G'day, | The fact that an exhaust fan flow cools objects better than blowing air onto | a surface is a bit counter-intuitive because standing in the downstream side | of a fan feels cooler to the skin - but that is only because of evaporation. | Careful measurement will show that the cooling effectiveness for an object | like a heat sink is more effective by moving the heated air away from the | object. Getting the heat away is the objective, and blowing on it is less | effective than exhausting the heated air.
Never seen a suction cooled external anode HPA, from single 4CX250's to 10kW Klystrons. I've used a small PC fan blowing onto the right hand side of the heatsink, front to rear, inclined about 45 degrees. During 10-12 hour QRSS beacon runs at 40W o/p the little fan never came on and the heatsink was room temperature. A bladed fan is easy to stall if there is any restriction to throughput. Regards, Mike VP8NO _______________________________________________ Elecraft mailing list Post to: [email protected] 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
