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[Amps] FW: 4CX5000A in common grid circuit

To: "jtml@losalamos.com" <jtml@losalamos.com>, "amps@contesting.com" <amps@contesting.com>
Subject: [Amps] FW: 4CX5000A in common grid circuit
From: Markku Oksanen <ww1c@outlook.com>
Date: Sun, 5 May 2013 06:05:43 +0000
List-post: <amps@contesting.com">mailto:amps@contesting.com>




All

I found this 
http://www.cpii.com/docs/related/22/C&F4Web.pdfand it looks like chapter 4 of 
Pappenfus' if I understand it correctly.
Against current "wisdom" this states (page 104)  that a properly designed 
tetrode in GG will give a gain of 20 to 50 while triodes tend to remain below, 
at the level of 7 to 20, 20 seems to be a sign of a good design these days with 
modern high muu tubes.  
Can anybody help with this???  Is this correct?  I have never before heard that 
tetrodes in GG can give such high gain. Are there specific requirements for the 
tube??
I still didn't find direct gain formula but managed to calculate some estimates 
based on voltage gain and impedance levels.  What the GG muu value to use with 
a tetrode is, I don't quite know.
Looks like it makes good sense to try a GG design first with the some 
forethought in case grid drive becomes a necessary change later. Gain of over 
20 is plenty good enough.
Thanks for the hint / help!


Markku WW1C

> Date: Thu, 2 May 2013 16:28:16 -0600
> From: jtml@losalamos.com
> To: amps@contesting.com
> Subject: [Amps] 4CX5000A in common grid  circuit
> 
> 4CX5000A is in the Collins design in the 1964 Ed of Pappenfus' SSB 
> Principles. It will give you a reference point. If you can find the NAB 
> handbook from the 1986 era, I wrote the section in FM transmitters, comparing 
> a 4Cx3500A in to and gg circuits, class c though, at 100 MHz. Its a similar 
> but better tetrode. If you put voltage on the screen you can get fairly high 
> gain, like 12 db I think. Memory may be fading here.
> 
> Sent from on the road...
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