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06-03-2023, 11:02 AM
Hi Guys
Champ81: Both of your drawings are correct.
Regarding bias: Tubes are CATHODE-CENTRIC so their reference is the cathode. Grid voltage has to be negative with respect to the cathode for there to be control over cathode current. Plate voltage has to be positive for there to be current through the tube. Screen voltage (when applicable) has to be positive with respect to the cathode for there to be current through the tube.
VOLTAGE IS RELATIVE. There is no "negative" or "positive" until you decide on a reference point, as explained in RSG Ready, Set, Go!
In both cathode-biasing and fixed-biasing, varying the voltage between the cathode and grid is what varies the tube current.
The cathode can be at what you decide is "ground", or any voltage above or below. For the tube the latter makes no difference.
Champ81: Both of your drawings are correct.
Regarding bias: Tubes are CATHODE-CENTRIC so their reference is the cathode. Grid voltage has to be negative with respect to the cathode for there to be control over cathode current. Plate voltage has to be positive for there to be current through the tube. Screen voltage (when applicable) has to be positive with respect to the cathode for there to be current through the tube.
VOLTAGE IS RELATIVE. There is no "negative" or "positive" until you decide on a reference point, as explained in RSG Ready, Set, Go!
In both cathode-biasing and fixed-biasing, varying the voltage between the cathode and grid is what varies the tube current.
The cathode can be at what you decide is "ground", or any voltage above or below. For the tube the latter makes no difference.
