[AMPS] Is screen potential important?

[measures]

>
>Rich says
>
>>Not until the screen bypass C becomes sufficiently charged
>
>But if this is 5 time constants,  it's still far faster than the rise time of
>the envelope.

My guess is that it takes more than this.  For an 8171 operating no lower 
than 3.5MHz, the screen/cathode capacitance is around 0.05uF.  For 
1.8MHz, around .iuF.  Also, the input signal is a voice.  Since voice 
duty-cycle average around 15%, how are you going to charge the screen 
bypass cap to the needed 1500v with a15% source.   
>
>>In order to achieve linear amplification, current gain must be constant 
>>at All signal levels.  
>
>What current gain? 

The ratio of the current delivered to the 50-ohm load divided by the 
sinewave current delivered to a resonant 50-ohm input.  

>As over at least part of the input cycle, there's no
>input current, current gain is inapplicable. 

This is true only when the grid circuit is not resonant. 
>.....
later, Peter

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


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