While I wait for my economic stimulus check so that I can get some OPTs I have been fooling with possible load lines. Starting with Gary Kaufman's 5K, 150V, 50mA, -20V grid I played with several different load lines. I could increase the predicted power from 0.9W up to about 1.5W but in most cases predicted third harmonic increased as well, some times by a lot.
The best thing I came up with was his same load line but biased at -30V (190V 42mA) which predicts over 1.5W with similar distortion distribution.
This gets me to the question. If I use this more aggressive bias the full power distortion may be slightly higher but for a power triode the distortion is less as you decrease output from maximum. So in theory the distortion at 0.9W (the max at the old bias point) might actually be less.
Anyone know how to best estimate the distortion at the lower output?
mike
The best thing I came up with was his same load line but biased at -30V (190V 42mA) which predicts over 1.5W with similar distortion distribution.
This gets me to the question. If I use this more aggressive bias the full power distortion may be slightly higher but for a power triode the distortion is less as you decrease output from maximum. So in theory the distortion at 0.9W (the max at the old bias point) might actually be less.
Anyone know how to best estimate the distortion at the lower output?
mike