Do you know anyone that has had first hand experience in running 4CX5000
tubes in conventional grounded grid configuration? I have some that I would
like to try perhaps. They have 75Watt control grid dissipation and 250 Watt
screen grid dissipation.
73
Bill wa4lav
________________________________
From: Amps <amps-bounces@contesting.com> on behalf of Jim Thomson
<jim.thom@telus.net>
Sent: Tuesday, October 30, 2018 12:27 PM
To: amps@contesting.com
Subject: [Amps] Super Cathode Driven Tetrodes
Date: Sun, 28 Oct 2018 23:46:21 +0000
From: "Fuqua, William" <wlfuqu00@uky.edu>
To: Carl <km1h@jeremy.qozzy.com>, Jim Thomson <jim.thom@telus.net>,
"amps@contesting.com" <amps@contesting.com>
Subject: Re: [Amps] Super Cathode Driven Tetrodes
<Ok,
< Now that this discussion has gone on for some time, and everyone has had a
opportunity to read various articles, here is the question.
<Can anyone give me a reason why a cathode driven tetrode with the control grid
connected directly to
<the cathode be unstable. The screen grid is connected directly to ground. Low
mu grounded grid configuration.
<73
<Bill wa4lav
## Its rock stable, based on data from the 70s, from nearby hams who used
that config. But that was a 4CX-1000
in both cases. 160 w of drive for 1200 w pep out on ssb / cw..... = power
gain of just 7.5..... = 8.75 db.
The super cathode driven config was only used on tubes that had virtually no
control grid dissipation, like 4CX-1000, and 4CX-1500B etc.
Tubes like 4CX-5000, and bigger, can have both their control grid and screen
grid bonded to chassis.. and run like a high mu triode.... just like a 4-400,
or 4-1000.
Jim VE7RF
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