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.
IF (JCOKE - 3 * LPEPSI) 5, 6, 7
5 JCOKE = JCOKE + 5
6 JCOKE = JCOKE + 8
7 JCOKE = JCOKE + 11
The value of JCOKE after the execution of above statement will be
Options
- A. 103
- B. 106
- C. 109
- D. none of the above
Discuss
Correct Answer: 103
Explanation:
Since (J COKE - 3 x L PEPSI) is negative, statement 5 is executed and the result is 98 + 5 = 103.
- 4. Read the following statements about files in Pascal
- A file is a data structure which consists of a sequence of components of the same type.
- The number of components in a file is variable.
- The components in a file can be accessed only sequentially starting from the beginning of the file.
Which of the above are correct?
Options
- A. All
- B. 1 and 2 only
- C. 2 and 3 only
- D. 1 and 3 only
Discuss
Correct Answer: All
Explanation:
All statements are true.
- 5. In a backward wave oscillator the wave travelling along the line winds itself back and forth
Options
- A. True
- B. False
Discuss
Correct Answer: True
Explanation:
It is somewhat similar to TWT and can deliver microwave power over a wide frequency band.
It has an electron gun and a helix structure. However the interaction between electron beam and RF wave is different than in TWT.
The growing RF wave travels in opposite direction to the electron beam.
The frequency of wave can be changed by changing the voltage which controls the beam velocity.
Moreover the amplitude of oscillations can be decreased continuously to zero by changing the beam current.
It features are:
1. Frequency range - 1 GHz to 1000 GHz.
2. Power output - 10 mV to 150 mW (continuous wave) 250kW (pulsed).
It is used as signal source in transmitters and instruments.
- 6. In the series circuit shown in figure, for series resonance, the value of the coupling coefficient, K will be

Options
- A. 0.25
- B. 0.5
- C. 0.1
- D. 1
Discuss
Correct Answer: 0.25
Explanation:
Mutual inductance wm = ?k L1L2
⟹ m = k. 2. 8j2 = 4k. j
Z = 20 - j10 + j2 + j6 + 2.4kj - 2j + 8kj = 0 at resonance
⟹ -2 = -8k
k = 1/4 ⟹ 0.25 .
- 7. Match the following:
List I
List II
A.
hie
1.
siemens
B.
hoe
2.
no units
C.
hfe
3.
ohms
Options
- A. A-1, B-2, C-3
- B. A-3, B-1, C-2
- C. A-2, B-1, C-3
- D. A-3, B-2, C-1
Discuss
Correct Answer: A-3, B-1, C-2
- 8. The number of leads in a power semiconductor diode are
Options
- A. 2
- B. 3
- C. 4
- D. 2 or 3
Discuss
Correct Answer: 2
Explanation:
A diode has 2 leads irrespective of its rating.
- 9. As compared to their values in free space
Options
- A. velocity of electric wave in dielectric is smaller but wave length of electric wave is more
- B. both velocity and wave length of electric wave in dielectric are higher
- C. both velocity and wave length of electric wave in dielectric are smaller
- D. wave length of electric wave is less but velocity is more in dielectric
Discuss
Correct Answer: both velocity and wave length of electric wave in dielectric are smaller
- 10. Match the following:
List I
List II
A.

1.
a constant
B.
e-j?
2.
exponential function
C.

3.
t multiplied exponential function
D.
k ?(?)
4.
rectangular pulse
5.
impulse function
Options
- A. A-4, B-5, C-3, D-1
- B. A-4, B-5, C-3, D-2
- C. A-3, B-4, C-2, D-1
- D. A-3, B-4, C-2, D-5
Discuss
Correct Answer: A-4, B-5, C-3, D-1
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