Discussion
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- Question
In a broadcast superheterodynes receiver having no RF amplifier, the loaded Q of the antenna coupling circuit is 100. If the intermediate frequency is 455 kHz. In receivers operating upto the limit of shortwave broadcasting the local oscillator often used is
Options- A. Armstrong oscillator
- B. Colpitts oscillator
- C. Clapp oscillator
- D. Ultra Audio oscillator
- Correct Answer
- Armstrong oscillator
- 1. Which power amplifier can deliver maximum load power?
Options- A. Class A
- B. Class AB
- C. Class B
- D. Class C Discuss
- 2. The attraction between the nucleus and valence electron of copper atom is
Options- A. zero
- B. weak
- C. strong
- D. either zero or strong Discuss
- 3. Wood is a diamagnetic material.
Options- A. True
- B. False Discuss
- 4. In a receiver, which of the following device has RF input but IF output?
Options- A. Loudspeaker
- B. Frequency changer
- C. Demodulator
- D. Audio amplifier Discuss
- 5. Fidelity of a receiver represents
Options- A. the sensitivity expressed in terms of voltage that must be applied to the receiver input to give a standard output
- B. the extent to which the receiver is capable of distinguishing between the desired signal and other frequencies
- C. the variation of the output with the modulation frequency when the output impedance is a resistance
- D. none of the above Discuss
- 6. As per BIS there are 6 accuracy classes of instruments.
Options- A. True
- B. False Discuss
- 7. In superheterodyne receivers, the local oscillator is used to
Options- A. detect the modulating signal
- B. amplify the received modulated carrier
- C. shift the frequency of the received modulated carrier to the IF band Discuss
- 8. A receiver having an RF amplifier and an IF of 450 kHz, has Q of the coils 65 and an incoming frequency of 1200 kHz. The image rejection of the receiver is
Options- A. 5870
- B. 3655
- C. 236
- D. 13.3 Discuss
- 9. A dynamometer wattmeter is connected in ac circuit. The reading will be
Options- A. V-A product
- B. average power
- C. peak power
- D. instantaneous power Discuss
- 10. In an R-C series circuit excited by a voltage E, the charge across capacitor at t = 0+ is
Options- A. 0
- B. CE
- C. CE (1 - e-t/RC)
- D. none of the above Discuss
More questions
Correct Answer: Class C
Explanation:
Since efficiency of class C operation is high, maximum load power is delivered.
Correct Answer: weak
Explanation:
The valence electron, in copper atom, can be easily detached from nucleus.
Correct Answer: False
Correct Answer: Frequency changer
Correct Answer: the variation of the output with the modulation frequency when the output impedance is a resistance
Correct Answer: False
Explanation:
There are 8 classes of accuracy as per BIS.
Correct Answer: shift the frequency of the received modulated carrier to the IF band
Correct Answer: 236
Correct Answer: average power
Explanation:
Wattmeter measures average power over a cycle.
Correct Answer: 0
Explanation:
Voltage across a capacitor cannot change instantaneously.
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