Radio receivers and transmitters - Electronics Engineering test questions

Radio receivers and transmitters - Electronics Engineering test questions

(1) The stage that contains the secondary of the last IF transformer is

(A) Detector
(B) Mixer
(C) Oscillator
(D) None of the above

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(2) Two waveforms are 180° out of phase. What will be the beat frequency at 276 MHz?

(A) 2.76 MHz
(B) 276 KHz
(C) 455 KHz
(D) Zero

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(3) The frequency of local oscillator in a superheterodyne receiver is

(A) Equal to incoming signal
(B) Higher than incoming signal
(C) Less than incoming signal
(D) Half that of incoming signal

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For questions 4 and 5 refer to the data given below:

Consider a superheterodyne receiver with no RF amplifier. The loaded Q of the antenna coupling circuit at the input of the mixer is 100. The intermediate frequency is 445 KHz

(4) At 1000KHz the image frequency will be

(A) 1910KHz
(B) 1000KHz
(C) 455KHz
(D) 2000KHz

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(5) At 100 KHz the rejection ratio will be

(A) 39.5
(B) 100
(C) 138.6
(D) 80.2

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(6) The term “Delayed AGC” implies Application of AGC

(A) After some time lag
(B) Only when signal strength has increased beyond a specified value
(C) To the last stage of receiver
(D) After switch of on-off switch

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(7) In a transistor receiver, let a FET is used as the first AF amplifier. This will have the effect of

(A) Reducing the effect of negative peak clipping
(B) Improving the selectivity of the receiver
(C) Reducing the effect of noise at low modulation depths
(D) Improving the effectiveness of the AGC

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(8) Three-point tracking is achieved with

(A) Variable selectivity
(B) Double spotting
(C) Double conversion
(D) The padder capacitor

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(9) The effect of transit time noise is significant is

(A) Medium frequency
(B) Low frequency
(C) High frequency
(D) All of the above

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(10) ___________ is basically a trimmer

(A) Inductor
(B) Capacitor
(C) Insulator
(D) Variable resistor

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(11) In FDM receivers to separate channels

(A) Integrators are used
(B) Differentiators are used
(C) Band stop filters are used
(D) Band pass filters are used

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(12) Consider an AM radio with IF = 455KHz. The oscillator frequency for tuning in 710 KHz is

(A) 1000 KHz
(B) 255 KHz
(C) 150.5 KHz
(D) 1165 KHz

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(13) ____________frequency divider is not free running and requires synchronization by sine waves

(A) Regenerative
(B) Bistable
(C) Astable multivibrator
(D) None of the above

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(14) The distance between the transmitting antenna and the point where the sky wave is first received after returning to the earth is known as

(A) Skip distance
(B) Radial distance
(C) Effective distance
(D) Line-of-sight distance

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(15) Which one of the following is not present in the output of a diode detector?

(A) RF ripple
(B) Modulating signals
(C) Output signal
(D) DC voltage

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(16) The crystal frequency that is used only at high frequencies is

(A) Crystal gate
(B) Ladder
(C) Full lattice
(D) Half lattice

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(17) In a filter response the shape factor

(A) Determines the adjacent channel selectivity of the filter
(B) Is equal to the 60dB bandwidth of a mechanical filter
(C) Cannot be applied to crystal filters
(D) Is the same as the peak to valley ratio

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(18) In a receiver to prevent overloading of the last IF amplifier one should use

(A) Double conversion
(B) Squelch
(C) Variable selectivity
(D) Variable sensitivity

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(19) In an FM transmitter what will happen if the modulation stage is followed by a frequency multiplied stage?

(A) Lesser frequency deviation
(B) Higher frequency deviation
(C) Distortion
(D) None

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(20) Consider a plate modulated class C amplifier. Plate supply voltage = V, the maximum plate cathode voltage =

(A) V
(B) 4V
(C) 3V
(D) 230V

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(21) Trough a mixer when an FM signal with a deviation d is passed its frequency is reduced five fold. The deviation in the output of the mixer is

(A) Indeterminate
(B) 5d
(C) d
(D) d/5

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(22) In a plate modulated class C amplifier leak type bias is used to

(A) Prevent excessive grid current
(B) Increase the bandwidth
(C) Prevent over modulation
(D) Prevent tuned circuit damping

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(23) Long wave broadcast transmitters are used in

(A) Temperate countries
(B) Tropical countries
(C) Everywhere
(D) Nowhere

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(24) If the transmitter signal is over modulated it is corrected by adjusting

(A) RF oscillator
(B) Speech amplifier
(C) Power amplifier
(D) Frequency doubler

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(25) Which one of the following statement is true?

(A) VODAS is used in all radio broadcast systems
(B) A volume compressor clips the signal when it reaches predetermine value
(C) Volume compressor is always used in a radio broadcast transmitter
(D) Modern AM broadcast transmitters use high power level modulation system

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