I have a feeling that to get the higher gain in gg with a tetrode will require
there to be volts on the screen grid. If it's directly grounded, you need a big
drive signal to get the peak plate current and that could over dissipate the
grid.
73
Peter G3RZP
========================================
Message Received: May 05 2013, 07:05 AM
From: "Markku Oksanen" <ww1c@outlook.com>
To: "jtml@losalamos.com" <jtml@losalamos.com>, "amps@contesting.com"
<amps@contesting.com>
Cc:
Subject: [Amps] FW: 4CX5000A in common grid circuit
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...
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|