> Conventional amps should be tuned at 100%, as Rich says. However, this doesn't
> necessarily apply if the amp has circuitry that allows correct tuning and
> loading to be achieved at lower power levels. Some do - not all. The auto tune
> amps tend to. If you have detectors on the input electrode and the plate so
the
> ratio of the RF volts on these two electrodes can be monitored, you can set
the
> loading correctly at low power. There was a 3-1000Z GG amp in the 1970 ARRL
> Handbook which did this. In a grounded cathode amp, if you monitor the
relative
> phase of anode and grid volts and maintain the TUNE control for them to be 180
> degrees out of phase, you can tune the tank without a plate current dip. It's
a
> bit more difficult in GG because of fedthrough power.
The Henry 4-K Ultra has this feature. A zero-center meter on the front panel.
(((73)))
Phil, K5PC
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