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ECE :: Radio Receivers

  1. The selectivity of a radio receiver is

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

  4. 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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  5. EM 84 tube is used in radio receivers as

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

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  7. Which of the following statement about receivers is false?

  8. 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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  9. Modulated carrier power in FM

  10. 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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  11. In superheterodyne receivers, the local oscillator is used to

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

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

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  15. A notch filter is sometimes used in communication receivers to

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

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

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

  20. 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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