WHAT’S THE FUNCTION OF FOCUS ADJUSTMENT AND ELECTROSTATIC FOCUSING IN MONOCHROME TV
The domestic television receiver is required to receive signal over a wide bandwidth and is based on the superheterodyne principle.
The television receiver is more complicated than a broadcast radio receiver because the former is required to reproduce a video signal, synchronized scanning waveform for the CRT and sound signal
THE BLOCK DIAGRAM OF A TYPICAL MONOCHROME RECEIVER.
1) FOCUS ADJUSTMENT: The focus adjustment is the electron beam. The electron beam must be focused to small ports/spot light on the screen usually focus is sharp on the center area of a tube.
FUNCTION: Older picture used in magnetic focusing with a focused signal on the neck of the tube behind the deflection yoke.
2) ELECTROSTATIC FOCUSING: Is omitted from a cathode tends to diverge because they repel each other. However the electron can be forced to converge to a point by an electric or to a magnetic field. So the voltage focused in the beam to a spot is called a crossed point beyond the control grid.