a.
The antenna is disengaged from the transmitter.
b.
The baseband signal is removed from the modulator.
c.
The RF drive is removed from the high-power amplifier.
d.
The transmitter injection voltage is removed from the translator-mixer stage.
SITUATION:
One of your duties as a microwave repairman is to train new personnel in the maintenance of microwave
equipment. In a stage-by-stage discussion of a direct-angle-modulated transmitter, you use the block diagram
shown in figure 107.
Exercises 8 and 9 are based on this situation.
8.
In a direct-angle-modulated transmitter, a modulated subcarrier signal is developed in the voltage-
controlled oscillator stage. The stage that changes the frequency of the modulated subcarrier signal to the
frequency required for transmission is the
a.
diode switch.
c.
harmonic mixer.
b.
phase detector.
d.
reflex klystron.
9.
To operate correctly, the phase detector in the phase-lock loop must have a reference input. This
reference signal is derived by mixing the modulated
a.
subcarrier signal with the multiplied frequency standard output.
b.
klystron output with the multiplied frequency standard output.
c.
subcarrier signal with the modulated klystron output.
d.
klystron output with the arc detector output.
SITUATION:
To develop an understanding of the subsystems that are used in microwave systems you must also learn the
functions of the major stages within each subsystem. Assume that you must learn the functions of the stages in
the transmitter shown in figure 107 so that you will be prepared to give an orientation on the transmitter. Your
study gives you a list of points to be stressed in your orientation.
Exercises 10 through 12 are based on the above situation.
10.
Besides locking the reflex klystron, the phase-lock-loop circuit also
a.
locks the frequency standard.
b.
locks the high-power klystron amplifier.
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