23
3-38. Which of the following statements
describes cross modulation?
1. Degenerative feedback that causes a
circuit to oscillate
2. Overmodulation that produces an
echo
3. The signal from one channel that
modulates the signal on an adjacent
channel
4. Oscillation that is caused by system
misalignment
3-39. Distortion caused by excessive
regenerative feedback is called
1. echo
2. crosstalk
3. detected distortion
4. parasitic generation
3-40. When using a two-tone test to detect
intermodulation distortion, what is the
ideal indication you should see on a
spectrum analyzer?
1. An exact reproduction of the input
frequencies
2. The sum and difference of the input
frequencies
3. A single frequency with the amplitude
equal to the sum of the input
frequencies
4. The beat frequency of the two inputs
3-41. Which of the following actions
minimizes the effects of intermodulation
distortion?
1. Using proper antenna spacing
2. Shielding components and circuitry
3. Using parasitic suppression circuits
4. All of the above
3-42. At what point does an amplitude-
modulated signal begin to produce
distortion?
1. Below 50% modulation
2. At 65% modulation
3. At 95% modulation
4. Above 100% modulation
3-43. To obtain 100% amplitude modulation of
an rf carrier with a sine wave, the
modulating power must equal what
minimum percent of the rf carrier power?
1.
10%
2.
15%
3.
25%
4.
50%
3-44. The damping of a meter movement that
is being used to measure modulation has
which of the following disadvantages?
1. The frequency response of the meter
is reduced
2. The accuracy of the meter movement
is reduced
3. An average reading does not disclose
transient overmodulation
4. The amount of current required to
drive the meter is reduced
3-45. Which of the following modulation
patterns can be observed on an
oscilloscope?
1. Wave-envelope and trapezoidal
2. Lissajous and wave-envelope
3. Time division and frequency division
4. Lissajous and trapezoidal
3-46. The frequency response of most
oscilloscopes limits the capability of
measuring percentage of modulation to
which of the following frequency bands?
1. Lf and hf
2. Slf and shf
3. Uhf
4. Vhf
