Thanks for all your help with the orientation of the zener and the
related tests to determine the true cathode direction. The zener was
indeed mis-labeled which caused me all kinds of turmoil.
One additional question about the value of a zener and it effect on
output power: I recently built an amplifier with a pair of 8877's
currently making 2500W output (Bird 43 w/2500w slug) with a 100W of
drive. It features a small footprint custom built power supply with a
2 amp Peter Dahl Hipersil making about 4200VDC. There's a 12VDC zener
installed providing about 300ma of idle plate current with a no signal
key down excitation for the pair of tubes. Ameritron's AL1500 operator's
manual indicates that their single 8877 should idle at 250ma.
Extrapolating for a pair of 8877's, idle should be about 500ma.
Here's the question, If I were to lower the zener value to 10V (thereby
raising the idle current closer to 500ma from the present 300ma), how
would that alter the RF output if all other parameters remained
unchanged? I wouldn't have bothered asking if I had a 10v zener and I
really didn't want to clutter up the amp with a long string of diodes.
Any info would be appreciated. I do have 5.1v zeners but I didn't know
for certain if the pair in series would simply add a variable that would
cloud the question. 73's Ron W2CQM/3
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