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Re: [Amps] grounding grids

To: "donroden@hiwaay.net" <donroden@hiwaay.net>, "amps@contesting.com" <amps@contesting.com>
Subject: Re: [Amps] grounding grids
From: "Fuqua, Bill L" <wlfuqu00@uky.edu>
Date: Mon, 3 Aug 2009 05:22:47 -0400
List-post: <amps@contesting.com">mailto:amps@contesting.com>
If I recall correctly there was an article in QST in the 60's of an amplifier 
using a pair of  4x150A tubes with both grids grounded but the output power was 
limited by the drive. About 2 issues later Bill Orr published one with a pair 
of 4x150A or 4CX250 tubes with the control grid connected to the cathode. He 
explained that if you connected the control grid to ground with the screen grid 
you would fry the control grid before you got full output. 
   I believe somewhere there were some articles on Super Cathode drive where 
the screen grid was connected  directly to ground but the control grid was on a 
tap near the cathode on the cathode choke. This allowed some drive to the 
control grid to increase the gain of the amplifier. 

73
Bill wa4lav

________________________________________
From: amps-bounces@contesting.com [amps-bounces@contesting.com] On Behalf Of 
donroden@hiwaay.net [donroden@hiwaay.net]
Sent: Sunday, August 02, 2009 10:47 PM
To: amps@contesting.com
Subject: Re: [Amps] grounding grids

But did anyone come up with the original article of using 4CX-250Bs in
"semi" grounded grid ?  I believe my amp used 100 ohm 2 watt on each
grid to ground with the screens direct to ground.

Don WA4NPL

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