127. A folded-di gole antenna used with television receivers has a terminal impedance of___ohms at its resonance frequency.
A.75
B.300
C.50
D.150

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128.  In any transmitting antenna system, efficiency primarily depends upon
A. ohmic losses of various conductors
B. radiation resistance
C. ground conductivity
D. atmospheric conditions

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129. The demodulation of the sound signals in a TV receiver is accomplished by
A. linear detector
B. product detector
C. discriminator
D. envelope detector

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130. The service area of a TV transmitter for satisfactory reception is determined by ? zone.
A. line-of-sight
B. diffi-action
C. tropospheric
D. regional tropospheric

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131. The service range of a TV transmitter is determined by the height
A. of the transmitting aerial
B. of the transmitting and that 'receiving antenna
C. of the transmitting and that receiving antenna and power transmitter
D. and gain of the transitting and receiving antenna and power of the transmitter

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132. The function of the serrations in the composition video waveform is to
A. equalize the charge in the integrator before the start of vertical retrace
B. help veritcal synchronization
C. hele horizontal synchronization
D. simplify the generation of the vertical sync pulse

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133. The gain of a simple half-wave dipole over an isotropic radiator is of the order of ?dB.
A.2
B.6
C.7
D.8

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