[Hallicrafters] HT-33A Fan Assembly Needed

[Al Parker]

hi Bob,
	OK.  I have an HB amp with pr of 4-400's, have a good sized muffin 
below the chassis to pressurize there & blow air up thru holes around 
the tubes (no chimneys).  Then a small muffin above them, exhausting 
air.  Seems to have been OK for yrs, but no long transmissions, no AM, 
etc.  It lives in the "upstairs shack", the Henry in teh "shop shack".
	The Henry 3K-A uses a pr of 3-500z's, with chimneys and pretty strong 
airflow up thru, from husky fan below.  Much better.
73,
Al

On 4/16/2010 4:31 PM, rbethman wrote:
> Al,
>
> Been about 8 years ago since I was looking at the insides of a '33.  SK,
> WC3K was going to let me have it with a spare PL-172, along with an
> SX-88, and an HT-32B.
>
> All had been restored to original.
>
> Can't always remember which big tube needs what!
>
> You "can" get away with the real "froggy" muffins even on 3-1000s and
> 4-1000s, although I would rather pressurized the chassis and use a
> blower and chimney.
>
> The 3-500Zs have been real happy with the AC high volume muffin.
>
> (Senior Moment?)
>
> I'll go back to sleep!
>
> Bob - N0DGN
>
> On 4/16/2010 4:05 PM, Al Parker wrote:
>> Hi Gary,
>> 	Yup, you've got it.  I think some of the guys haven't realized that
>> this tube is an external anode, finned, air cooled, tube similar in
>> configuration, but bigger, to  a 4CX350 series, etc.  It requires a
>> specific air flow to properly cool it, and that necessitates more
>> pressure than what's required to cool glass 3-500's, 4-400's, etc.
>> 	I had a "modified" HT-33 for several yrs, but sold it last yr due to
>> acquiring a Henry 3-KA which replaced it.  You can see at
>> <http://www.boatanchors.org/HT-33hb.htm>    I thought there might be a pic
>> of the bottom, showing the fan, but guess not.  I do have a complete,
>> nearly original, HT-33B that I can drag out&   get pix or info if you
>> need.  It's a future project, I do have one good tube for it.  There've
>> been threads on the Halli&   BA reflectors every so often abt those
>> tubes, and the fact that most glass ones are gassy by now.  It's said
>> that keeping filament voltage on them every month or 3 is helpful,it
>> might be, but it won't restore a real flat one (experience).
>> 73,
>> Al, W8UT
>> www.boatanchors.org
>> www.hammarlund.info
>
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