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Subelement 3
Station Assembly, Practice and Safety
Section 3-11
transmitter, carrier, keying, and amplitude modulation fundamentals
What does chirp mean?
  • A high-pitched tone which is received along with a CW signal
  • Correct Answer
    A small change in a transmitter's frequency each time it is keyed
  • A slow change in transmitter frequency as the circuit warms up
  • An overload in a receiver's audio circuit whenever CW is received
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What can be done to keep a CW transmitter from chirping?
  • Add a key-click filter
  • Correct Answer
    Keep the power supply voltages very steady
  • Keep the power supply current very steady
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What circuit has a variable-frequency oscillator connected to a driver and a power amplifier?
  • A crystal-controlled transmitter
  • Correct Answer
    A VFO-controlled transmitter
  • A single-sideband transmitter
  • A packet-radio transmitter
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What type of modulation system changes the amplitude of an RF wave for the purpose of conveying information?
  • Phase modulation
  • Correct Answer
    Amplitude modulation
  • Amplitude-rectification modulation
  • Frequency modulation
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In what emission type does the instantaneous amplitude (envelope) of the RF signal vary in accordance with the modulating audio?
  • Frequency modulation
  • Pulse modulation
  • Correct Answer
    Amplitude modulation
  • Frequency shift keying
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Morse code is usually transmitted by radio as:
  • a series of key-clicks
  • a continuous carrier
  • Correct Answer
    an interrupted carrier
  • a voice-modulated carrier
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A mismatched antenna or feedline may present an incorrect load to the transmitter. The result may be:
  • loss of modulation in the transmitted signal
  • the driver stage will not deliver power to the final
  • Correct Answer
    excessive heat produced in the final transmitter stage
  • the output tank circuit breaks down
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One result of a slight mismatch between the power amplifier of a transmitter and the antenna would be:
  • smaller DC current drain
  • lower modulation percentage
  • Correct Answer
    reduced antenna radiation
  • radiated key-clicks
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An RF oscillator should be electrically and mechanically stable. This is to ensure that the oscillator does not:
  • become over modulated
  • generate key-clicks
  • Correct Answer
    drift in frequency
  • cause undue distortion
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The input power to the final stage of your transmitter is 200 watts and the output is 125 watts. What has happened to the remaining power?
  • Correct Answer
    It has been dissipated as heat loss
  • It has been used to provide greater efficiency
  • It has been used to provide negative feedback
  • It has been used to provide positive feedback
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The difference between DC input power and RF output power of a transmitter RF amplifier:
  • is lost in the feed line
  • Correct Answer
    appears as heat dissipation
  • is due to oscillating
  • radiates from the antenna
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