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
_______________________________________________
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
|