[Amps] Grounded Screen 4CX1500B

[Shawn Tayler]

On Mon, 7 Nov 2005 02:35:36 -0800 R. Measures <r at somis.org> exclaimed:

> 
> On Nov 6, 2005, at 8:12 PM, Shawn Tayler wrote:
> 
> > Hi Guys,
> >
> > Playing with my 30S-1 has gotten me thinking about a project.  I've 
> > been
> > wanting an amp for 50Mhz for a while and I have 2 4CX1500B's lating 
> > around
> > as spares.  One would make a nice amp on 6M and I think I'd like to do 
> > the
> > grounded screen arrangement like the 30S-1.
> >
> > Could any of you comment on the pros and cons?
> 
> Less power gain in cathode driven config.
> 
> > The PS arrangement seems
> > unusual to me with the plate supply return on the groud ie. screen and 
> > the
> > cathode return appearing to go through the bias and screen supplies.  
> > I'm
> > sure I'm mis reading it.  IIRC the Continental 816 I maintained so 
> > years
> > back was of a similar arrangement, 4CX15000A.
> 
> Wasn't it grounded-screen, grid-driven, not grounded-screen 
> cathode-driven?
> 
> > But the plate screen and
> > grid supplies returned directly through the cathode with all kinds of
> > bypassing.
> 
> A seriously bypassed cathode means that it's grid driven.
> >
> > Comments?
> >
> > Shawn
> > N7LQ
> >
> > -- 
> > Mitchell's Law of Committees:
> > 	Any simple problem can be made insoluble if enough meetings are
> > held to discuss it.
> > _______________________________________________
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> >
> >
> 
> Richard L. Measures, AG6K, 805.386.3734.  www.somis.org
> 
> 

Hello Rich,

Interesting that you say this.  I was under that same impression from
conversations through the years.  I was happy to find that only the
screen is grounded, for stability.  The 30S-1 is a grid driven tetrode amp
otherwise.  I could never see how a 4CX1000A could function well in a
grounded grid mode.

Shawn
N7LQ



-- 
Mitchell's Law of Committees:
	Any simple problem can be made insoluble if enough meetings are
held to discuss it.