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Know the block diagrams of the crystal diode receiver,
tuned radio frequency (TRF) or straight receiver and superhet receiver.
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Know the functions of the RF amplifier, mixer, local
oscillator, IF amplifier, demodulator (detector), and audio amplifier.
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the intermediate frequency is the sum of or difference
between the RF and local oscillator frequencies.
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Know that tuned circuits in RF and IF amplifiers
select the wanted signal.
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4i Detectors
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Know how a diode detector will recover the audio from
amplitude modulated signals.
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Know that to generate the audio for CW signals a beat
frequency oscillator (BFO) is used;
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Know that for the recovery of single side band audio,
a carrier insertion oscillator (CIO) is used;
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Know that for the recovery of FM audio, a discriminator
is used.
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Know the waveforms produced in a diode AM
detector.
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Know that the automatic gain control (AGC) of a receiver
operates by sensing the strength of the received signals to keep the audio
output level fairly constant.