Dave, In heat removal, the name of the game is air circulation, which is different than just 'blowing air' - there must be an escape path for the heated air. In the KPA100 that path is from the back to the front of the unit, the air escapes through the heatsink fins just behind the top of the front panel. If you have something (even a piece of paper) on top of the KPA100, it will block this air flow and reduce the cooling capacity - which in turn will cause the fan to come on earlier than expected. If you have the KAT100 stacked on top of the KPA100 I suggest changing things to place the KAT100 below the K2/100.
An easy way to add an auxiliary fan to the KPA100 is to place a muffin fan on top of the heat sink - pulling air away from the heat sink. Even a slow moving fan will help, a DC fan salvaged from a computer will do nicely and you can slow it down with a series resistor. 73, Don W3FPR > -----Original Message----- > > I was playing around with the KAT100 a couple of nights ago and > was leaving the K2/100 on tune for periods of 15 - 20 seconds at > a time (20W) at intervals through several bands. After a few > minutes, the whizzer fired up its engine, so if your average Tx > power is 20W then you have maybe 5 mins before the little > hovercraft starts up. > > I note it blows air INTO the KPA, but there doesn't appear to be > much by way of provision for the warmed air to get out, so I > guess oscillators are going to move around quite a bit when the > warm air circulates around and around. Maybe a nice, quiet > ex-computer muffin fan sitting on top of the heatsink might be a > better way of cooling the PA? > > 73 Dave L G3TJP > -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.432 / Virus Database: 268.15.9/571 - Release Date: 12/5/2006 11:50 AM _______________________________________________ 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
