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
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