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السؤال 398

What is the function of a reactance modulator?

  1. Produce PM or FM signals by varying a resistance
  2. Produce AM signals by varying an inductance
  3. Produce AM signals by varying a resistance
  4. Produce PM or FM signals by varying a capacitanceالإجابة الصحيحة

الشرح

A reactance modulator presents a reactance that changes with the applied audio voltage, in practice a voltage-variable-capacitance semiconductor device controlled by bias. Changing the tank capacitance shifts frequency or phase, producing FM or PM; varying a resistance would change amplitude and Q instead.

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