What is the primary purpose of a screen grid in a vacuum tube?
To reduce grid-to-plate capacitance✓Bonne réponse
To increase efficiency
To increase the control grid resistance
To decrease plate resistance
Explication
The screen grid sits between the signal-controlling electrode and the plate and is bypassed to ground for RF, acting as an electrostatic shield that greatly reduces the grid-to-plate capacitance responsible for unwanted feedback. Improved efficiency is at best a side effect, not the purpose.