[Elecraft] Fan controller for MFJ-4125 power supply

[n1al at cds1.net]

I had 13 replies from people wanting to build my fan controller for the
MFJ power supply, but unfortunately I only had enough spare parts for four
units.

Fortunately, the parts are easy to get (Digi-Key part numbers are listed
on the web page listed in my original message, copied below).  The PC
boards are available for $4.00 plus S&H from FAR Circuits, or will be as
seen as I send the film artwork back to Fred KF9GX, owner of FAR Circuits.
 http://www.farcircuits.net/  Refer to the "BLOOM FAN CONTROL BOARD".

Thanks to everyone for their interest.

Al N1AL


> The MFJ-4125 "PowerLite" power supply is a great little unit for the price
> (around $100).  It puts out 13.7V at 25A in a small, light package that is
> perfect for portable operation with the K3 or K2.  Unlike some other
> switching supplies, it has very low electrical noise.
>
> Unfortunately the same can't be said for acoustic noise.  The loud fan is
> the one thing people complain about.  So I designed a fan controller that
> reduces the fan voltage for normal operation while running it at full
> speed when the internal heat sink warms up.  I've posted an article on my
> web page:
> http://www.cds1.net/~n1al/ham/fan_controller.htm
>
> I have enough parts left over to build 4 more units.  If anyone is
> interested I can supply a kit of parts for $5 postpaid/USA that includes
> the clamp and all electrical parts except for the TIP-29 power transistor.
>  (I'll throw in a TIP-31 from my junk box that that should work the same,
> or you can obtain the exact part yourself.)  I also have a couple PC
> boards left over that I'll include while they last.  Email me if you're
> interested:  n1al at cds1.net .
>
> Al N1AL
>