[AMRadio] Re - response to input to screen grid amplifier

Bob Bruhns bbruhns at erols.com
Wed May 24 11:13:19 EDT 2006

Bill, assuming you want to use it as a linear, you should keep it as-is and work out how it is producing control-grid current like
that.  I have to think that the screens are tied to the control grids somewhere.

  Bacon, WA3WDR

----- Original Message ----- 
From: "Bill Fondren" <bill.fondren at sbcglobal.net>
To: <amradio at mailman.qth.net>
Sent: Tuesday, May 23, 2006 5:04 PM
Subject: [AMRadio] Re - response to input to screen grid amplifier

> Thanks for the quick response to my questions concerning this amp.   John, I was ready for some salty remarks (hihi)  and I did
clean my glasses and take a second or third look at the thing.  I thought I had missed something since going to USAF Radio School in
the early 50's. Guess that tells u why I mess with vacumn tube rigs.  Anyway thought I better get some expert opinions before
starting to cut and chop to get it to a more conventional type.  The construction of the amp is above average for a homebrew rig.  A
couple of other things     There is a RFC choke  coming off the G1 connections going to the 10K resistor then to the grid meter
(0-30ma shunted with a 50 ohm 10 watt resistor)  It does read about half scale peaking normal as u tune the grid circuit. Also a .01
bypass cap at the meter.  The input coil is grounded in the middle through a RFC choke making a double coil, tuned by a split stator
cap. One of the tuned circuits goes directly to the screen grids and the
>  other feeds the neutralizing voltage back to the input from the plate. No bias circuits of any kind. The few times I used it I
got good reports using a Elmac AF-67 exciter.   Will probably change it to a more conventional type.   Thanks again     Bill  K5PML
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