[Amps] Fan for SB220

Sat Dec 18 11:37:59 PST 2010

Paint the inside and outside black.  The black inside will absorb the  heat 
more effectively and the black outside will radiate it more  effectively.

Bob
K8MLM

In a message dated 12/18/2010 1:45:29 P.M. Eastern Standard Time,  
rex at lint.mv.com writes:

So  what's the groups take on Measure's "paint it black"?  Debunked or  
still
a valid  argument?

http://www.somis.org/SB220ci.html

-Rex-

Rex Lint, Consultant
26 Brek Drive
Merrimack, NH  03054
PH:    603-860-7651    

-----Original Message-----
From:  amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf  Of Mike
Sent: Saturday, December 18, 2010 12:45 PM
To:  amps at contesting.com
Subject: Re: [Amps] Fan for SB220

If the  equipment has strong forced-air cooling, then heat-sink surface
finish  isn't very important.  If anodized with black oxide coating it  will
reduce thermal resistance up to 25% if convection cooling.

We  did these test in our development lab years ago to prove a point  to
marketing who wanted a silver look because it was  "Prettier".

Mike 

If the equipment has low airflow, then  radiation cooling becomes important,
and black anodized aluminum radiates  enormously better than bare unfinished
aluminum.

-----Original  Message-----
From: amps-bounces at contesting.com  [mailto:amps-bounces at contesting.com] On
Behalf Of Gary Smith
Sent:  Saturday, December 18, 2010 9:12 AM
To: Carl;  amps at contesting.com
Subject: Re: [Amps] Fan for SB220

This may seem  to be to at first but let me go on.
Years ago the same belief existed  regarding black vs. sliver on the
cylinders of cast iron Harley -Davison  motorcycles.  (Yes, I am that old I
have seen (and owned H-D's) with  cast iron cylinders.) One school of 
thought
was "paint`em black, it'll draw  the heat out rather than keep it in"  The
other group's belief was  "paint it silver, that will draw the heat out" and
so forth.  The  comeuppance was that H-D offered bother colors of paint in
touch up cans  when the cylinders got dinged to appease both groups
Pont here is make an  aluminum separator and paint it black?  Or just leave
it plain  finish.  Me thinks the difference in temp would not be worth  the
effort,  Its just a matter of belief.
But as a director of air  one way or the other, that's a different  subject.
Gary...wa6fgi

----- Original Message  ----- 
From: Carl 
To: donroden at hiwaay.net ;  amps at contesting.com 
Sent: Friday, December 17, 2010 6:33  PM
Subject: Re: [Amps] Fan for SB220

I dont see  how that shield helps anything Don, especially black. Have you 
done  any temperature tests on the tubes and shield? A shroud partially or  
fully encloses the fan as in automotive use.

Carl
KM1H

----- Original Message ----- 
From: <donroden at hiwaay.net>
To:  <amps at contesting.com>
Sent: Friday, December 17, 2010 10:36  AM
Subject: Re: [Amps] Fan for SB220

>
> Carl,
>
> I'm supprised no one  has mentioned adding a black aluminum shield
> between two 3-500s  to help prevent the two tubes from radiating heat (
> and rf )  into each other.  I've done this on my SB220, but didn't do
> any IMD measurements. It seems to improve the air flow too.
>
> Don R  W4DNR
>
> Quoting  Carl <km1h at jeremy.mv.com>:
>
>> 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
>>>
>>>
>>>  _______________________________________________
>>> Amps  mailing list
>>> Amps at contesting.com
>>>  http://lists.contesting.com/mailman/listinfo/amps
>>
>> _______________________________________________
>>  Amps mailing list
>> Amps at contesting.com
>>  http://lists.contesting.com/mailman/listinfo/amps
>>
>
>
>  _______________________________________________
> Amps mailing  list
> Amps at contesting.com
>  http://lists.contesting.com/mailman/listinfo/amps 

_______________________________________________
Amps mailing  list
Amps at contesting.com
http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps  mailing  list
Amps at contesting.com
http://lists.contesting.com/mailman/listinfo/amps

_______________________________________________
Amps  mailing  list
Amps at contesting.com
http://lists.contesting.com/mailman/listinfo/amps

_______________________________________________
Amps  mailing  list
Amps at contesting.com
http://lists.contesting.com/mailman/listinfo/amps