12. The purpose of the filter section of the synthesizing circuit shown in
figure 6 is to
a.
generate odd harmonics.
b.
stabilize the output signal.
c.
select and purify the desired harmonic.
d.
insure that the 400-kHz signal is fed to the output section.
13. Assume that you are analyzing the block diagram of the synthesizer shown in
figure 6. The heterodyning process takes place in the
a.
400-kHz amplifier and the second mixer.
b.
first mixer and the harmonic amplifier.
c.
second mixer and the tuned filter.
d.
first mixer and the second mixer.
14. One method of preventing variations in the output frequency of a radio
transmitter is to replace its unstable oscillators with frequency synthesizers.
The transmitter's output frequency must be exact and stable in order to
a.
aid the operators.
b.
minimize transmitter downtime.
c.
prevent overcrowding of the frequency bands.
d.
prevent one radio system from interfering with another system.
15. The most common and most accurate frequency-controlling device is a
a.
crystal.
c.
b.
reactor.
d.
16. The two most common methods of stabilizing an oscillator are the
a.
linear and nonlinear methods.
b.
heterodyne and filtering methods.
c.
harmonic generation and filtering methods.
d.
phase-lock and temperature control methods.
327 L1
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