[AMPS] Re: Response of Rich

[measures]

>Rich:
>
>I raised the question of increasing the screen voltage on a grounded grid
>tetrode - from zero to something less than the "normal" voltage.  Your
>response was that "DAF circuits produce feculance".
>
Is that the only thing you saw on my reply?

>Your latest response is:
>
>"Did I not also point out that the power out with your stated screen
>potential was comparable to the power from the driver?."
>
>Your answer does not make sense.  Let us assume we have a normal grounded
>grid tetrode.  

> Now, we break the screen lead to ground and insert a 1 volt
>regulated positive voltage upon the screen.  Will the power output drop to
>that of the driver?  What about 2 volts?   

Gain does not change.  In the example you previously gave I had the 
impression that we talking about grid-driven config   Cathode-driven is a 
whole nuther ballgame.  

> As the screen voltage is
>increased, resting plate current will increase and at some point grid bias
>will have to be applied as the plate changes color from red to white.

Or, one could wake up and stop increasing screen potential.  
>
>In a grounded grid tetrode, the control grid current will be greater than
>the screen current.  By raising the screen voltage above ground, control
>grid current will decrease.
>
>What sort of interesting curve do you have that shows that power output
>drops to the input power as soon as the screen voltage is raised above
>ground - yet will reappear as soon as the screen voltage is raised to the
>rated screen voltage.  That would be an inverted square, wouldn't it?
>
>The 4-400 is rated to have 100 ma of control grid current when used in
>grounded grid configuration. 

Whose spec is this?

> Are you saying that as soon as I lift the
>screen above ground  that any grid current will cause splatter?
>
Hardly. Significant grid current in  grid-driven config.  causes 
significant distortion. 

later, Colin

-  Rich..., 805.386.3734, www.vcnet.com/measures.  
end


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