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Continue Part III of the Series
101. It is the width of frequencies within the spectrum occupied by a signal and used by the
signal for conveying information.
A. Band
B. Bandwidth
C. Electronic spectrum
D. Frequency band
102. Which transmit only one sideband?
A. H3E
B. C3F
C. A3E
D. B8E
103. ______ is kind of modulation in which the modulated wave is always present.
A. Carrier modulation
B. Continuous modulation
C. Log-periodic modulation
D. Square-wave modulation
104. A type of modulation in which no signal is present between pulses.
A. Pulse modulation
B. FSK
C. QAM
D. PAM
105. What describes the amount of amplitude change present in an AM waveform?
A. Percent modulation
B. Modulation constant
C. Envelope of modulation
D. Coefficient of modulation
106. _______ is a form of amplitude distortion introduced when the positive and negative
alternations in the AM modulated signals are not equal.
A. Envelope distortion
B. Spurious emission
C. Carrier shift
D. Johnson noise
107. What is the advantage of phase modulation over direct FM frequency modulation?
A. Multipliers can be used
B. The deviation is smaller
C. Simplicity and practicality
D. The oscillator is crystal-controlled
108. If the spectrum is shifted in frequency with no other changes, this is known as
A. Frequency multiplication
B. Sideband movement
C. Baseband reorientation
D. Frequency translation
109. A device which is capable of causing frequency translation
A. High-Q tank circuit
B. Balanced modulator
C. Low-Q tank circuit
D. IF strip
110. If the frequency of each component in a signal spectrum is increased by the same
fixed amount, this known as
A. Modulation
B. Frequency translation
C. Up conversion
D. Both B and C
111. A particular amplifier is designed to be a frequency doubler. If the input signal
frequency is 15.4 MHz, a circuit in the output will be tuned to
A. 7.7 MHz
B. 15.4 MHz
C. 30.8 MHz
D. 61.6 MHz
112. A sine wave of 293 MHz is phase-modulated to achieve a maximum phase deviation
of 0.2 radian. After passing through a frequency tripler, the maximum phase deviation will
be
A. 0.2 radian
B. 0.3 radian
C. 0.4 radian
D. 0.6 radian
113. Any device to be used as a frequency multiplier must be
A. Active
B. Passive
C. Linear
D. Nonlinear
114. A particular amplifier circuit used for frequency doubling.
A. Push-push
B. Push-pull
C. Pull-push
D. Pull-pull
115. Frequency division is useful in the implementation of a
A. AM demodulator
B. Frequency synthesizer
C. AGC circuit
D. FM demodulator
116. Frequency division by 12 will require how many flip-flops in the counter?
A. 3
B. 4
C. 6
D. 12
117. Identify an electronic device, not specifically designed for the purpose, which can be
used as a phase detector.
A. Wien bridge
B. Colpitts oscillator
C. Balanced modulator
D. Butterworth filter
118. A particular frequency synthesizer contains only a single crystal. What words describe
this synthesizer?
A. Crystal modulated
B. Inexact
C. Indirect
D. Deficient
119. A recognizable feature of a CW transmitter is
A. Keyed transmitter
B. Power amplification
C. Frequency generation
D. All of these
120. The term “pulling” refers to
A. The change of the crystal oscillator frequency by loading
B. One half-cycle operation of a push-pull amplifier
C. Loading on the transmitter caused by the antenna connection
D. Reduction of the power supply terminal voltage as the transmitter is keyed.
121. When frequency modulation is achieved by initial phase modulation, this is called
A. Angular modulation
B. Direct FM
C. Indirect FM
D. Indirect synthesis
122. A disadvantage of direct FM is the need for
A. AGC
B. AFC
C. A frequency synthesizer
D. Phase modulation
123. Direct FM can be achieved by
A. A reactance tube modulator
B. A varactor diode
C. And AGC circuit
D. Both A and B
124. A receiver in which all RF amplifier stages require manual tuning to the desired RF is
called
A. Superheterodyne
B. Autodyne
C. TRF
D. AFC
125. Why is it often necessary to precede the demodulator by amplifier stages in a
receiver?
A. To improve fidelity
B. To reduce receiver noise
C. To eliminate image response
D. Weak antenna signals
126. A serious disadvantage of the TRF receiver.
A. Bandwidth variations over the tuning range
B. The weight and cost
C. The requirements for a closely regulated power supply
D. The requirements for a half-wave antenna
127. Identify which is not a part of a superheterodyne receiver.
A. Local oscillator
B. Modulator
C. IF amplifier
D. Demodulator
128. Which major element will not be found in every superheterodyne receiver?
A. R–F amplifier
B. Mixer
C. Local oscillator
D. IF amplifier
129. Which major element of a superheterodyne receiver must be nonlinear?
A. R-F amplifier
B. Mixer
C. Local oscillator
D. IF amplifier
130. The change of the modulated carrier frequency from the original RF to the IF of the
superheterodyne receiver is known as
A. Frequency multiplication
B. Frequency allocation
C. Frequency substitution
D. Frequency translation
131. The key to achieving receiver sensitivity is the reduction of
A. Image response
B. Mixer harmonic products
C. Spurious frequency response
D. Internal noise
132. Which of the following receiver design objectives is not impossible?
A. Elimination of galactic noise
B. Elimination of atmospheric noise
C. Elimination of man-made noise
D. Reduction of receiver internal noise
133. In comparing the S/N ratio for the input to the receiver with the S/N ratio for the output,
the latter is
A. Smaller
B. The same
C. Greater
D. Infinite
134. The characteristic of a receiver that specifies the self-generated noise.
A. Noise immunity
B. Noise factor
C. Noise figure
D. Noise margin
135. An FM receiver with an I-F of 10.7 MHz is tuned to 98.7 MHz. What is the numerical
value of the image frequency?
A. 77.3 MHz
B. 88.0 MHz
C. 109.4 MHz
D. 120.1 MHz
136. A source of RF interference exists at 109.9 MHz. For which frequency in the FM
broadcast band will this be the image frequency?
A. 21.4 MHz
B. 88.5 MHz
C. 99.2 MHz
D. 110.7 MHz
137. The ratio of the superheterodyne receiver response at the desired carrier frequency to
that at the image frequency is called
A. The sensitivity
B. The selectivity
C. The image frequency
D. The image rejection ratio
138. The core of an IF transformer usually contains
A. Teflon
B. Computer nylon
C. Powdered iron
D. Laminated steel
139. Shape factor is a measure of
A. Bandwidth
B. Skirt steepness
C. Coupling coefficient
D. Critical coupling
140. _______ is the function which tends to maintain the sound volume level of a voice
receiver nearly constant for a large signal strength range.
A. Squelch
B. Muting
C. AGC
D. AFC
141. The function which tends to silence the receiver in the absence of transmitted carrier.
A. Squelch
B. Muting
C. AGC
D. AFC
142. What device is incorporated in a communications receiver to reduce impulse noise?
A. Front-end processor
B. Squelch circuit
C. AGC
D. Noise blanker
143. What type of signal in which a receiver selectivity of 2.4 kHz in the I-F circuitry is
optimum?
A. FM voice
B. Double-sideband AM voice
C. FSK data
D. SBB voice
144. If the input to a detector stage is an amplitude-modulated (A3E) IF signal then the
output from the stage is
A. A lower frequency carrier
B. The audio voice information
C. A Morse-code signal
D. The upper or lower set of sidebands
145. In a capacitive type, reactance-tube modulator connected across an oscillator tuned
circuit, a more negative voltage on the grid of the reactance tube will cause
A. An increase of the oscillator frequency
B. An decrease of oscillator frequency
C. An increase of the reactance-tube capacitance
D. An increase of the reactance tube ac plate current
146. The limiting condition for sensitivity in a communications receiver is
A. The noise floor of the receiver
B. Power supply output ripple
C. The two-tone intermodulation distortion
D. The input impedance to the detector
147. When a communications receiver is tuned to a strong signal, the AGC bias is
measured and found to be zero. The fault cannot be caused by a/an
A. Defective IF stage
B. Defective local oscillator
C. Defective RF stage
D. Open circuit in the AGC’s filter capacitor
148. The term used to refer to the condition where the signals from a very strong station
are superimposed on other signals being received
A. Cross-modulation interference
B. Intermodulation interference
C. Receiver quieting
D. Capture effect
149. The limiter stage of an FM receiver
A. Behaves as a low-pass filter
B. Limits the amplitude of the IF signal to the required level
C. Behaves as a high-pass filter
D. Behaves as a bandstop filter
150. Motorboating (low-frequency oscillations) in an amplifier can be stopped by
A. Grounding the screen grid
B. Connecting a capacitor between the B+ and lead ground
C. By passing the screen grid resistor with a 0.1 μF capacitor
D. Grounding the plate