Learning outcomes of this part
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Know the block diagrams of CW, AM, SSB and FM
transmitters.
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the functions of the microphone amplifier, AM/FM
modulators, SSB balanced modulator, side band filter, oscillator, power amplifier
and low pass filter.
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the relative advantages and disadvantages of a crystal
oscillator and a VFO.
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the resonant frequency of the tuned circuit in a VFO
determines the frequency of oscillation.
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the stability of an oscillator can be improved by
rigid mechanical construction, screening the oscillator enclosure, and using
a regulated DC supply.
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a lack of stability (drift) may result in operation
outside the amateur bands.
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most modern oscillators are digital synthesizers,
which are very stable.
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