> -----Original Message----- > > The air stream from the internal fan flows into the K2 under the KPA100 > heatsink and emerges from the front. That way it keeps much of the heat > out of the box. > That is why I recommend pulling the air upward from the heat sink - so it will help pull the air from inside the KPA100 as well - in the same direction as the internal fan moves the air. The ideal in my opinion is to have just enough external fan that the amount of time the internal fan runs is substantially reduced, but will still run with extended transmit periods (like RTTY or PSK31 operation). Doing things that way, it is mandatory that I not buck the normal air flow of the internal fan.
For purposes of cooling a heat sink, it is just as effective to pull the hot air away from it then to concentrate an air stream to blow onto it. As an added benefit, it also pulls away any dust that may be in the air rather than causing it to load up on the heat sink and reduce the cooling effectiveness. A 12 volt auxiliary fan can be slowed down to about half speed by the addition of a series resistor, and will likely stay in place with no fasteners unless you have the KPA100 in a vibration prone environment. A slower fan will be much more quiet than one running at high speed and will be quite effective. The heat sink may get quite warm to the touch but it should not be so hot that you cannot hold your hand on it. 73, Don W3FPR _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
