c. no stabilizing circuits to tune, no limiter stages, and fewer components.
d. no limiter stages, fewer components, and more accurate timing.
9. Assume that an FM transmitter is equipped with a motor-control AFC system.
If the master oscillator drifts to a frequency above the center frequency, the AFC
system corrects the situation by
a. modulating the oscillator with a stable frequency.
b. changing the capacitance across the master oscillator tank circuit.
c. injecting an increased amount of inductive reactance across the master
oscillator.
d. applying two out-of-place low-frequency signals to the master oscillator.
10. Compared with an indirect
FM
transmitter,
an
advantage
of
a
direct
FM
transmitter is that it generally
a. requires fewer frequency multiplier stages.
b. produces a lower frequency deviation at the oscillator.
c. operates without automatic frequency control.
d. produces a more stable output frequency.
11. An RF amplifier with tuned circuits in the grid and plate will tend to
oscillate if the grid circuit receives positive feedback from the plate circuit.
The driver stage (V8) of the FM transmitter shown in figure 99 of TM 11-668 is kept
from oscillating by the
a. negative feedback voltage that is coupled through C18.
b. transformer coupling between the grid and plate-tank circuits.
c. degenerative feedback voltage developed by C18 and coupled to the input
circuit by C17.
d. shield formed between the input and output circuits when the stage is
operated in the grounded-grid arrangement.
12. The reason for grounding the center of L7 for RF in figure 100 of TM 11-668
and removing the outputs from the top and bottom of L7 is that it provides a means
for developing the
a. bias voltage needed for V11 and V12.
b. out-of-phase input voltages needed for V11 and V12.
323 L4
44
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