41. The controlled oscillator synthesizer is sometimes preferred to the direct one because—
    

1. 1. It is a simpler piece of equipment
      

   
   
   

   2. Its frequency stability is better
      

   
   
   

   3. It does not require crystal oscillators
      

   
   
   

   4. It is relatively free of spurious frequencies

   
   
   

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1. View Hint View Answer Discuss in Forum

   The controlled oscillator synthesizer is sometimes preferred to the direct one because it is relatively free of spurious frequencies.

   Correct Option: D

   The controlled oscillator synthesizer is sometimes preferred to the direct one because it is relatively free of spurious frequencies.

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42. Indicate the false statement in connection with communications receivers—
    

1. 1. The noise limiter cuts off the receiver’s output during a noise pulse.
      

   
   
   

   2. A product demodulator could be used for the reception of Morse code
      

   
   
   

   3. Double conversion is used to improve image rejection
      

   
   
   

   4. Variable sensitivity is used to eliminate selective fading

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   NA

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43. In a ratio detector—
    

1. 1. The linearity is worse than in a phase discriminator
      

   
   
   

   2. Stabilization against signal strength variations is provided
      

   
   
   

   3. The output is twice that obtainable from a similar phase discriminator
      

   
   
   

   4. The circuit is the same as in a discriminator, except that the diodes are reversed

   
   
   

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1. View Hint View Answer Discuss in Forum

   In a ratio detector the linearity is worse than in a phase discriminator.

   Correct Option: A

   In a ratio detector the linearity is worse than in a phase discriminator.

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

1. 1. 750 kHz
      

   
   
   

   2. 900 kHz
      

   
   
   

   3. 1650 kHz
      

   
   
   

   4. 2100 kHz

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   NA

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45. To prevent overloading of the last IF amplifier in a receiver, one should use—
    

1. 1. Squelch
      

   
   
   

   2. Variable sensitivity
      

   
   
   

   3. Variable selectivity
      

   
   
   

   4. Double conversion

   
   
   

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1. View Hint View Answer Discuss in Forum

   To prevent overloading of the last IF amplifier in a receiver, one should use variable sensitivity.

   Correct Option: B

   To prevent overloading of the last IF amplifier in a receiver, one should use variable sensitivity.

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