232. The shadow mask in colour TV picture tube is used to
A. reduced X-ray emission
B. increases screen brightness
C. ensure that each beam hits own target
D. none of the above
233. In a TV receiver, the colour killer
A. prevents colour, over loading
B. ensure that no colour is transmitted to monochrome receivers
C. cuts off the chroma stages during monochrome reception
D. makes sure that the colour burst is not mistaken for sync pulses by cutting of reception during the back porch
234. Selectivity is provided and interference is rejected by the
A. transmission line
B. local oscillator
C. RF amplifier
D. Emitter by pass capacitor
235. The contrast control functions to very
A. the gain of the IF amplifier
B. the bias on the picture tube grid
C. screen brightness
D. the gain of the video amplifier
236. Peaking coils function by
A. resonating at certain frequencies with circuit capacitances
B. filtering the ripple in the power supply
C. trapping adjacent channel interference
D. stabilizing transistor operation
237. The DC component of a video signal corresponds to __ in the image.
A. back ground illumination
B. Maximum illumination
C. contrast
D. detail
238. The de-emphasis network consists of a/an
A. differentiating circuit with a time constant of 75 11 sec.
B. differentiating circuit with a time constant of 75 sec
C. integrating circuit with a timeconstant of 75 l.t sec
D. Integrating circuit with a time constant of 75 sec.
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