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Radio Receivers MCQ Questions & Answers

Radio Receivers MCQs : This section focuses on the "Radio Receivers". These Multiple Choice Questions (MCQs) should be practiced to improve the Radio Receivers skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.




Question 1

It is known that noise phase modulates the FM wave. As the noise side band frequency approaches the carrier frequency, the noise amplitude

A. will increase
B. will decrease
C. will remain constant
D. will reduce to negligible value

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Question 2

The noise generated by a resistor depends upon

A. its resistance value
B. its operating temperature
C. both its resistance value and operating temperature
D. none of the above

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Question 3

EM 84 tube is used in radio receivers as

A. audio amplifier
B. RF amplifier
C. full wave rectifier
D. magic eye

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Question 4

The selectivity of a radio receiver is

A. its ability to reject adjacent unwanted signals
B. its ability to amplify weak signals
C. the frequency at which it gives maximum amplification to signal.
D. its ability to suppress noise.

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Question 5

Most popular IF for receivers tuning to 540 to 1650 kHz is

A. 433 kHz
B. 455 kHz
C. 545 kHz
D. 555 kHz

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Question 6

Which of the following oscillator is generally not used at VHF?

A. Colpitts oscillator
B. Clapp oscillator
C. Armstrong oscillator
D. Ultra Audio oscillator

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Question 7

The function of an AM detector circuit is to

A. rectify the input signal
B. discard the carrier
C. provide audio signal
D. all of the above

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Question 8

FM amplifier in a superheterodyne receiver

A. increases selectivity
B. suppresses noise
C. provides improved tracking
D. improves the rejection of the image frequency

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Question 9

In a superheterodyne receiver, the IF is 455 kHz. If it is tuned to 1200 kHz, the image frequency will be

A. 1655 kHz
B. 2110 kHz
C. 745 kHz
D. 910 kHz

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Question 10

Which are the popular IF frequencies for microwave and radar receivers operating on frequencies in the range 1 to 10 GHz

A. 30, 60 and 70 kHz
B. 3, 6 and 7 kHz
C. 30, 60 and 70 MHz
D. 3, 6 and 7 GHz

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Question 11

In a communication system, noise is most likely to affect the signal

A. at the transmitter
B. in the channel
C. in the information source
D. at the destination

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Question 12

A duplexer is a device used to

A. feed more than one receiver from a single antenna
B. connect two transmitters to the same antenna
C. connect a receiver and a transmitter to the same antenna
D. none of these

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Question 13

The selectivity of most receivers is determined largely by

A. sensitivity
B. characteristics of IF section
C. antenna direction
D. all of the above

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Question 14

In a radio receiver with simple AGC

A. the highest AGC voltage is produced between stations
B. the faster the AGC time constant, the more accurate the output
C. an increase in signal strength produces more AGC
D. the audio stage gain is normally controlled by AGC

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Question 15

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. The rejection ratio at 25 MHz will be

A. 1.116
B. 1.386
C. 2.116
D. 2.386

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Question 16

Which of the following statement about receivers is false?

A. Double conversion is used to improve image rejection
B. Double conversion is used to improve selectivity
C. Variable sensitivity is used to improve selectivity
D. Variable sensitivity is used to eliminate selective fading

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Question 17

In a ratio detector

A. the linearity is worse than in a phase discriminator
B. the output is twice that obtainable from a similar phase discriminator
C. stabilization against signal strength variations is provided
D. the circuit is the same as in a discriminator, except that the diodes are reversed

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Question 18

Which of the following statement about the amplitude limiter is not valid?

A. Leak type bias must be used
B. Output must be tuned
C. The circuit is always biased in class C, by virtue of the leak type bias
D. When the input increases past the threshold of limiting, the gain decreases to keep the output constant

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Question 19

Which of the following cannot be used to demodulate SSB?

A. Complete phase-shift generator
B. Product detector
C. Diode balanced modulator
D. Bipolar transistor balanced modulator

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Question 20

Which of the following should be used in order to prevent overloading or the last IF amplifier in a receiver?

A. Variable selectivity
B. Variable sensitivity
C. Double conversion
D. Squelch

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Question 21

A heterodyne frequency changer is called a

A. Modulator
B. Mixer
C. Demodulator
D. Frequency translator

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Question 22

A notch filter is sometimes used in communication receivers to

A. reduce receiver gain at some specific frequency
B. increase receiver gain at some specific frequency
C. made selectivity more precise
D. spread the bandwidth

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Question 23

The output of a diode detector contains

A. D.C. voltage
B. modulating signal
C. RF ripple
D. all of the above

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Question 24

In a superheterodyne receiver with an IF of 450 kHz is tuned to a signal at 1200 kHz. The image frequency is

A. 750 kHz
B. 990 kHz
C. 1650 kHz
D. 2100 kHz

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Question 25

In a radio receiver, if the intermediate frequency is too low

A. Image-frequency rejection will improve
B. Selectivity will be too sharp
C. The frequency selectivity of the local oscillator will have to be lowered
D. All of the above

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Question 26

In superheterodyne receivers, the local oscillator is used to

A. detect the modulating signal
B. amplify the received modulated carrier
C. shift the frequency of the received modulated carrier to the IF band

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Question 27

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

A. 114 kW
B. 336 kW
C. 384 kW
D. 455 kW

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Question 28

When fs is the signal frequency and fi is the intermediate frequency, then image frequency fsi is given by

A. fsi = fs - 2fi
B. fsi = fs + 2fi

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Question 29

In a radio receiver, the local oscillator is tuned to a frequency

A. lower than the incoming frequency
B. higher than the incoming frequency
C. equal to incoming frequency
D. any of the above

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Question 30

Modulated carrier power in FM

A. increases with modulating signal power
B. decreases with modulating signal power
C. is independent of the modulating signal power
D. none

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Question 31

If the intermediate frequency of a superheterodyne receiver falls within the tuning range of the receiver

A. Unsuitability will occur
B. Heterodyne whistles will be heard
C. Tuning to the frequency band immediately adjacent to the intermediate frequency will become impossible
D. All of the above

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Question 32

In a radio receiver, if the intermediate frequency is too high

A. Selectivity will be poor
B. Tracking difficulties will be least
C. Adjacent channel rejection will improve
D. All of the above will occur

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Question 33

Neutralization is used in RF amplifiers to

A. stop oscillation
B. increase bandwidth
C. improve selectivity
D. all of the above

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Question 34

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. The image frequency at 25 MHz will be

A. 24.09 MHz
B. 24.54 MHz
C. 25.45 MHz
D. 25.91 MHz

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Question 35

In a receiver, which of the following device has IF input but RF output?

A. Demodulator
B. Loudspeaker
C. Audio amplifier
D. Frequency changer

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Question 36

The noise produced by a resistor is proportional to

A. absolute temperature
B. (absolute temperature)2

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Question 37

In a superheterodyne receiver

A. the IF stage has better selectivity than RF stage
B. the RF stage has better selectivity than IF stage
C. the RF stage has same selectivity than IF stage
D. none of the above

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Question 38

In a broadcast superheterodyne receiver

A. the local oscillator operates below the signal frequency
B. local oscillator frequency is normally double the IF
C. RF amplifier normally works at kHz above the carrier frequency
D. mixer input must be tuned to the signal frequency

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Question 39

Padders are used in a receiver to

A. discard the carrier
B. facilitate tracking
C. filter the input signal
D. suppress noise

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Question 40

As compared to tuned radio frequency receivers which of the following is the advantage of using superheterodyne receivers?

A. High gain and better sensitivity
B. Better selectivity at high frequencies
C. Stability
D. Noise suppression

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Question 41

Which one of the following is not a useful quantity for comparing the noise performance of receivers?

A. Noise figure
B. Noise temperature
C. Input noise voltage
D. Equivalent noise resistance

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Question 42

Which of the following noise does not occur in transistors?

A. Partition noise
B. Shot noise
C. Flicker noise
D. Resistance noise

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Question 43

RF amplifiers are used in radio receivers for

A. improved image frequency rejection
B. improved rejection of adjacent unwanted signals
C. prevention of re-radiation of the local oscillator through the antenna of the receiver
D. all of the above

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Question 44

Transistor are free from which type of noise?

A. Resistance noise
B. Partition noise
C. Flicker noise
D. Shot noise

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Question 45

Standard AM radio broadcasts are confined to

A. MF
B. HF
C. VHF
D. UHF

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Question 46

Noise generated in a resistor is also known as

A. partition noise
B. white noise
C. thermal noise
D. shot noise

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Question 47

Which of the following is used to provide tracking between RF amplifier and local oscillator stages of receiver?

A. Variable tuning inductor
B. Ganged tuning inductor
C. Variable capacitor
D. Variable preset

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Question 48

A transmitter serial current contains

A. carrier frequencies
B. audio frequencies
C. radio frequencies
D. none of the above

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Question 49

Which of the following is same in AM and FM receivers?

A. Demodulator
B. AGC
C. IF amplifier
D. All of the above

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