[Elecraft] KPA100 Temp/Fan

[Andrew Moore]

> When operating CW the
> fan turns on high during every transmission and the heat sink gets hot to
> the touch.  I'm a ragchewer so my transmissions do run to several minutes
> and, regardless of power setting, the fan will kick on high after several
> minutes of transmitting.
...
> Does anyone have an idea what may be wrong?

I think this is normal.  I had the same experience and asked about it
and in the end realized that's how it behaves.  It's the primary
reason I went back to the QRP cover.  Fan is just too noisy and comes
on too often.  It also failed to turn off by itself after going back
into RX mode -- it took a deliberate keying event to, apparently,
force the firmware to re-evaluate the temp and disable the fan (which
of course causes a transmission and confuses the op on the other
end!).  Where or not that part was normal I don't know, but it's the
way mine behaved (on two different KPA100's).  I don't know which
firmware it had so don't know if that's been addressed in a newer
version.

If I remember correctly, the amp is most efficient at about 75 watts,
so operating there might help cut down the heat and delay the fan
turn-on.

You might also look into other cooling methods -- larger, slower fan;
remote fan with custom duct work; active cooling; etc.

--Andrew, NV1B