. There's no other air opening in the K2 cabinet to
allow a 'flow' (except for a little gap around the old BNC antenna
connector). Indeed, I wonder if the whine isn't largely due to the fan
trying to move air through a nearly-closed box. A little back pressure
will make the sound level jump very fast. 

Exactly what does it do? 

I once heard it referred to as an air "stirrer" or "mixer" moving the
air in the enclosure around the distribute the heat more evenly. But
trying to move air in or out of a closed box seems a pretty inefficient
(and obviously noisy) way to do that.

I'm considering a larger, slower fan on the side of the rig. Mounted on
one of the side panels with holes drilled for air flow through the rig
using the hole presently occupied by the tiny little "whiner" in the
back. That would cool the rig more efficiently and the larger (3 in) fan
could turn more slowly and quietly. 

But, will that compound the frequency drift issues? I'm thinking of
putting it near the left front, where it would move outside air into the
K2 right near the PLL reference oscillator. Blowing on an oscillator can
be a very BAD thing to do for stable operation, especially one that
isn't well temperature compensated. The fan could go near the back
too... but just moving the air around more efficiently is not always a
good idea. 

I'm wondering if this ever came up and was pursued among the FT'ers and
others during the initial testing phases, etc.

Ron AC7AC
K2 # 1289