Screen voltage sets the maximum current at zero G1 voltage. Many data sheets show plate curves at G1 = 0, at several G2 voltages. If G2 voltage is higher than needed, the screen draws (wastes) more current, risks overheating G2, and enables more spectacular self-immolation and arcing.
There are two main reasons for running plate voltages at or near screen voltages:
1) to save the cost of a G2 supply - a resistor and cap, or a regulator, or a separate supply, whatever.
2) Ultralinear operation with a simple output transformer (no tertiary winding).
Both are economic, not performance issues.
There are two main reasons for running plate voltages at or near screen voltages:
1) to save the cost of a G2 supply - a resistor and cap, or a regulator, or a separate supply, whatever.
2) Ultralinear operation with a simple output transformer (no tertiary winding).
Both are economic, not performance issues.