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Re: [Amps] 572B grid

Subject: Re: [Amps] 572B grid
From: Jan Erik Holm <sm2ekm@telia.com>
Date: Sun, 23 Jul 2006 20:45:44 +0200
List-post: <mailto:amps@contesting.com>
Just got corrected by a friend.
30L-1 is 4 tubes and SB-200 just 2,
I forgot.
Oh well, I must be getting old.
170W isn´t as bad as I tought then.

/SM2EKM
--------

Jan Erik Holm wrote:

> Yes but 170W into 2x572B´s that´s heavy. I bet IMD
> was quite poor.
> I´m not familiar with the 30L-1 but for a SB-200 around
> 75W is enough.
> However I remember back in the early 70´ties the school
> I went to had a SB-200 and a TR-4 I used most every
> lunch break, the darn SB-200 got so hot that the lid had
> to be open all the time plus it would pop the fuse/breaker
> ever so often, I bet the darn thing ran a KW output but
> also splattering quite a bit. Nobody did complain and
> I didn´t know better.
> However those 572B´s where quite long lived, as far as
> I know during the 2 years I was there we never replaced
> any tubes.
> 
> 73 Jim SM2EKM
> ------------------------------------------------------------
> 
> Vic K2VCO wrote:
> 
>>Vic K2VCO wrote:
>>
>>
>>>kenw2dtc wrote:
>>>
>>>
>>>>"I've never understood the raison d'etre for the introduction of the 572B. 
>>>>I gather it was meant as a cheap SSB tube"
>>>>
>>>>Perhaps this tech bulletin from 1964 will explain:
>>>>
>>>>http://w2dtc.com/1964-waters-tech-bulletin.jpg
>>>
>>>This is very interesting, because it contradicts what I've believed: 
>>>that the 572B offers no additional power output over the 811A unless you 
>>>raise the plate voltage.  But this bulletin says that simply plugging 
>>>them into a 30L1 and increasing drive will increase power output by 33%. 
>>> What's the truth here?
>>
>>
>>I take it back.  That's 33% *without* increasing drive.  It's 75% if you 
>>increase drive!
> 


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