[Elecraft] OT: fan control in MFJ-4225MV switching P/S

[John Payne]

Just a thought here...

There are many fans for computers which have a thermal control for the 
fan speed built in.  I suspect it's just a temperature-variable resistor 
in series with the power lead.  This could be a viable alternative for 
cooling of almost any thing which needs it, and these things are cheap.  
Look for phrases like "thermally controlled", "temperature controlled" 
etc.  With just a bit of searching, one can also find fans listed as 
"silent".  Many sellers of these fans list the sound level in DB, which 
makes comparison easy, they almost always list RPM and CFM specs as 
well.  Also a variety of sizes from 40mm to 120mm and more.  Try Cooler 
Guys <http://www.coolerguys.com/>,
 NewEgg <http://www.newegg.com/>,
  Xoxide <http://www.xoxide.com/casefans.html?> just to name a few.

Hope this may help.

73, John W4CWZ

Alan Bloom wrote:
> Yes, I expect a voltage regulator would work better than a resistor to
> drop the voltage.  Since the fan motor draws more current at startup
> than when it is running, a contant-voltage source should give
> more-reliable startup at a lower voltage.
>
> But you probably still want to use a thermostat or some other method to
> switch the fan to full voltage if things get too hot.
>
> Al N1AL
>
>
> On Tue, 2008-08-05 at 05:06, Kenneth A. Christiansen wrote:
>   
>> I used a 5 volt regulator on my MFJ 4225 to slow down the fan. This allows
>> the fan to start reliably at any voltage. I have run mine and my K2-100 this
>> way for at least 5 years with no problem on SSB, CW and DIGITAL.
>>
>> 73
>> Ken W0CZ
>>
>> Bill NZ0T Wrote
>> <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
>>
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