I have been following this discussion with some interest. This morning I set the idling fan speed to 1, and after sitting at the same desk with it for a couple hours, I am really no longer conscious of the noise (I have other things happening).
The non-operating temp has settled in at 28ºC. And now, after 5 consecutive 15 second JS8 transmissions, and running at 275 watts, the temp has risen to 59ºC and no change in fan speed. After the 6th consecutive transmission, the temp rises to 62ºF and the fan goes to #2. Temps after each 15 second interval are 37, 44, 50, 55, 59 and 62ºC respectively. With the fan at "Norm," the temp settles in at 31ºC. Running the same test, temps after each 15 second interval are 39, 44, 49, 53 56 and 59ºC - so it never goes to #2. The bottom line seems to be that there is nothing gained by setting the minimum fan speed at #1. In fact, you might make the case that running the fan unnecessarily will just add more dust to the interior over time and thus reduce the long-term cooling efficiency. Of course, the ambient temp in your environment will skew these results. 73, Lyn, WØLEN -----Original Message----- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Andy Durbin Sent: Tuesday, October 01, 2019 11:52 AM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] KPA500 - Advantage of min fan speed? Thanks to everyone who contributed their experience of operating with min fan speed set above 0. I have some ideas for a test series and I'll share anything I learn from it. Here is a teaser for those interested in KPA500 thermal management. Did you know that, for a KPA500 that has not transmitted for a long time, the Z bracket is hotter than the heat sink and the heat sink is hotter than the finals. For that condition the heat flow is from the Z bracket, into the heat sink, and then it heats the finals. The heat flow reversed during TX as the finals heat up. 73, Andy, k3wyc ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to l...@lnainc.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
