[AMPS] Tetrode Amp articles needed

Rich Measures measures@vc.net
Thu, 5 Jun 97 14:40:51 -0700

>In a message dated 97-06-05 10:19:50 EDT from W8JI, you write:
><< In the practical world, ALC is actually MORE necessary in a class AB1 
> PA. The slightest grid current will send the PA into distortion 
> quickly with most AB1 grid driven designs.
> The correct way to install ALC in an AB1 PA is to sample PEAK RF grid 
> voltage, and activate the ALC as peak positive voltage approaches the 
> quantity of negative bias voltage. 
> In other words, if the bias voltage is -50v, ALC should be activated 
> whenever positive RF voltage peaks approach or reach 50 volts. Any 
> ALC sampling grid current will be "too late" to do any good, so the 
> system has to be a peak voltage detector.
>  >>
Would it not be simpler to adjust the bias voltage a bit higher than 
minus 50v, so that the grid can't draw distortion-producing grid current, 
and then increase the screen V until the ZSAC increases to normal (like 
Eimac recommends).  Why waste power output unless there is a danger of 
exceeding the max. anode current rating?  

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

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