[AMRadio] Re: Triode connecting 803's for a Modulator


John Coleman ARS WA5BXO wa5bxo2005 at pctechref.com
Mon Apr 10 22:06:26 EDT 2006


	I was thinking that I had read an article published by RCA
explaining that the series grid resistor on 807/1625s, 20K as I recall,
was placed in circuit for linearity reasons.  It was having something to
do with a dip or a peak in transconductance mid way in the drive.  The
solution was simple but it did not come to the engineers right away.
Does anyone else remember the article or am I just imagining it, age you
know does funny things? Of course it would protect the grid as well but
I was thinking it was mainly for linearity.

John,
WA5BXO
     

-----Original Message-----
 On Behalf Of ne1s
Sent: Monday, April 10, 2006 12:04 PM
Subject: [AMRadio] Re: Triode connecting 803's for a Modulator

Elaborating on Don's comment, the reason this is done with the 
triode-connected 807 is that if the control & screen grids were simply
tied 
together, the control grids would be exceeding their maximum dissapation

before the screens could be driven hard enough to provide reasonable
output. 
We don't want to vaporize the control grids now, do we :>) I suspect
this 
would hold true for other tetrodes & pentodes in a triode connection. 







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