[ARC5] Smart People: Triode Connecting Pentodes

[Fuqua, Bill L]

  There was a lengthily discussion on AMPS years ago about supercathode drive amplifiers.
And sometime during that I found some information on the screen to plate amplification factor.
But, I can't recall where.  So, I could be wrong about that. 
   But low mu is the reason for its low gain performance in grounded grid applications. 
The mu for a 304TL is 12. Which has similar performance in grounded grid applications per
the Radio Handbook. But their example is class C if I recall. 200Watts in for around 900 Watts out.
Have to look it up. I remember toying around with the idea of a grounded grid 304TL once. Actually at 
one time I did try it just as an experiment in my 4-1000A amplifier chassis. Only had around 100 Watts drive
but it did work. 
  As I said the figure could be incorrect and is not one typically specified and I can't recall now where I got it. 
Another thing. In measuring the G1 to G2 transconductance in a 4CX250 the plate would have to 
be at ground potential. During normal tetrode operation the screen grid current is nearly zero and sometimes
negative which really confuses matters. 
   
73
Bill wa4lav

________________________________________
From: Kenneth G. Gordon [kgordon2006 at frontier.com]
Sent: Thursday, November 14, 2013 5:47 PM
To: Fuqua, Bill L; ARC-5 List
Subject: Re: [ARC5] Smart People: Triode Connecting Pentodes

On 14 Nov 2013 at 22:34, Fuqua, Bill L wrote:

>   The screen to plate mu is around 6 for the 4CX250b.
>
> 73
> Bill wa4lav

Bill:

Where do you find those sorts of specs? I have needed some like those for
many years....such as the grid to screen transconductance of a 6AG7 for
instance.

Ken W7EKB