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Re: [Amps] Fan for SB220

To: K8MLM@aol.com, rex@lint.mv.com, noddy1211@sbcglobal.net, amps@contesting.com
Subject: Re: [Amps] Fan for SB220
From: K8MLM@aol.com
Date: Sat, 18 Dec 2010 14:43:06 EST
List-post: <amps@contesting.com">mailto:amps@contesting.com>
I meant to add.  The big glass tubes cool the anodes by  radiation.  Base 
seals and anode seals are convection cooled.  Black  both absorbs and 
radiates heat more efficiently than any other color.
 
Bob
K8MLM
 
 
In a message dated 12/18/2010 2:39:04 P.M. Eastern Standard Time,  
K8MLM@aol.com writes:

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@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@contesting.com  [mailto:amps-bounces@contesting.com] On
Behalf  Of Mike
Sent:  Saturday, December 18, 2010 12:45 PM
To:   amps@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@contesting.com  [mailto:amps-bounces@contesting.com]  On
Behalf Of Gary Smith
Sent:  Saturday, December 18, 2010 9:12  AM
To: Carl;  amps@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@hiwaay.net ;  amps@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@hiwaay.net>
To:   <amps@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@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@hotmail.com>
>> To:   <amps@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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>>
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>
>
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