[Amps] The maximum amount of 811As and 572Bs in parallel

[Hsu]

Richard,
    I see, too much tube  means  much drive.Myebe I can not use the cathode drive.
      I have seen a very old Chinese military 1600W HF  transmitter(final is FU-100F=4CX1000A)
 the pre-driver are 8*6P15's(simlar 12BY7,but 6.3V filament) in parallel in" transmisson line" mode.
 Very rare mode.
     73! Hsu

----- Original Message ----- 
From: "R L Measures" <r at somis.org>
To: "Hsu" <Jbenson at sohu.co>; "Hsu" <Jbenson at sohu.com>
Cc: <amps at contesting.com>
Sent: Sunday, July 23, 2006 9:57 PM
Subject: Re: [Amps] The maximum amount of 811As and 572Bs in parallel


> 
> On Jul 23, 2006, at 4:05 AM, Hsu wrote:
> 
>> Hi,
>>    I have seen some schematic diagram of amplifier, I found that  
>> the amount of 811As and 572Bs no more than four, Coud someone can  
>> tell me how much  maximum amount of the tubes in parallel?
> 
> Tektronix used to use c. 10 tubes in their O'scopes' deflection plate  
> amplifiers.  The story about paralleling more tubes having too much C  
> is a large pooper scooper of taurine feces because if the # of tubes  
> is doubled, twice as much C in needed to keep the operating Q in the  
> desired 10 - 15 range. If I had 300W of drive, I would not hesitate  
> to build an amplifier with 10, 572Bs or 811As.
> cheers, Hsu
> 
> 
>>   Thanks!
>>         73! Hsu
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> 
> R L MEASURES, AG6K. 805-386-3734
> r at somis.org
> 
> 
> 
>