Bias Circuit and Standby check

[Shadrock2]

Well Dave... The Aiken sight started off using only a resistor then demonstrated why a zener might be better. Then they went back and showed how zener bias would not respond to line voltage fluctuations. They also implied that using just a resistor was like using cathode bias. I do not want cathode bias so I have some characteristics of both. I have also "heard" that zeners can add noise. I want to filter that out and isolate it from the bias output. That is my thinking anyway.

I have later realized that people have used zener diodes in place of cathode resistors to gain a little extra power.

[Dave H]

Well Dave... The Aiken sight started off using only a resistor then demonstrated why a zener might be better. Then they went back and showed how zener bias would not respond to line voltage fluctuations. They also implied that using just a resistor was like using cathode bias. I do not want cathode bias so I have some characteristics of both.

I see so it's 'mixed bias' now. With the resistor it will track the line voltage to some extent and also bias a little cooler when driven hard. I guess back biasing came from the time before we had silicon diodes to easily make a bias supply. You could do that.

[pdf64]

I thought that a key benefit of the back biasing for this project was to knock the VB+ down a bit?