As I'm not a very technical person I just used a couple of resistors in parallel to slow the fan down in my 4225. I can't remember the values this early in the morning but it seems to be working just fine. The supply does run a little warmer but not hot and the fan is no longer heard.
Bill NZ0T Nick-WA5BDU wrote: > > This could almost be "on topic", as the desire to control the fan in my > MFJ-4225MV P/S is associated with my acquisition of a K3. There was > recently a discussion of switching power supplies for the K3 on the > list. I thought the MFJ unit was quiet while others found it to be > noisy. After the noisy fans in my FT-1000 and in my old PC left the > shack, the MFJ P/S did become the loudest box in the vicinity. > > I had a sense that the P/S didn't really need that continuous fan > activity, especially during low duty cycle operation or just listening. > So I put a temperature sensor on a heat sink and use it to turn the fan > on and off via a comparator circuit and MOSFET switch. I think it's > going to work out pretty well. Of course, the simple circuit could be > used on any P/S that runs the fan all the time but doesn't really need to. > > Schematic and lots of rambling chatter about the little project are here > -- > > http://pages.suddenlink.net/wa5bdu/fan_control_page.html > > 73-- Nick, WA5BDU > in Arkansas > #1195 > > > _______________________________________________ > 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 > > -- View this message in context: http://n2.nabble.com/OT%3A-fan-control-in-MFJ-4225MV-switching-P-S-tp667345p668219.html Sent from the Elecraft mailing list archive at Nabble.com. _______________________________________________ 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
