Station Assembly, Practice and Safety
transmitter, carrier, keying, and amplitude modulation fundamentals
What does chirp mean?
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A high-pitched tone which is received along with a CW signal
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Correct AnswerA small change in a transmitter's frequency each time it is keyed
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A slow change in transmitter frequency as the circuit warms up
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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?
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Add a key-click filter
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Correct AnswerKeep the power supply voltages very steady
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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?
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A crystal-controlled transmitter
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Correct AnswerA VFO-controlled transmitter
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A single-sideband transmitter
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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?
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Phase modulation
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Correct AnswerAmplitude modulation
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Amplitude-rectification modulation
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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?
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Frequency modulation
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Pulse modulation
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Correct AnswerAmplitude modulation
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Frequency shift keying
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Morse code is usually transmitted by radio as:
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a series of key-clicks
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a continuous carrier
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Correct Answeran interrupted carrier
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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:
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loss of modulation in the transmitted signal
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the driver stage will not deliver power to the final
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Correct Answerexcessive heat produced in the final transmitter stage
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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:
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smaller DC current drain
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lower modulation percentage
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Correct Answerreduced antenna radiation
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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:
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become over modulated
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generate key-clicks
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Correct Answerdrift in frequency
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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?
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Correct AnswerIt has been dissipated as heat loss
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It has been used to provide greater efficiency
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It has been used to provide negative feedback
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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:
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is lost in the feed line
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Correct Answerappears as heat dissipation
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is due to oscillating
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radiates from the antenna
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