Do you really need a stabilized screen grid supply? If the g2 voltage
follows relatively slowly the envelope of a SSB signal, you should get a
only a slow gain variation in the tube??? You have then to use a large
condenser across the g2 voltage. If I remember right ( and I may be wrong
)looking into the NAG gg two meter 4CX350 linear the g2 voltage adjusted
itself to the average drive level and you could use anything from 3-10 watts
of drive with good linearity.I used the famous IC 202 as a very clean driver
- the linear supplied the 13.5 VDC
This is in direct contradiction to my own experience with the NAG. For a
start, when miss tuned and driven with 10W the screen voltage goes up,
increasing the gain. A simple screen regulator greatly improves the
amplifier and mine is now working reasonably well on 70 MHz at our 160Watt
limit. The lower output helps survival with the hopelessly inadequate
cooling fan.
Even in its original state, when correctly tuned the NAG was very much
cleaner than many solid state "linears", much better than the driver in many
cases, but it could be so much better.
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