In Reply to: RE: So, mostly for MI amps. posted by DAK on September 26, 2016 at 18:22:14:
I've never used a single resistor, and I can't recall seeing that in commercial designs. However, many designers use no resistor whatsoever, probably believing (true or not) that screen stability isn't an issue. Regarding one resistor vs. two, maybe there's an advantage to a single resistor in a push-pull output stage. For optimum pentode operation, the screens must be held at a steady voltage, relative to the cathode. Installing a non-decoupled series resistor of any value at the screen degrades this characteristic. However, a single resistor connected to both screens should allow the push-pull voltages created by screen currents to mostly cancel. This probably results in operation closer to true pentode.
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Follow Ups
- AC Screen Current - Triode_Kingdom 10:14:04 09/27/16 (1)
- What Triode said-nT - Cleantimestream 10:36:21 09/27/16 (0)