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[AMPS] Re: The 3-500Z, having been officially beaten to death...

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Subject: [AMPS] Re: The 3-500Z, having been officially beaten to death...
From: Ian White, G3SEK" < (Ian White, G3SEK)
Date: Sat, 29 Sep 2001 09:12:23 +0100
Tom Rauch wrote:
>> AL-80B uses side-flow air cooling which appears substantial in volume
>> but does not use pressurized cooling, chimney, etc.  I can't complain
>> about its service, it's remarkable, but I remember reading lots of
>> material many years ago about how critical it was to keep the filament
>> pins below a certain temperature so as not to exceed the base seal
>> ratings, blah, blah...whatever.  I thought that was one of the primary
>> reasons for the pressurized cooling (blower, moving air from base to
>> envelope, up and out) systems used by Henry, Drake, et al in their
>> 3-500Z models.
>When the AL80A and later models were designed, seal and 
>envelope temperatures were measured at full rated power. In all 
>cases, all seals are well below ratings.
>That is contrary to some 3-500 amps, and even the original AL80 
>(the design was scrapped). The cooling system in the original AL80 
>had to be reworked with additional ventilation holes in strategic 
>positions and the fan changed to a TA450S from the original fan 
>that had a resistor in series with it.
>The original AL80, like most Amp Supply amplifiers, ran the seals 
>far over temperature in the interest of being "quiet" even when NO 
>RF drive was applied.

How do these developments relate to the Heath SB-1000? Are any
modifications required to the cooling?

73 from Ian G3SEK          Editor, 'The VHF/UHF DX Book'
                          'In Practice' columnist for RadCom (RSGB)

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