[AMPS] 4-1000 Screen Voltage

[Rich Measures]

>I've heard that applying regulated 3-400 volts to the screen of a cathode
>driven 4-1000 in grounded grid will lower the drive requirements.  Any
>comments? 
>
-   This is yet another old wives' tale, Bob.  In order for screen 
amplification to take place, the signal must be applied between the grid 
and the screen - which is why the screen is bypassed or grounded.  Adding 
screen voltage to a g-g amplifier shifts the ZSAC, but does not change 
the drive requirements because no signal voltage exists between the 
screen and the grid in a g-g tetrode amplifier.    .  .  To reduce the 
drive requirements for a 4-1000A, drive the grid, apply at least 6kV 
anode and 1kV to the screen.  The grid needs to be fed through a 1 to 4 
bifilar step-up broadband transformer, and the grid needs to be 
terminated in 200-ohms.  
Rich...

R. L. Measures, 805-386-3734, AG6K   


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