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.
>>
I would use the power output control that is on most all the transceivers
these days to not drive the AB1 amp into grid current.
Terry - W6TG
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