[AMPS] Zener Diodes

[Yellowstone Photo - Barri]

I've built a few amplifiers over the years, but only one using Zener 
diode bias.  This is the most recent one: 8877 for six meters.

I built it "cookbook" style, following a couple of different plans 
published in CQ.  I used a 14 volt Zener.  The amp appears to work well, 
and according to reports sounds good.

My only problem, if it's a problem, is that the efficiency appears to be 
low: 55%, if I can believe the meters.

Would a different value of Zener have any effect on efficiency?  

The grid current runs lower than published figures at full output.  The 
resting plate current is about 100ma.

I can pull 1.2 amps at 4000 volts with 90 watts drive.  Again, if I can 
believe the meters.

I'm using, for the first time, a floating B-.  

Any help with this would be appreciated.

Barrie, W7ALW

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