141. A magnetron is virtually a
A. high power amplifier
B. low power amplifier
C. high power oscillator
D. low power oscillator

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142. The TWT is sometimes preferred to the magnetron as a radar transmitter output tube because it is
A. less noisy
B. more broad band
C. capable of a longer duty cycle
D. a more efficient cycle

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143. Reflex klystron are available at operating frequencies as high as
A. 10,000 MHz
B. 30,000 MHz
C. 50,000 MHz
D. 70,000 MI-Iz

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144. Faraday effect occurs mostly in
A. HF frequency transmission
B. Simple radio transmission
C. Trans-ionospheric propagation
D. None of the above

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145.  Microwave link repeaters are typically 50 km apart
A. because of earth's curvature
B. because atmospheric attenuation
C. because of output tube power limitations
D. to ensure that the applied dc voltage is not excessive

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146. Waveguides are generally not used for frequencies
A. below 1 GHz
B. below 10 GHz
C. below 50 GHz
D. below 150 GHz

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147. Waveguides are considered superior to coaxial lines in the range
A. 30 MHz to 1 GHz
B. 1 GHz to 3 GHz
C. 3 GHz to 100 GHz
D. 100 GHzto 150 GHz

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