WHAT’S THE FUNCTION OF FOCUS ADJUSTMENT AND ELECTROSTATIC FOCUSING IN TELECOMMUNICATION II

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.

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