[AMPS] Class AB1 Grounded Grid?

Rich Measures measures@vc.net
Sat, 17 Jul 1999 08:09:59 -0700




>
>Hi Bill,
>
>>     For other reasons I will be modifying my GG 4-1000A amplifier
>> so that I can apply bias to the grids. Have any of  you operated
>> a 4-1000A class AB1 as a grounded grid amplifier? Is it 
>> more linear than the usual zero bias triode connected configuration?
>> TNX ES
>
>Years and years ago, in my wilder days when I ran "big" power, I 
>used a pair of AB1 4-1000A's cathode driven.
>
>I regulated the screen with 6146's, and regulated the bias with a 
>solid state regulator.

€  Tom:  More pos. screen volts means more ZSAC - which must be countered 
with more neg. grid bias.    Unless there is a tangible benefit, 'tis an 
exercise in futility.  
>
>It was much cleaner than conventional zero bias grounded grid, 
>although it drove with almost the same power. 

€   In order to realize max. gain from a tetrode, the input signal is 
applied to the grid, the cathode is RF-grounded - and the screen is RF 
grounded.  Other wise, a tetrode (or pentode)  won't deliver the goods.  

> .  As I recall it was 
>about 10 dB or so better for IMD performance than AB2 zero 
>screen voltage GG.
>
€  A friend of mine in San Diego found that in cathode driven service 
there was virtually no difference in performance or drive requirement 
when various DC biases were applied to the RF grounded screen and RF 
grounded grid.  
>
-  Cheers, Tom


Rich...

R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures  


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