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  • Question

  • Consider the following statements

    1. Bunching of electrons occurs in two cavity klystron amplifier.
    2. Bunching of electrons occurs in multi cavity klystron amplifier.
    3. Bunching of electrons occurs in reflex cavity klystron amplifier.
    Which of the above statements are correct?


  • Options
  • A. 1, 2, and only
  • B. 1, 2 and 3 only
  • C. 1 and 3 only
  • D. 2 and 3 only

  • Correct Answer
  • 1, 2 and 3 only 

    Explanation
    A Klystron is a vacuum tube used for generation/amplification of microwaves.

    An electron beam is produced by oxide coated indirectly heated cathode and is focussed and accelerated by focussing electrode.

    This beam is transmitted through a glass tube. The input cavity where the beam enters the glass tube is called buncher.

    As electrons move ahead they see an accelerating field for half cycle and retarding field for the other half cycle.

    Therefore, some electrons are accelerated and some are retarded. This process is called velocity modulation.

    The velocity modulation causes bunching of electrons. This bunching effect converts velocity modulation into density modulation of beam.

    The input is fed at buncher cavity and output is taken at catcher cavity.

    In a two cavity klystron only buncher and catcher cavity are used. In multi cavity klystron one or more intermediate cavities are also used.

    The features of a multicavity klystron are :

    1. Frequency range - 0.25 GHz to 100 GHz

    2. Power output - 10 kW to several hundred kW

    3. Power gain - 60 dB (nominal value)

    4. Efficiency - about 40%.

    A multicavity klystron is used in UHF TV transmitters, Radar transmitter and satellite communication.

    More questions

    • 1. A radar has a maximum range of 120 km. The maximum allowable pulse repetition frequency for unambiguous reception is

    • Options
    • A. 1250
    • B. 330
    • C. 2500
    • D. 8330
      • Discuss
    • 2. An unmodulated voltage 10 V effective is applied to a dioxide detector in which load resistance is 4 x 10-5 ohms. A micrometer shows that the rectified DC current in this resistance is 30 A. The input resistance of the detector is

    • Options
    • A. 114 kW
    • B. 336 kW
    • C. 384 kW
    • D. 455 kW
      • Discuss
    • 3. For a BJT a = 0.98, then ? =

    • Options
    • A. 0.02
    • B. 0.5
    • C. 4.9
    • D. 48
      • Discuss
    • 4. If the temperature of an extrinsic semiconductor is increased so that the intrinsic carrier concentration is doubled, then

    • Options
    • A. the majority carrier density is doubled
    • B. the minority carrier density is doubled
    • C. the minority carrier density becomes 4 times the original value
    • D. both the majority and minority carrier densities double
      • Discuss
    • 5. A cycloconverter is

    • Options
    • A. ac-dc converter
    • B. dc-ac converter
    • C. dc-dc converter
    • D. ac-ac converter
      • Discuss
    • 6. Consider the following DO statement in Fortran 77

      DO 52 N = 1, 10, 3

      The number of DO loop executions in the above statement is

    • Options
    • A. 1
    • B. 10
    • C. 3
    • D. 4
      • Discuss
    • 7. In a single phase semiconverter feeding a highly inductive load, the load current is

    • Options
    • A. sinusoidal
    • B. nearly constant
    • C. absolutely constant
    • D. rectangular
      • Discuss
    • 8. If ton and toff are the turn on and turn off times of a thyristor, then

    • Options
    • A. ton and toff are almost equal
    • B. ton >> toff
    • C. toff >> ton
    • D. ton is about twice toff
      • Discuss
    • 9. Which inverter circuit uses coupled inductors?

    • Options
    • A. Modified McMurray full bridge inverter
    • B. McMurray Bedford half bridge inverter
    • C. Modified McMurray Bedford half bridge inverter
    • D. Both (b) and (c)
      • Discuss
    • 10. If there are no permanent dipoles in a dielectric material, the dielectric constant is independent of temperature.

    • Options
    • A. True
    • B. False
      • Discuss

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