[Amps] Fan for SB220

[Carl]

Tests have shown that the turbulance from the high speed Harbach does little 
for the cooling unless a shroud is added. The one saving grace is a WW 
resistor can be added to reduce the speed a bit and reduce the noise; 
150-250 Ohms 20W seems to do well. Dentron and Amp Supply used a resistor in 
many of their amps.

Carl
KM1H


----- Original Message ----- 
From: "David G4FTC" <g4ftc at hotmail.com>
To: <amps at contesting.com>
Sent: Friday, December 17, 2010 1:47 AM
Subject: Re: [Amps] Fan for SB220


>
>
>> A local ham buddy just got back into the hobby after an 8 year hiatus and 
>> got a hold of 2 SB220's. He noticed they run hot and he asked the 
>> following question...so I figured there are folks out here who might know 
>> the answer
>>
>> "....see how guys like the Harbach fan kit for the SB220? Mine is running 
>> hot and LOUD. I oiled the
>> bearings and cleaned it off of dust, but it's still got to go"
>>
>> Anyone done this mod?
>>
>> I recommended a small muffin on top to help extract the hot air for now. 
>> I did it on my old 30L1 and it sure cooled it down.
>>
>> Thanks
>
>
>
> I'm using one of the Harbach fans on a SB220 - they move a lot more air 
> than the original Heathkit fans.
>
> Higher air-flow = higher noise
>
> But I can't say I've noticed that it runs hot.
>
> Regards
>
> David G4FTC
>
>
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