In a three cavity klystron amplifier, the oscillations are excited in input cavi

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Question
In a three cavity klystron amplifier, the oscillations are excited in
Options
A. input cavity
B. output cavity
C. intermediate cavity
D. both (a) and (b)

Correct Answer

intermediate cavity

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

4. As compared to an ordinary semiconductor diode, a Schottky diode
Options
A. has higher reverse saturation current
B. has higher reverse saturation current and higher cut in voltage
C. has higher reverse saturation current and lower cut in voltage
D. has lower reverse saturation current and lower cut in voltage

6. The total field developed by an antenna array at a distant point is
Options
A. phasor sum of fields produced by individual antennas of the array
B. algebraic sum of fields produced by individual antennas of the array
C. either (a) or (b) depending on type of array
D. neither (a) nor (b)

7. A standard cell of 1.0185 V is used with a slide wire potentiometer. The balance was obtained at 60 cm. When an unknown emf was connected, the balance was obtained at 82 cm. The magnitude of unknown emf is
Options
A. 1.39 V
B. 0.75 V
C. 13.9 V
D. 7.45 V

8. The number of valence electrons in donor impurity are
Options
A. 5
B. 4
C. 3
D. 1

9. Assertion (A): A DIAC has four layers but only two terminals.
Reason (R): A DIAC can conduct in both directions.
Options
A. Both A and R are correct and R is correct explanation of A
B. Both A and R correct but R is not correct explanation of A
C. A is correct but R is wrong
D. A is wrong but R is correct

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