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  • Question

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


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

  • Correct Answer
  • 2110 kHz 

    Explanation
    A signal (image) can interfere with a superheterodyne receiver if fits the following equation.

    Image = Signal +/- 2 x I.F.

    Which says that a signal has the capacity to interfere with a superhet receiver if its frequency is equal to the signal frequency (1200 kHz in our question) plus or minus twice the IF (455 kHz in our question).

    So one possible image is: 1200 + ( 2 x 455 ) = 2110 kHz (possible).

    And the other: 1200 - ( 2 x 455 ) = 290 kHz (not likely).

    Radio Receivers problems

    Search Results

    • 1. In a radio receiver with simple AGC

    • Options
    • 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
      • Discuss
    • 2. Mechanical impedance is the ratio of

    • Options
    • A. rms force to rms velocity
    • B. rms force to rms displacement
    • C. rms velocity to rms displacement
    • D. none of the above
      • Discuss
    • 3. For the system in the given figure the characteristic equation is

    • Options
    • A.
    • B.
    • C. K(s + 1)(s + 3) = 0
    • D. s(s + 2) = 0
      • Discuss
    • 4. In a minimum phase system

    • Options
    • A. all poles lie in the left half plane
    • B. all zeros lie in the left half plane
    • C. all poles lie in the right half plane
    • D. all except one pole or zero lie in the left half plane
      • Discuss
    • 5. When a unit step voltage drives a lag network the output

    • Options
    • A. remains constant at unit step value
    • B. increases exponentially from zero to final value
    • C. decreases exponentially from 1 to 0
    • D. either (b) of (c) depending on values of R and C
      • Discuss
    • 6. 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

    • Options
    • A. 24.09 MHz
    • B. 24.54 MHz
    • C. 25.45 MHz
    • D. 25.91 MHz
      • Discuss
    • 7. Noise generated in a resistor is also known as

    • Options
    • A. partition noise
    • B. white noise
    • C. thermal noise
    • D. shot noise
      • Discuss
    • 8. The function of an AM detector circuit is to

    • Options
    • A. rectify the input signal
    • B. discard the carrier
    • C. provide audio signal
    • D. all of the above
      • Discuss
    • 9. Which of the following is same in AM and FM receivers?

    • Options
    • A. Demodulator
    • B. AGC
    • C. IF amplifier
    • D. All of the above
      • Discuss
    • 10. In a radio receiver, if the intermediate frequency is too low

    • Options
    • 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
      • Discuss

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