Nin hao George,
Have your built the amplifier like this GG configation?there are two article
give the result,100W in and 600w out,but I doubt these result.
73! Hsu
----- Original Message -----
From: <gdaught6@stanford.edu>
To: "Hsu" <hsu4qro@gmail.com>
Sent: Sunday, July 12, 2009 12:42 AM
Subject: Re: [Amps] Grounded Grid(Screen) 4CX250B power gain
> Ni hao Hsu,
>
>> Anyone have experience in grounded grid a pair 4CX250Bs amplifier? could
>> you tell me how much power gain of this configation?
>> This weekend, I'm planing to do a tube conversion in my friend's Henry
>> tempo 2001(a pair 3CX400A7),I have give up GI-7B due to its
>> larger volume.The only choise is 4CX250B.The gride driven configation needs
>> screen and grid power supply,so I want to use G-G configation
>> (gird+cathode as cathode,screen as grid, due to the 4CX250B grid's few
>> power rating, it is low mu triode now).
>> But I don't know its exact power gain,anyone can tell me about this?Thanks
>> in advance!
>
> You are right that the screen grid and control grid can't be tied together,
> like you
> could with a 4-1000A or similar tube. And you are also right that using the
> screen as
> the grid in a grounded-grid amplifier results in a low mu. (It will be only
> about mu =
> 5 according to my old Eimac data sheet for the 4CX250B). So it will take a
> very
> large amount of driving power to get the output power you desire. It's much
> better to
> build a screen power supply for use of tubes like this.
>
> vy 73,
>
> George T Daughters, K6GT
> CU in the California QSO Party (CQP)
> October 3-4, 2009
>
>
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