190. Typical value of efficiency (r0 for a multicavity magnetron may be as high as
A.70%
B.40%
C.30%
D.90%

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191. Following data apply to a travelling-wave tube with helix as slow- wave structure Beam voltage (accelerating) = 100 V Beam current= 100 ILA Characteristic impedance of helix =300.0 Power output of travelling-wave tube is
A. 50 watts
B. 10 watts
C. 22 watts
D. none of these

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192. A directional coupler that has more than two holes is sometimes preferred overa two hole coupler because
A. it increases the system bandwith
B. it eliminates the spurious mode generation
C. it increases signal coupling
D. none of these

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193. In an H-plane tee,
A. all the three arms lie in the plane of electric field
B. all the three arms lie in the plane of magnetic field
C. all the three arms lie in a plane perpendicular to magnetic field
D. none of these

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194. The chief advantage of a TRAPATT diode over an IMPATT diode is its
A. higher efficiency
B. lower noise ability to operate at higher frequencies
C.both A and B
D. none of these

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195. In a microwave test bench, why is the microwave signal amplitude modulated at 1 kHz?
A. To increase the sensitivity of measurement
B. To transmit the signal to a far-off place
C. To study amplitude modulation
D. Because crystal detector fails at microwave frequencies

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