PINOYBIX MODULATION
B. vary in frequency with modulation
1. ______ is the maximum sideband suppression value using
C. vary in frequency and amplitude with
filter system.
wideband modulation
A. 50 dB
B. 60 dB
9. The process of impressing intelligence on the carrier is
C. 40 dB
called
D. 30 dB
D. is not immune to noise
A. modulation
2. _______ determines the number of sideband components in
B. detection
FM.
C. mixing
D. impression
A. carrier frequency
B. modulation frequency
10. ______ is an electronic instrument used to show both the
C. modulation index
carrier and the sidebands of a modulated signal in the
D. deviation ratio
frequency domain.
3. One of the following transmits only one sideband.
A. spectrum analyzer
A. H3E
B. oscilloscope
B. R3E
C. digital counter
C. A3E
D. frequency counter
D. B8E
4. What produces the sidebands on FM?
11. What part of the carrier is varied by the intelligence during modulation in an AM system?
A. signal amplitude
A. phase
B. carrier harmonics
B. frequency
C. baseband frequency
C. amplitude
D. broadband frequency
D. both a and c
5. Which test instrument displays the carrier and the s idebands
12. The difference between the RF carrier and the modulating
amplitude with frequency to frequency?
signal frequencies is called the
A. oscilloscope
A. USB
B. spectrum analyzer
B. LSB
C. frequency analyzer
C. Sideband
D. amplitude analyzer
D. Carrier frequency
6. Mixer is also known as a ________.
13. What stage in a radio transmitter isolates the oscillator from
A. modulator
B. suppressor
A. Oscillator
C. converter
B. Buffer
D. beater
C. Separator
D. Mixer
7. Which one of the following emission transmits the lower sideband and half of the upper sideband?
the load?
14. The frequency of the unmodulated carrier in FM s ystem is
A. A5C
A. modulating frequency
B. J3E
B. center frequency
C. A3J
C. carrier frequency
D. A3H
D. deviation frequency
8. An FM receives signal ______.
A. vary in amplitude with modulation
15. The ratio of maximum deviation to the maximum modulating frequency is called
A. carrier swing
B. deviation ratio
22. To generate an SSB or DSB signal one must use a circuit
C. modulation factor
known as
D. modulation index
16. A carrier signal has
D. Armstrong system
A. filter modulator
B. ring modulator
A. constant amplitude
C. balanced modulator
B. a frequency of 20 kHz and above
D. reactance modulator
C. a varying amplitude
D. the information content
23. Which is the first radio receiver?
A. TRF receiver
17. The modulated peak value of a signal is 125 V and the
B. Superheterodyne receiver
unmodulated carrier value is 85 V. W hat is
C. Crystal radio receiver
the modulation index?
D. Heterodyne receiver
A. 0.47
24. An interfering signal with a frequency equal to the received
B. 0.68
signal plus twice the IF is called
C. 0.32
A. image frequency
D. 1.47
B. center frequency
18. An 891 kHz carrier having an amplitude of 80 V is
C. rest frequency
modulated by a 4.5 kHz audio signal having an amplitude of 45
D. interference frequency
V. Themodulation factor is
25. Double sideband full carrier emission type
A. 0.56
A. A3J
B. 0.65
B. H3E
C. 1.78
C. R3A
D. 1.25
D. A3E
19. What is the modulation index of an FM signal having a
26. Single sideband reduced carrier emission type
carrier swing of 75 kHz when the modulating signal has
A. H3E
frequency of 3 kHz?
B. R3E
A. 25
C. J3E
B. 12.5
D. B8E
C. 0.04
D. 0.08
27. A single sideband suppressed carrier emission type.
A. H3e
20. In a FM system, if modulation index is doubled by having
B. R3E
the modulating frequency, what will be the effect on the
C. J3E
maximum deviation?
D. B8E
A. No effect
B. Maximum deviation doubles
A. H3E
C. Decreases by ½
B. R3E
D. Increases by ¼
C. J3E
D. B8E
21. Which of the following is considered as an indirect method of generating FM?
28. Independent sideband emission type
29. Vestigial sideband emission type
A. Reactance modulator
A. C3F
B. Balanced modulator
B. J3E
C. Varactor diode modulator
C. R3E
D. B8E
30. Single sideband full carrier emission type.
D. B3E
38. AM transmission power increases with ________.
A. R3E
A. Frequency
B. H3E
B. Source
C. J3E
C. Load
D. B8E
D. Modulation
31. Phase modulation emission type.
39. _______ locks the FM receiver to a stronger signal.
A. F3E
A. Hall effect
B. F3C
B. Capture effect
C. F3F
C. Image frequency
D. G3E
D. Homing
32. Which one is not an advantage of SSB over AM?
40. What is the highest percentage of modulation for AM?
A. Power saving
A. 50 %
B. Requires half the bandwidth
B. 75 %
C. Wider area of reception
C. 100 %
D. Better fidelity
D. 80 %
33. The advantage of a high level modulated AM transmitter is
41. In FM, the Carson’s Rule states that the bandwidth is equal
A. Less audio power required
B. Better fidelity
A. Carrier signal
C. Higher value of operating power
B. Modulating signal
D. Less distortion
C. Frequency deviation
D. Image frequency
34. The advantage of a low-level modulated AM transmitter is
to twice the sum of the modulating frequency and ______.
A. Less audio power required
42. What is the carrier swing of an FM transmitter when
B. Better fidelity
modified by 75%?
C. Higher value of operating power
A. 53.2 kHz
D. Less distortion
B. 48 kHz
35. _____ is the bad effect caused by overmodulation in AM
C. 56.25 kHz
transmission.
D. 112.5 kHz
A. Increase in noise
B. Deviation in the operating frequency
A. Single sideband suppressed carrier
C. Interface to other radio services
B. Frequency modulation
D. Decrease in the output power
C. Pulse-position modulation
D. Amplitude shift keying
36. Which characteristic of a radio receiver refers to its ability to reject an unwanted signal?
43. The modulation system inherently more resistant to noise
44. Subcarriers that are arranged so that the c hannels
A. Sensitivity
occupying adjacent frequency bands with some frequency
B. Selectivity
space between them is known as
C. Fidelity
A. Guard bands
D. Quality
B. AM bands
C. Band gap
D. Void band
37. What type of emission is frequency modulation?
A. F3E
B. G3E
C. A3E
45. Modulation of an RF amplifier carrier results in
A. Multiple channels
B. Smaller antennas
53. When a carrier is modulated 100%, the total power
C. Directional propagation
increases by what percentage over that of the carrier alone?
D. All of the above
46. A process which occurs in the transmitter
A. 25 %
B. 50 %
A. Mixing
C. 75 %
B. Modulation
D. 100 %
C. Heterodyning
54. When the amplitude of the modulating voltage is increased
D. Demodulation
for AM, the antenna current will
47. A process which occurs in the receiver
A. Increase
A. Beating
B. Decrease
B. Modulation
C. Remain constant
C. Mixing
D. Decrease exponentially
D. Demodulation
48. One part of the transmitter that protects the crystal
55. An increase in transmitter power from 25W to 30W will cause the antenna current to increase from 700mA to
oscillator from “pulling”.
A. 800 mA
A. Buffer amplifier
B. 750 mA
B. Modulator
C. 767 mA
C. Power amplifier
D. 840 mA
D. Antenna coupler
49. What aspect of the carrier is c hanged by modulation?
56. A second modulating tone having the same amplitude but a different frequency is added to the first at the input to the
A. Frequency
modulator. The modulation index will be increased by a factor
B. Phase
of
C. Amplitude
A. sq. root of 3
D. Depends on the type of modulation
B. sq. root of 2
50. The amplitude of a sine wave which is modulated by a
C. 2
musical program will
D. 3
A. Be complex
57. A 1000 kHz carrier is modulated by a 2500Hz tone. One
B. Contain fundamental frequencies
frequency component of the modulated signal is
C. Contain harmonic frequencies
A. 1200 Hz
D. All of the above
B. 5000 Hz
51. What will be the result of the gain level being too high for
C. 1002.5 kHz
signals entering the modulator?
D. 2500 Hz
A. Receiver noise
58. A 1200 kHz carrier is amplitude-modulated by two tones of
B. Excessive volume of receiver output
500 Hz and 700 Hz. W hich one is a frequency component of
C. Oscillator disturbances
the modulated wave?
D. Distortion and splatter
A. 1195 kHz
52. Amplitude modulation causes the amount of transmitter
B. 1199.3 kHz
power to
C. 1199.7 kHz
D. 1205 kHz
A. Increase
B. Decrease
59. Identify a modulation method, or methods in use for a
C. Remain the same
common-emitter configuration
D. Double
A. Base modulation
B. Emitter modulation
67. In FM, the change in carrier frequency is proportional to
C. Collector modulation
what attribute of the modulating signal?
D. Both A and C
A. Angle
60. The RF signal injected into a balanced modulator is 10MHz
B. Frequency
and the modulating frequency is 1 kHz. W hich frequency, or
C. Amplitude
frequencies, will not appear in the output?
D. Tone
A. 9.999 MHz
68. A louder sound, when generating the modulating waveform
B. 10 MHz
for FM, will cause a greater
C. 10.0001 MHz
A. Carrier amplitude
D. Both A and B
B. Angle amplitude
61. Unwanted sidebands in SSB equipment can be
C. Distortion at the receiver
suppressed by one or more of the following methods.
D. Frequency deviation
A. Phasing method
69. If a positive change in modulation signal level of 200 mW
B. Filter method
will cause a positive frequency deviation of 10 kHz, what will
C. Decoder method
be the frequency deviation for a negative change of 10 mV in
D. Both A and B
the level of the modulating signals?
62. Envelope detection is concerned with the process of
A. 0
A. Mixing
B. -5 kHz
B. Heterodyning
C. +5 kHz
C. Modulation
D. +0 kHz
D. Rectification
63. Diagonal clipping in envelope detection will result in
70. A particular 15 kHz modulation tone results in a peak frequency deviation of 75 kHz. What is the modulation index?
A. Distortion
A. 5
B. Phase reversal
B. 15
C. Reduced sensitivity
C. 75
D. Amplitude damage
D. 3
64. Product detection requires the process of
71. A 15 kHz sine wave frequency modulates an 88 MHz
A. Rectification
B. Heterodyning
A. 87.970 MHz
C. Decoding
B. 87.985 MHz
D. Phase shifting
C. 88.015 MHz
D. All of these
65. A sine wave which is coherent with carrier has identical
carrier. A sideband frequency will be found at
A. Amplitude
72. A device whose capacitance is deliberately made to be a
B. Frequency
function of the applied voltage
C. Phase angle
A. Varactor diode
D. Both B and C
B. UJT
66. Frequency modulation and phase modulation are
C. SAW
collectively referred to as
D. Variable capacitor
A. Stereo
73. A reactance modulator is one method of obtaining
B. Angle modulation
A. Indirect FM
C. High fidelity modulation
B. Direct FM
D. FCC modulation
C. Demodulation
D. Low frequency filtering
81. A quadrature detector requires that
74. A device, now available in IC form, is useful for direct FM
A. Four gates bee provided
and as one element in the phse-locked loop.
B. The inputs are coherent
A. AFC
C. The inputs are incoherent
B. AGC
D. The inputs are identical
C. VCO
D. LPF
82. In a phase-locked loop, the VCO is the abbreviation for
A. Variable coherent output
75. _____ is a frequency change process , whereby the phase
B. VHF communication oscillator
deviation and frequency deviation are multiplied by some fixed
C. Voltage-controlled oscillator
constant.
D. Vien-count oscillator (neutralized)
A. Translation
83. Identify an advantage, or advantages of a properly
B. Multiplication
designed FM system.
C. Division
A. Relative immunity to atmospheric noise (lightning)
D. Addition
B. Reduced bandwidth required
76. A circuit that has the function of demodulating the
C. No noise of any kind
frequency-modulated signal.
D. The noise figure is inversely proportional to the
A. AFC
B. Envelope detector
C. Decoder
A. LSB and USB
D. Foster-Seeley discriminator
B. LSB
C. USB
D. Carrier
77. The ratio detector is superior to the slope detector because
modulation index 84. The output of a balanced modulator
A. It is less sensitive to phase modulation
B. It is less sensitive to noise spikes
85. If the modulation index of an AM wave is changed from 0 to
C. It is less sensitive to interference causing AM
1, the transmitted power is
D. Both B and C
78. One implementation of a pulse averaging discriminator is
A. Unchanged
B. Halved
A. A free-running multivibrator
C. Doubled
B. A crystal-controlled oscillator
D. Increased by 50%
C. A quartz crystal filter
86. Which of the following is not a baseband signal of
D. A triggered multivibrator
modulation?
79. A 10% increase in the frequency of a constant-width pulse
A. Audio signal
train should cause what change in its average value?
B. Video signal
A. –10 %
C. RF carrier
B. –1 %
D. Binary coded pulses
C. +1 %
87. If the unmodulated level peak carrier amplitude is doubled
D. +10 %
in an AM signal, the perfect modulation is ________.
80. Two different signals can be coherent if they
A. 20
A. Have the same amplitude
B. 50
B. Are both sine waves of different frequencies
C. 100
C. Originate in the same physical equipment
D. 200
simultaneously
88. Balanced modulator circuit when inserted in the equivalent
D. Have the same frequency
suppresses the ___________
A. Carrier
B. Twice the srcinal index
B. Upper sideband
C. Four times the srcinal index
C. Lower sideband
D. One-half the srcinal index
D. Baseband signal
89. The carrier of a 100% modulated AM wave is suppressed, the percentage power saving is __.
96. An AM transmitter is rated 1000 W at 100% modulation. How much power required for the carrier?
A. 1000 W
A. 100 %
B. 666.6 W
B. 50 %
C. 333.3 W
C. 83 %
D. 866.6 W
D. 66.66 %
97. Standard way of designating AM
90. If the modulation index if an AM wave is doubled, the
A. A3E
antenna current is also doubled, the AM system being used is
B. B3E
A. H3E
C. AHE
B. J3E
D. C3F
C. C3F
98. _____ is the circuit used to detect frequency modulated
D. A3E
signal.
91. 100% modulation in AM means a corresponding increase
A. Discriminator
in total power by _______.
B. Modulator
A. 100 %
C. Modem
B. 50 %
D. Detector
C. 75 %
99. _____ is an information signal that is sent directly without
D. 25 %
modulating any carrier.
92. A single-tone amplitude modulated wave has _______.
A. C-band
A. 2 components
B. Q-band
B. 3 components
C. Baseband
C. 4 components
D. Broadband
D. 2n + 1 components
93. A carrier signal has ________.
100. Both frequency and phase modulation utilize ______ modulation.
A. Constant peak amplitude
A. Digital
B. Frequency range of 20 – 20,000 Hz
B. Phase
C. A varying amplitude
C. Amplitude
D. The information
D. Angle
94. The modulating system is _________ if the modulating
01. It is the width of frequencies within the spectrum occupied
frequency is doubled, the modulation index is halved, and the
by a signal and used by the signal for conveying information.
modulating voltage remains constant.
A. Band
A. Amplitude modulation
B. Bandwidth
B. Phase modulation
C. Electronic spectrum
C. Frequency modulation
D. Frequency band
D. Pulse modulation
102. Which transmit only one sideband?
95. What is the modulation index of an FM signal if its
A. H3E
modulating frequency is doubled?
B. C3F
C. A3E
A. No effect
D. B8E
103. ______ is kind of modulation in which the modulated wave is always present.
C. Low-Q tank circuit
D. IF strip
110. If the frequency of each component in a signal spectrum
A. Carrier modulation
B. Continuous modulation
A. Modulation
C. Log-periodic modulation
B. Frequency translation
D. Square-wave modulation
C. Up conversion
D. Both B and C
104. A type of modulation in which no signal is present between pulses.
is increased by the same fixed a mount, this known as
111. A particular amplifier is designed to be a frequency
A. Pulse modulation
doubler. If the input signal frequency is 15.4 MHz, a circ uit in
B. FSK
the output will be tuned to
C. QAM
A. 7.7 MHz
D. PAM
B. 15.4 MHz
105. What describes the amount of amplitude change pre sent
C. 30.8 MHz
in an AM waveform?
D. 61.6 MHz
A. Percent modulation
112. A sine wave of 293 MHz is phase-modulated to achieve a
B. Modulation constant
maximum phase deviation of 0.2 radian. After passing through
C. Envelope of modulation
a frequency tripler, the maximum phase deviation will be
D. Coefficient of modulation
A. 0.2 radian
106. _______ is a form of amplitude distortion introduced when
B. 0.3 radian
the positive and negative alternations in the AM modulated
C. 0.4 radian
signals are not equal.
D. 0.6 radian
A. Envelope distortion
B. Spurious emission
A. Active
C. Carrier shift
B. Passive
D. Johnson noise
C. Linear
D. Nonlinear
107. What is the advantage of phase modulation over direct FM frequency modulation?
113. Any device to be used as a frequency multiplier must be
114. A particular amplifier circuit used for frequency doubling.
A. Multipliers can be used
A. Push-push
B. The deviation is smaller
B. Push-pull
C. Simplicity and practicality
C. Pull-push
D. The oscillator is crystal-controlled
D. Pull-pull
108. If the spectrum is shifted in frequency with no other changes, this is known as
115. Frequency division is useful in the implementation of a
A. AM demodulator
A. Frequency multiplication
B. Frequency synthesizer
B. Sideband movement
C. AGC circuit
C. Baseband reorientation
D. FM demodulator
D. Frequency translation
109. A device which is capable of causing frequency translation
116. Frequency division by 12 will require how many flip-flops in the counter?
A. 3
A. High-Q tank circuit
B. 4
B. Balanced modulator
C. 6
D. 12
117. Identify an electronic device, not specifically designed for
124. A receiver in which all RF amplifier stages require manual tuning to the desired RF is called
the purpose, which can be used as a phase detector.
A. Superheterodyne
A. Wien bridge
B. Autodyne
B. Colpitts oscillator
C. TRF
C. Balanced modulator
D. AFC
D. Butterworth filter
118. A particular frequency synthesizer contains only a s ingle
125. Why is it often necessary to precede the demodulator by amplifier stages in a receiver?
crystal. What words describe this synthesizer?
A. To improve fidelity
A. Crystal modulated
B. To reduce receiver noise
B. Inexact
C. To eliminate image response
C. Indirect
D. Weak antenna signals
D. Deficient
126. A serious disadvantage of the TRF receiver.
119. A recognizable feature of a CW transmitter is
A. Bandwidth variations over the tuning range
A. Keyed transmitter
B. The weight and cost
B. Power amplification
C. The requirements for a closely regulated power
C. Frequency generation
D. All of these
120. The term “pulling” refers to
supply
D. The requirements for a half-wave antenna
127. Identify which is not a part of a s uperheterodyne receiver.
A. The change of the crystal oscillator frequency by
A. Local oscillator
loading
B. Modulator
B. One half-cycle operation of a push-pull amplifier
C. IF amplifier
C. Loading on the transmitter caused by
D. Demodulator
the antenna connection
128. Which major element will not be found in e very
D. Reduction of the power supply terminal voltage as
superheterodyne receiver?
A. R–F amplifier
121. When frequency modulation is achieved by initial
B. Mixer
phase modulation, this is called
C. Local oscillator
A. Angular modulation
D. IF amplifier
B. Direct FM
129. Which major element of a superheterodyne receiver must
C. Indirect FM
be nonlinear?
D. Indirect synthesis
the transmitter is keyed.
122. A disadvantage of direct FM is the need for
A. R-F amplifier
B. Mixer
A. AGC
C. Local oscillator
B. AFC
D. IF amplifier
C. A frequency synthesizer
130. The change of the modulated carrier frequency from the
D. Phase modulation
srcinal RF to the IF of the superheterodyne receiver is known
123. Direct FM can be achieved by
as
A. A reactance tube modulator
A. Frequency multiplication
B. A varactor diode
B. Frequency allocation
C. And AGC circuit
C. Frequency substitution
D. Both A and B
D. Frequency translation
131. The key to achieving receiver s ensitivity is the reduction
C. The image frequency
of
D. The image rejection ratio
A. Image response
B. Mixer harmonic products
A. Teflon
C. Spurious frequency response
B. Computer nylon
D. Internal noise
C. Powdered iron
D. Laminated steel
132. Which of the following receiver design objectives is not impossible?
138. The core of an IF transformer usually c ontains
139. Shape factor is a measure of
A. Elimination of galactic noise
A. Bandwidth
B. Elimination of atmospheric noise
B. Skirt steepness
C. Elimination of man-made noise
C. Coupling coefficient
D. Reduction of receiver internal noise
D. Critical coupling
133. In comparing the S/N ratio for the input to the receiver
140. _______ is the function which tends to maintain the sound
with the S/N ratio for the output, the latter is
volume level of a voice receiver nearly constant for a large
A. Smaller
B. The same
A. Squelch
C. Greater
B. Muting
D. Infinite
C. AGC
D. AFC
134. The characteristic of a receiver that specifies the self generated noise.
signal strength range.
141. The function which tends to silence the receiver in the
A. Noise immunity
B. Noise factor
A. Squelch
C. Noise figure
B. Muting
D. Noise margin
C. AGC
D. AFC
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?
absence of transmitted carrier.
142. What device is incorporated in a communications receiver
A. 77.3 MHz
B. 88.0 MHz
A. Front-end processor
C. 109.4 MHz
B. Squelch circuit
D. 120.1 MHz
C. AGC
D. Noise blanker
136. A source of RF interference exists at 109.9 MHz. For
to reduce impulse noise?
which frequency in the FM broadcast band will this be the
143. What type of signal in which a receiver selectivity of 2.4
image frequency?
kHz in the I-F circuitry is optimum?
A. 21.4 MHz
A. FM voice
B. 88.5 MHz
B. Double-sideband AM voice
C. 99.2 MHz
C. FSK data
D. 110.7 MHz
D. SBB voice
137. The ratio of the superheterodyne receiver response at the
144. If the input to a detector stage is an amplitude-modulated
desired carrier frequency to that at the image frequency is
(A3E) IF signal then the output from the stage is
called
A. A lower frequency carrier
A. The sensitivity
B. The audio voice information
B. The selectivity
C. A Morse-code signal
D. The upper or lower set of sidebands
145. In a capacitive type, reactance-tube modulator connected
151. An effect in which, the modulation of an unwanted signal is transferred to the desired carrier.
across an oscillator tuned circuit, a more negative voltage on
A. Crossmodulation
the grid of the reactance tube will cause
B. Intermodulation
A. An increase of the oscillator frequency
C. Modulation mixing
B. An decrease of oscillator frequency
D. Image-channel interference
C. An increase of the reactance-tube c apacitance
152. Leads should be kept as s hort as possible in radio circuit
D. An increase of the reactance tube ac plate current
so that
146. The limiting condition for sensitivity in a communications
A. Skin effect is reduced
receiver is
B. There is less hysteresis e ffect
A. The noise floor of the receiver
C. There is less dielectric loss
B. Power supply output ripple
D. Stray coupling is minimized
C. The two-tone intermodulation distortion
153. The number of voice transmissions that can be packed
D. The input impedance to the detector
into a given frequency band for amplitude-compandored
147. When a communications receiver is tuned to a strong
single-sideband systems over conventional FM-phone
signal, the AGC bias is measured and found to be zero. The
systems.
fault cannot be caused by a/an
A. 2
A. Defective IF stage
B. 18
B. Defective local oscillator
C. 16
C. Defective RF stage
D. 4
D. Open circuit in the AGC’s filter capacitor
148. The term used to refer to the condition where the signals
154. Neutralization of an RF amplifier stage can be necessary in order to
from a very strong s tation are superimposed on other signals
A. Increase the amplifier’s gain
being received
B. Prevent the generation of spurious oscillations
A. Cross-modulation interference
C. Reduce the amplifier’s gain
B. Intermodulation interference
D. Reduce the level of the output harmonics
C. Receiver quieting
155. The ability of a communications receiver to perform well in
D. Capture effect
the presence of strong signals outside the band of interest is
149. The limiter stage of an FM receiver
indicated by what parameter?
A. Behaves as a low-pass filter
A. Blocking dynamic range
B. Limits the amplitude of the IF signal to the required
B. Noise figure
level
C. Signal-to-noise ratio
C. Behaves as a high-pass filter
D. Audio output
D. Behaves as a bandstop filter
156. Stages that are common to both AM and FM receivers
150. Motorboating (low-frequency oscillations) in an amplifier
A. Tuner, local oscillator, detector, AF amplifier
can be stopped by
B. RF amplifier, mixer, IF amplifier, AF amplifier
C. Local oscillator, RF amplifier, frequency
A. Grounding the screen grid
B. Connecting a capacitor between the B+ and lead ground
discriminator, detector
D. Tuner, IF amplifier, detector, AF amp
C. By passing the screen grid resistor with a 0.1 µF
157. Occurs during CW reception if too narrow a filter
capacitor
bandwidth is used in the IF stage of a receiver
D. Grounding the plate
A. Filter ringing
B. Undesired signals will reach the audio s tage
A. In the detector
C. Output-offset overshoot
B. In the atmosphere
D. Cross-modulation distortion
C. In the ionosphere
D. In the receiver front end
158. What stage mainly determines a communication receiver’s sensitivity?
165. Cross-modulation in a receiver can be reduced by
A. IF amplifier
A. Installing a filter at the receiver
B. Mixer stage
B. Using a filter at the receiver
C. Detector stage
C. Increasing the receiver’s RF gain while decreasing
D. RF amplifier
159. What is the main advantage of FM over A M?
the AF
D. Adjusting the pass-band tuning
A. Better signal-to-noise-ratio
B. Narrower bandwidth
A. F3E
C. Greater propagation range
B. G3E
D. Total freedom from adjacent-channel interference
C. J3E
D. H3E
160. An amplitude modulation created in an amplifier before the final RF stage.
166. What is the emission designation for FM telephony?
167. What is the cause of receiver de sensitizing?
A. Low-level modulation
B. High-level modulation
C. Direct modulation
B. Audio gain adjusted too low
D. Indirect modulation
C. Squelch gain adjusted too high
D. Squelch gain adjusted too low
161. Receiver desensitizing can be reduced by
A. The presence of a strong signal on a nearby frequency
A. Increasing the transmitter audio gain
168. In a phase-modulated signal (indirect FM), the frequency
B. Decreasing the receiver squelch gain
deviation is directly proportional to the
C. Increasing the receiver bandwidth
A. Carrier amplitude only
D. Ensuring good RF shielding between the
B. Amplitude of the modulating tone and frequency of
transmitter
the carrier
162. In a narrow-band FM system, the deviation ratio is
C. Carrier frequency only
commonly one and the highest audio frequency is generally
D. Modulating signal amplitude only
limited to
169. An RF stage precedes the mixer stage in a
A. 300 Hz
superheterodyne receiver. One advantage of including this RF
B. 10,000 Hz
stage is
C. 3,000 Hz
A. Better selectivity
D. 7,500 Hz
B. Better rejection ratio
163. A type of emission is produced when an amplitude
C. Greater sensitivity
modulated transmitter is modulated by a facsimile signal
D. Improved signal-to-noise-ratio
A. A3F
B. F3F
A. Dynamic range and third-order intercept
C. A3C
B. Cost and availability
D. F3C
C. Bandwidth and noise figure
D. Intermodulation distortion and dynamic range
164. Where is the noise generated which primarily determines
170. Two factors that determine the sensitivity of a receiver.
the signal to noise ratio in a VHF (150 MHz) marine band
171. What is an undesirable effect of using too-wide a filter
receiver?
bandwidth in the IF section of a receiver?
A. Undesired signals will reach the audio stage
A. Avoid the requirement of neutralizing the stage
B. Output-offset overshoot
B. Raise the input impedance
C. Thermal-noise distortion
C. Lower the output impedance
D. Filter ringing
D. Obtain maximum power output
172. A system containing a limiter stage, a disc riminator, and a
179. The AM detector performs two basic functions in the
de-emphasis circuit?
receiver.
A. Direct FM transmitter
A. Rectifies and filters
B. Indirect FM transmitter
B. Amplifiers and filters
C. Single sideband AM receiver
C. Buffer and amplifier
D. FM receiver
D. Buffer and detector
173. The limiter stage of an FM receiver
180. A varactor diode can be used in a/an
A. Prevents any amplitude modulation of the IF signal
A. Direct FM modulator circuit
B. Limits the amount of frequency deviation in the IF
B. AFC circuit in a direct FM transmitter
signal
C. Phase-modulator circuit
C. Limits the overall bandwidth of the IF stages
D. All of these
D. Corrects any deviation in carrier frequency
181. Receiver interference is not reduced by including a/an
174. High selectivity occurs when the degree of c oupling
A. Crystal filter
between a receiver’s RF stages is
B. Insulating enclosures around the receiver
A. Tight
C. Wave trap
B. Loose
D. RF stage
C. Critical
D. Adjusted for maximum power transfer
182. What is the emission C3F?
A. RTTY
175. A carrier is phase modulated by a test tone. If the
B. SSB
amplitude and the frequency of the tone are both doubled, the
C. Television
amount of the deviation is
D. Modulated CW
A. Doubled
183. What is the approximate dc input power to a class AB RF
B. Unchanged
power amplifier stage in an unmodulated carrier transmitter
C. Halved
when the PEP output is 500 W?
D. Multiplied by four
A. Approximately 1000 W
176. The degree of selectivity desirable in the IF circuitry of a
B. Approximately 800 W
single-sideband receiver.
C. Approximately 250 W
D. Approximately 600 W
A. 1 kHz
B. 2.4 kHz
184. Which of the following stages in an FM receiver is
C. 4.2 kHz
responsible for drastically reducing the effect of static noise
D. 4.8 kHz
during the reception of a signal
177. The component most apt to break down in the radio circuit
A. De-emphasis circuit
is the
B. Mixer stage
A. Crystal
C. Squelch circuit
B. Resistor
D. Limiter stage
C. Transformer
D. Diode
178. The base in an RF amplifier is grounded in order to
185. The letters “SSSC” stands for
A. Single sideband, single carrier
B. Suppressed sideband, single channel
C. Suppressed sideband, single carrier
B. Installing capacitive spark plugs
D. Single sideband, suppressed carrier
C. Installing resistors in series with the spark plugs
D. Installing two copper-braid ground strips
186. For many types of voices, what is the ratio of PEP-toaverage power during a modulation peak in a single-sideband phone signal?
A. Approximately 1.0 to 1
B. Approximately 25 to 1
C. Approximately 100 to 1
D. Approximately 2.5 to 1
187. In most mixers, the oscillator frequency is ______ than the carrier frequency of the input signal.
193. The carrier in an AM transmitter is the
A. Transmitter’s output signal when the modulation is present
B. Transmitter’s output signal when the modulation is zero
C. Output signal from the crystal oscillator
D. RMS value of the AM signal
194. What stage feeds the discriminator of an FM receiver?
A. Higher
A. Local oscillator
B. Lower
B. Mixer stage
C. The same
C. Final IF amplifier, which also acts as a limiter stage
D. 10 kHz above
D. Buffer
188. Features of a transmitter’s buffer stage include
195. In an FM receiver, the stage that has the IF signal is input
A. High stage
B. Harmonic generation
A. Limiter
C. Improvement in frequency stability of the oscillator
B. Audio amplifier
D. Low input impedance
C. IF amplifier
D. Discriminator
189. Type of emission produced when an amplitude modulated transmitter is modulated by a television signal
A. F3F
B. A3C
C. F3C
D. A3F
190. A network is
B. A power incidence network
C. An antenna matching network that is isolated from ground
191. How is G3E FM-phone signals produced? A. A network consisting modulator on the audio
A. All signals on a frequency are demodulated by an FM receiver
B. The loudest signal received is the only demodulated signal
C. All signals on a frequency are demodulated by an AM receiver
D. The weakest signal received is the only demodulated signal
197. A double-sideband phone signal can be generated by
D. A network consisting of one inductor and two capacitors
196. What is capture effect?
A. A network consisting entirely of four inductors or four capacitors
and the audio signal output.
A. Feeding a phase-modulated signal into a low-pass filter
B. Modulating the plate voltage of a class-C amplifier
C. Using a balanced modulator followed by a filter
D. Detuning a Hartley oscillator
amplifier
198. Pre-emphasis is used in FM transmitters to improve the
B. With a reactance modulator on the final amplifier
signal-to-noise ratio of
C. With a reactance modulator on the oscillator
A. High modulating frequencies
D. With a balanced modulator on the oscillator
B. Low modulating frequencies
C. All modulating frequencies
D. Frequencies carrier
192. A way of eliminating auto interference to radio reception
A. Installing resistive spark plugs
199. The result of cross-modulation is that
B. Bandwidth of emission and occupied bandwidth
A. The modulation of an unwanted signal is heard on
C. Operating bandwidth
the desired signal
D. All of these
B. A decrease in modulation level of transmitted
206. A class-C RF amplifier is collector amplitude modulated
signals
and its average dc level collector current does not change.
C. Of receiver quieting
This means
D. Of inverting sidebands in the final stage of the
A. A normal condition
amplifier
B. Excessive drive to the base
C. Insufficient drive to the base
D. Insufficient audio modulation
200. Which of the following contains de-emphasis circuit?
A. FM transmitter
B. FM receiver
207. What determines the percentage modulation of an FM
C. VHF transmitter
transmitter?
D. VHF receiver
201. What is emission F3F?
A. Amplitude of the carrier
B. Modulating frequency
A. AM
C. Carrier frequency
B. Facsimile
D. Amplitude of the modulating signal
C. Television
D. RTTY
208. Deviation ratio of an FM transmitter is the ratio of the
202. What type of emission is produced when a frequency modulated transmitter is modulated by a facsimile signal?
A. Maximum frequency swing to the highest modulating frequency
B. Operating frequency of the assigned frequency
A. F3C
C. Frequency swing to the modulating frequency
B. A3C
D. Highest modulating frequency to the minimum
C. F3F
D. A3F
203. Two AM transmitting antennas are close together. As a
frequency 209. The main purpose of the beat frequency oscillator (BFO) is to generate
result the two modulated signals are mixed in the final RF
A. A 1 kHz not for Morse reception
stage of both transmitters. What is the resultant effect on other
B. Aid in the reception of weak voic e-modulated
station?
signals
A. Harmonic interference
B. Intermodulation interference
C. Spurious interference
D. Crossmodulation interference
C. An output, whose frequency differs from the IF by 1 kHz
D. A signal, whose frequency is the same as intermediate frequency
204. The term used to refer to the reduction of receiver gain
210. Normally, a linear class BRF power amplifier operates
caused by the signal of a nearby station transmitter in the
with a bias approximately equal to
same frequency band?
A. Twice cut-off
A. Quieting
B. Ten times cut-off value
B. Cross-modulation interference
C. 50% of cut-off value
C. Squelch gain rollback
D. Projected cut-off
D. Desensitizing
205. What is the bandwidth occupied by the carrier, both sidebands and harmonics?
A. Authorized bandwidth
211. The purpose why an RF amplifier is operated under linear class-B conditions (as opposed to class-C) is to
A. Generate only even harmonics
B. Generate only odd harmonics
C. Increase the efficiency
A. Zero beat
D. Amplify of an AM signal
B. Under-modulation
212. The term used to refer to the condition where the signal
C. Zero-modulation
from a very strong s tation are superimposed on other signal
D. Over-modulation
being received.
219. What is the approximate bandwidth of an FM with a
A. Cross-modulation interference
modulation factor of 12.5 and a modulating frequency of 10
B. Intermodulation distortion
kHz?
C. Receiver quieting
A. 20 kHz
D. Capture effect
B. 270 kHz
213. _________ is the amplitude of the maximum negative
C. 250 kHz
excursion of a signal as viewed on an oscilloscope.
D. 45 kHz
A. Peak-to-peak voltage
B. Inverse peak positive voltage
A. Linear mixing
C. RMS voltage
B. Analog multiplication
D. Peak negative voltage
C. Signal summation
D. Multiplexing
214. The type of emission that suffer most from s elective fading.
220. Amplitude modulation is the same as
221. The negative half of the AM wave is supplied by a/an
A. CW and SSB
B. SSB and TV
A.
C. FM and double sideband AM
B. Transformer
D. SSTV and CW
C. Capacitor
D. Inductor
215. In an FM-phone signal, ________ is the ratio between the actual frequency deviation to the maximum frequency deviation.
_______ on a diode modulator.
222. One of the following can produce AM.
A. Having the carrier vary a resistance
A. FM compressibility
B. Having the modulating signal vary a capacitance
B. Modulating index
C. Varying the carrier frequency
C. Percentage of modulation
D. Varying the gain of an amplifier
D. Quieting index
223. Amplitude modulators that vary the carrier amplitude with
216. _______ is used to refer to the reception blockage of one
the modulating signal by passing it through an attenuator
FM-phone signal by another FM-phone signal.
network is the principle of
A. Capture effect
A. Rectification
B. Desensitization
B. Amplification
C. Cross-modulation interference
C. Variable resistance
D. Frequency discrimination
D. Absorption
217. A receiver selectivity of 10 kHz in the IF circuitry is
224. Which component is used to produce AM at very high
optimum for what type of signals?
frequencies?
A. SSB voice
A. Varactor diode
B. Facsimile
B. Thermistor
C. FM
C. Cavity resonator
D. Double-sideband AM
D. PIN diode
218. If the envelope of modulation is constant in amplitude this means
225. A collector modulator has a supply voltage of 48 V. What
B. Rectifier
is the peak-to-peak amplitude of the modulating signal for 100
C. Bridge
percent modulation?
D. Constant current source
A. 24 V
B. 48 V
A. LC networks
C. 96 V
B. Mechanical resonators
D. 120 V
C. Crystals
D. RC networks and op amps
226. What circuit recovers the srcinal modulating information from an AM signal?
233. The most commonly used filter in SSB generators uses
234. In the phasing method of SSB generation, one sideband
A. Modulator
B. Demodulator
A. Phase shifting
C. Mixer
B. Sharp selectivity
D. Crystal set
C. Carrier suppression
D. Phase inversion
227. What is the most commonly used amplitude demodulator?
is canceled out due to
A. Envelope detector
235. A balanced modulator used to demodulate a SSB signal
B. Balanced modulator
is call a/an
C. Mixer
A. Transponder
D. Crystal set
B. Product detector
228. What circuit generates the upper and lower sidebands
C. Converter
and suppresses the carrier?
D. Remodulator
A. Amplitude modulator
B. Diode detector
A. Summer
C. Class C amplifier
B. Multiplier
D. Balanced modulator
C. Divider
D. Mixer
229. _________ is a widely used balanced modulator.
236. Frequency translation is done with a circuit called a
A. Diode bridge circuit
B. Full-wave bridge rectifier
A. Rectification
C. Lattice modulator
B. AM
D. Balanced bridge modulator
C. Linear summing
D. Filtering
230. In a diode ring modulator, the diodes act like
237. Mixing for frequency conversion is the same as
A. Variable resistors
238. Which of the following is not a major advantage of FM
B. Switches
over AM?
C. Rectifiers
A. Greater efficiency
D. Variable capacitors
B. Noise immunity
C. Capture effect
D. Lower complexity and cost
231. The output of a balanced modulator is
A. AM
B. FM
C. SSB
A. Higher cost and complexity
D. DSB
B. Excessive use of spectrum space
232. The principal circuit in the popular 1496/1596 IC balanced
C. Noise susceptibility
modulator is a
D. Lower efficiency
A. Differential amplifier
239. The primary disadvantage of FM is its
240. Noise is primarily
A. High-frequency spikes
B. BFO
B. Lowe-frequency variations
C. Ratio detector
C. Random level shifts
D. All of these
D. Random frequency variations
241. The receiver circuit that rids FM of noise is the
249. Which of the following is the most widely used amplitude modulator
A. Modulator
A. Diode detector
B. Demodulator
B. PLL circuit
C. Limiter
C. VCO
D. Low-pass filter
D. All of these
242. The AM signals generated at a low level may only be
250. Which of the following is the most widely used balanced
amplified by what type of amplifier?
modulator
A. Class A
A. Full-wave bridge circuit
B. Class B
B. Balanced bridge modulator
C. Class C
C. Lattice modulator
D. All of the above
D. None of these
243. SSB means
251. A method that applied the modulated wave to the vertical
A. Single sideband with suppressed carrier
deflection circuit of the oscilloscope and the modulating signal
B. Single sideband with carrier
to the horizontal deflection circuit.
C. Double sideband with no carrier
a. Trapezoidal method
D. Single sideband with reduced carrier
b. Circular method
c. Square method
d. Any method
244. A circuit used to select the desired output from a mixer
A. Transformer
B. Resonant circuit
252. The heart of all methods of single-s ideband modulation
C. Filter
and demodulation
D. Phase-shift circuit
245. What is the output of a balanced modulator?
a. Modulator
b. Balanced modulator
A. AM
c. Modulation
B. DSB
d. demodulation
C. SSB
253. If the frequency and phase are parameters of carrier
D. ISB
angle, which is a function of time, the general term
246. The acronym SSSC refer to
___________-cover both.
A. Suppressed sideband, single carrier
a. Amplitude modulation
B. Suppressed sideband, suppressed carrier
b. Frequency modulation
C. Single sideband, suppressed carrier
c. Phase modulation
D. Single sideband, single carrier
d. Angle modulation
247. Which process occurs in the receiver?
254. In FM radio communication system, narrow-band (NBFM)
A. Demodulation
B. Reception
is used rather than wideband (WBFM), because it,
a. Improves signal to noise ration
C. Modulation
b. Reduces interchannel interference
D. Recreation
c. Provides maximum coverage for a given amount of
248. What is usually used to demodulate SSB or CW signal?
A. PLL
power
d. All of the above
255. Radio transmitter basically consists of two principal parts,
c. TV
one reproducing a carrier frequency and one for __________.
d. None of these
a. IF Frequency
262. Recovers the modulating voltage from the frequency
b. RF Frequency
modulation by utilizing the phase angle shift between primary
c. Modulating Frequency
and secondary voltages of tuned oscillators.
d. Power
a. Direct method
256. Is a measure of its ability to maintain as nearly a fixed
b. Indirect method
frequency as possible over as long as time interval as possible.
c. Foster-Seeley discriminator
d. Slope detector
a. Receiver Noise Factor
b. Selectivity
263. Is used in FM receivers to “lock onto” the received signal
c. Sensitivity
and stabilized receptions.
d. Frequency stability
a. Automatic Gain Control
257. Is the effect of two-transmitter when they are in c lose
b. Automatic Frequency Control
proximity. This results into the sum and difference frequencies
c. Muscle Control
of two carriers.
d. Automatic Frequency Gain Control
a. Intermodulation effect
264. Are amplifier circuits that are used to eliminate amplitude
b. Intermodulation interference
modulation and amplitude-modulated noise from received FM
c. Intermodulation product
Signals before detection.
d. intermodulation
a. Demodulators
258. _________ is a continuous frequency capable of being
b. Diode detector
modulated or impressed with a second information carrying
c. Amplitude limiters
signal.
d. None of these
a. Carrier frequency
265. If the total sideband power is 12.5% of the total radiated
b. Center frequency
power, find the modulation index.
c. IF frequency
a. 50 percent
d. RF frequency
b. 53.4 percent
259. The varactor diode used in FM may be represented by the
c. 26.2 percent
approximate equivalent circuit of the _____ in series with a
d. 32.3 percent
________.
266. Carriers are spaced at 20 kHz, beginning at 100 kHz.
a. Diode, capacitor
Each carrier is modulated by a signal with a 5 kHz bandwidth.
b. Diode, resistor
Is there interference from the sideband?
c. Capacitor, resistor
a. Yes
d. Any of these
b. No
c. Maybe
d. Secret
260. The name varactor comes from variable _________.
a. Resistor
b. Capacitor
267. For an unmodulated carrier of 150 V and a modulated
c. Diode
peak value of 230 V. What is the modulation index
d. reactor
a. 0.35
261. 75 microseconds pre-emphasis time is used in
b. 0.533
__________.
c. 0.652
d. 0.42
a. FM
b. AM
268. New frequencies outside the regular AM spectrum are
a. Monophonic
called ___________.
b. Stereophonic
a. Distortion
c. Stereonic
b. Interference
d. SCA
c. Splatter
275. It make use of the shape of IF filter frequency response
d. Harmonic
roll-off versus frequency.
269. A DSB-SC has a total power of 350 watts with 100%
a. Foster Seeley
modulation suppresses 50% of the carrier, and the suppressed
b. Slope detector
carrier power goes to the sidebands. How much power is in the
c. Diode detector
sidebands?
d. Quadrature detector
a. 116.67 W
276. In AM, modulation index is a number lying between ____
b. 233.33 W
and 1.
c. 175 W
a. 2
d. 350 W
b. 5
270. A DSB-SC system must suppress the carrier by 30 dB
c. 0
from its srcinal value of 30 W. What value must the carrier be
d. 3
reduced?
277. This form of modulation is also known as independent
a. 30000 W
b. 0.03 W
a. A3E
c. 300 W
b. R3E
d. 0.003 W
c. H3E
d. B8E
271. ___________, which further amplifies the signal and has
sideband emission.
the bandwidth and passband shaping appropriate for the
278. An attenuated carrier is reinserted into the SSB signal to
received signal.
facilitate receiver tuning and demodulation.
a. RF stage
a. A3E
b. Mixer and local oscillator stage
b. R3E
c. IF stage
c. H3E
d. AF stage
d. B8E
272. In FM, a bandwidth estimate 98 percent level of Bessel functions
279. Standard AM used for broadcasting
a. A3E
a. Approximate bandwidth
b. R3E
b. Narrow-band Bandwidth
c. H3E
c. Carson’s rule
d. B8E
d. Wideband bandwidth
273. The complete series of stages for reproducing the FM signal with the desired carrier and deviation is the _______.
280. Single sideband, suppressed carrier in which the carrie r is suppressed by at least 45 dB in the transmitter.
a. A3E
a. Modulator
b. R3E
b. Exciter
c. H3E
c. IF stage
d. B8E
d. RF stage
281. The shift in the carrier frequency from the resting point
274. Is the ability of FM system to provide low-noise, high
compared to the amplitude of the modulating signal is called
fidelity music background/broadcast..
_______.
a. Index
b. Deviation ratio
288. If the input resistance of the base station of AM broadcast
c. Carrier frequency
produced 20 kW carrier power, at what modulation index
d. Deviation frequency
should the antenna rise at 108.63 A?
d. 4 kW
282. In FM, the amplitude of the modulated frequency wave
a. 20%
remains ___________ at all times.
b. 50%
a. Varying
c. 60%
b. Dependent
d. 80%
c. Constant
289. ________ used a phase detector to compare the phase
d. variable
and frequency of the received signal to the VCO output.
283. An AM has a maximum span of 30 V, what is the required
a. PIL
minimum span to attain 100% modulation?
b. PAL
a. 30 V
c. PLL
b. 20 V
d. PLI
c. 0 V
290. A filter with a roll-off of 6 dB/kHz is used as a s lope
d. None of these
detector. The input signal varies with +3 kHz deviation from
284. DZMM having a carrier frequency of 630 kHz is
center carrier frequency. How many dB down is the output at
modulated by 2.6 kHz audio signal having an amplitude of 37.5
full deviation?
V. What is the amplitude voltage of 630 kHz carrier frequency
a. 9 dB
at 0.35 modulation index?
b. -18 dB
a. 57.6 V
c. 18 dB
b. 107.14 V
d. -9 dB
c. 206.5 V
291. A receiver limiter requires a 20 mV signal for quieting
d. 86.2 V
operation. The voltage gain between the RF input and the
285. If the sideband power is 50% of the carrier power, what is
limiter is 57.7 dB, what is the input at the antenna terminal
the modulation index?
assuming equal resistance?
a. 50%
a. 75.6 mV
b. 75%
b. 26.67 uV
c. 90%
c. 52.3 uV
d. 100%
d. 49.6 uV
286. If the increase power is 180 watts at 1 kW unmodulated
292. A 1-MHz carrier is modulated with a resulting 100 Hz
output power the modulation index is _________.
deviation. It undergoes x36 multiplication, followed by mixing
a. 75%
with a 34.5 MHz signal and re-multiplication by 72. What is the
b. 60%
final carrier and deviations?
c. 50%
a. 5076 MHz, ± 2592 MHz
d. 25%
b. 2592 MHz, ± 259.2 kHz
287. In AM, if the unmodulated power carrier is 10 kW, and the
c. 2592MHz, ± 5076 MHz
total power is 15 kW, what is the upper sideband power at
d. 259.2 MHz, ± 108 kHz
100% modulation index?
293. For standard commercial broadcast FM, the deviation
a. 25 kW
b. 2 kW
ratio is ________.
a. 15
c. 2.5 kW
b. 75
c. 5
300. Undesired signal on the other side of the local oscillator
d. 10
output will have the same difference frequency and pass into
294. A system has 150 kHz of bandwidth available for 10 kHz
the IF amplifier.
modulation signal. What is the approximate deviation to be
a. Carrier frequency
used?
b. Sum frequency
a. 35 kHz
c. Difference frequency
b. 65 kHz
d. Image frequency
c. 25 kHz
301. One of the following refers to an output of a balanced
d. 15 kHz
modulator
295. An FM has a deviation of 100 kHz and a modulating
a. SSB
frequency of 15 kHz, what happen to m if the deviation triples?
b. ISB
a. 6.66
c. AM
b. 2.22
d. DSB
c. 4.12
302. Which of the following components is used to produce AM
d. 0.20
at very high frequencies?
296. A receiver for a signal at 100 MHz uses a 10.7 MHz IF
a. Cavity resonator
and low tracking. What is the image frequency?
b. PIN diode
a. 89.3 MHz
c. Varactor
b. 78.6 MHz
d. Thermistor
c. 52.5 MHz
303. A third symbol emission which re present data
d. 35.2 MHz
transmission including telemetry, and telecommand
297. What is the change in resonant frequency of the actual
a. B
varactor capacitance value differs by -5% (0.05) of the nominal
b. D
value?
c. C
d. N
a. 2.06
b. 3.02
c. 1.03
a. None of these
d. 5.06
b. Sidebands
298. An oscillator resonate at 1 MHz with a nominal 100 pF
c. Both the sidebands and the carrier
capacitor and 0.25 mH inductor, what s the resonant frequency
d. Carrier
of the actual capacitor value is +20% of the nominal value?
304. In an AM wave, useful power is carried by
305. Determine the modulation index of an standard FM
a. 1.006 MHz
broadcast having a hypothetical maximum carrier frequency
b. 0.9188 MHz
deviation of ±12 kHz and a maximum modulating frequency pf
c. 3.625 MHz
4kHz.
d. 2.00123 MHz
299. “Front end” is also called _________.
a. 9
b. 6
a. IF stage
c. 3
b. AF stage
d. 4
c. RF stage
306. The process by which the intelligence signals normally at
d. None of these
lower frequency are removed from the transmission frequency after it is received in the receiver s tation.
a. Detection
b. Demodulation
c. Amplification
313. One of the following is a communications filter generally
d. Modulation
used in the transceiver of a s ingle sideband generator.
307. What is meant by the term modulation?
d. A
a. Lowpass filter
a. The squelching of a signal until a c ritical signal-to-
b. Crystal filter
noise ratio is reached
c. Bandpass filter
b. Carrier rejection through phase nulling
d. Mechanical filter
c. A linear amplification mode
314. What is the modulation index for an AM s ignal having
d. A mixing process whereby information is imposed
Vmax and Vmin of 2.6 and 0.29, respectively?
upon a carrier 308. What is a balanced modulator?
a. 0.799
b. 0.111
a. An FM modulator that produces balance de viation
c. 0.894
b. A modulator that produces a DSBSC signal
d. 0.639
c. A modulator that produces a SSBSC signal
315. What is the bandwidth of an AM signal modulated by a
d. A modulator that produces a full carrier signal
15-kHz intelligence signal?
309. What is a reactance modulator?
a. 7.5 kHz
a. A circuit that acts as a variable resistance or
b. 15 kHz
capacitance to produce FM signals
c. 30 kHz
b. A circuit that acts as a variable resistance or
d. 60 kHz
capacitance to produce AM signals
316. If a transmitter supplies 10 kW to the antenna when it is
c. A circuit that acts as a variable inductance or
unmodulated, determine the total radiated power when it is
capacitance to produce FM signals
modulated at 30%
d. A circuit that acts as a variable inductance or
a. 10.45 watts
capacitance to produce AM signals
b. 10750 watts
c. 11.5 kilowatts
d. 10450 watts
310. How can an SSB phone signal be generated?
a. By dividing product detector with a DSB signal
b. By using a reactance modulator followed by a
317. Which of the following waveform characteristics
mixer
determines the wavelength of a sine wave?
c. By using a loop modulator followed by a mixer
a. Phase
d. By using a balanced modulator followed by a filter
b. Amplitude
c. Period
d. Phase angle
311. How can a DSB phone signal be generated?
a. By feeding a phase modulated signal into a low pass filter
318. In the F3E signal, what is the term for the ratio between
b. By using a balanced modulator followed by a filter
the deviation of a frequency modulated signal and the
c. By detuning a Hartley oscillator
modulating frequency?
d. By modulating the plate voltage of a class C
a. FM compressibility
amplifier
b. Quieting index
312. First symbol in the designation of radio s ignals emission
c. Modulation index
which refers to use of an unmodulated carrier.
d. Percentage of modulation
a. J
319. Which frequency band is the standard AM ra dio
b. N
broadcast?
c. H
a. HF
b. UHF
326. What is the source of sidebands in frequency modulated
c. MF
voice?
d. VHF
a. A3F
320. The letter-designation B8E is a form of modulation also
b. A3J
known as
c. F3E
d. J3E
a. Pilot carrier system
b. Independent sideband emission
327. The third symbol in the designation of radio emission
c. Lincompex
under the ITU refers to
d. Vestigial sideband transmission
a. Type of modulation of the main carrier
321. What are the two general categories of methods for
b. Nature of signals
generating emission F3E?
c. Type of information to be transmitted
d. Nature of multiplexing
a. The only way to produce an emission F3E signal is with reactance modulator on the oscillator
328. An AM transmission of 3 kW is 100% modulated. If it is
b. The only way to produce an emission F3E signal is
transmitted as an SSB signal, what would be the total power
with a balanced modulator on the oscillator
transmitted?
c. The only way to produce an emission F3E signal is
a. 500 W
with a balanced modulator on the audio amplifier
b. 1000 W
d. The only way to produce an emission F3E signal is
c. 1500 W
with a reactance modulator on the final amplifier
d. 2000 W
322. 100% modulation in AM means a corresponding increase
329. This circuit has the function of demodulating the
in total power by ____.
frequency-modulated signal. It is a
a. 25%
a. Automatic gain control
b. 75%
b. Automatic frequency control
c. 100%
c. Envelope detector
d. 50%
d. Foster-Seeley discriminator
323. How does the SSB transmitter output power normally
330. Calculate the power in one sideband of an AM signal
expressed?
whose carrier power is 50 watts. The unmodulated current is 2
a. Average power
b. In terms of peak envelope power
a. 22 W
c. In terms of peak-to-peak power
b. 33 W
d. Peak power
c. 11 W
d. 44 W
324. Determine from the following the common use of DSB in broadcast and telecommunications
A while the modulated current is 2.4 A.
331. The method of generating FM used by broadcasting
a. Satellite communication
b. FM/TV stereo
a. Direct
c. Two-way communications
b. All of these
d. Telephone systems
c. Indirect
d. Insertion
325. What is the source of sidebands in frequency modulation?
a. Oscillator
b. Baseband frequency
c. Mixer
d. Carrier harmonics
station is
332. Deviation ratio of an FM transmitter is the ratio of the
a. Maximum frequency swing to the highest modulating frequency
b. Operating frequency of the assigned frequency
c. Frequency swing to the modulating frequency
is 85% modulated by a 3 MHz sine wave. Calculate the RMS
d. Highest modulating frequency to the minimum
voltage of the signal.
frequency
a. 825 W
333. An AM transmitter is modulated by two sine waves at 1.5
b. 262. 61 V
kHz and 2.5 kHz with modulations of 20 percent and 80
c. 1166.7 V
percent respectively. Calculate the effective modulation index.
d. 825 V
a. 0.7776
340. What will be the total sideband power of the AM
b. 0.6
transmitting station whose carrier power is 1200W and a
c. 0.8246
modulation of 95%?
d. 1.0
a. 270.75 W
334. A DSBSC system must suppress the carrier by 50 dB for
b. 900 watts
its srcinal value of 10 W. To what value must the carrier be
c. 1.8 kW
reduced?
d. 542 W
a. 1 milliwatt
341. Which among the following is capable of generating
b. 10 microwatts
frequency conversion?
c. 0.10 milliwatts
a. Balanced modulator
d. 0.01 microwatts
b. Low-Q LC Circuit
335. Which circuit in the AM transmitter does the frequency
c. Transmitter
translation?
d. Circulator
a. Synthesizer
b. Modulator
a. Envelope detector
c. Mixer
b. PLL
d. Booster
c. Mixer
d. Balanced modulator
336. A phase modulator has Kp= 2 rad/V. What RMS voltage of a sine wave would cause a peak phase deviation of 30 degrees?
342. The most commonly used AM demodulator
343. Which is a disadvantage of direct FM generation?
a. The need for an AFC c ircuit
a. 0.158 V
b. The need for an AGC circuit
b. 0.185 V
c. Two balanced modulators are used
c. 0.518 V
d. The use of Class A amplifier which is very
d. 0.815 V
337. In a phase-locked loop, VCO stands for
inefficient 344. Frequency division is useful in the implementation of a/an
a. Variable capacitor oscillator
a. AM demodulator
b. Varactor-capacitor oscillator
b. Frequency synthesizer
c. Voltage-controlled oscillator
c. AGC circuit
d. VHF control oscillator
d. FM demodulator
338. Diagonal clipping in envelope detection will result in
345. A particular synthesizer which contains only a s ingle
a. Distortion
b. Diagonal clipping
a. Direct
c. Phase reversal
b. Crystal-modulated
d. Amplitude damage
c. Indirect
d. Exact
339. An AM transmitter supplies a 10 kW of carrier power to a 50 ohm load. It operates at a carrier frequency of 1.2 MHz and
crystal is
346. Type of emission most affected by selective fading
a. FM and DSB AM
b. Approximately equal to X L
b. SSB and TV
c. Low, as compared to the c ircuit resistance
c. CCTV and CW
d. Approximately equal to X C
d. CW and SSB
347. Which major element will not be found in every superheterodyne receiver?
354. What are the three major oscillator circuits often used in radio equipment?
a. Taft, Pierce, and negative feedback
a. RF amplifier
b. Colpitts, Hartley, and Taft
b. IF amplifier
c. Taft, Hartley, and Pierce
c. LO
d. Colpitts, Hartley, and Pierce
d. Mixer
348. A system uses a deviation of 100 kHz and a modulating frequency of 15 kHz. What is the approximate bandwidth?
355. How is a positive feedback coupled to the input in a Hartley oscillator?
a. Through a neutralizing capacitor
a. 115 kHz
b. Through a capacitive divider
b. 230 kHz
c. Through a link coupling
c. 170 kHz
d. Through a tapped coil
d. 340 kHz
349. A quadrature detector requires that
356. How is the positive feedback coupled to the input in a Colpitts oscillator?
a. The inputs are coherent
a. Through a tapped coil
b. Four gates are provided
b. Trough link coupling
c. The inputs are in phase
c. Through a capacitive divider
d. The inputs are similar
d. Through a neutralizing capacitor
350. What is the power in one sideband of an AM signal whose
357. How is a positive feedback coupled to the input in a
carrier power is 300 W, with 80 percent modulation?
Pierce oscillator?
a. 396 W
a. Through a tapped coil
b. Zero
b. Trough link coupling
c. 48 W
c. Through a capacitive divider
d. 96 W
d. Through a neutralizing capacitor
351. Determine the resonant frequency of a series combination
358. Which of the three major oscillator circuits used in radio
of a 0.001 microfarad capacitor and a 2 – milihenry inductor.
equipment utilizes a quartz crystal?
a. 112.5 kHz
a. Negative feedback
b. 35.59 kHz
b. Hartley
c. 1125.4 MHz
c. Colpitts
d. 3.26 MHz
d. Pierce
352. Which of the following is not a typical part of every radio transmitter?
a. Carrier oscillator
b. Driver amplifier
c. Mixer
d. Final power amplifier
359. What is the piezoelectric effect?
of a voltage
a. Approximately equal to the circuit resistance
b. Mechanical deformation of a crystal by the application of a magnetic field
353. What is the approximate magnitude of the impedance of a parallel RLC circuit at resonance?
a. Mechanical vibration of a crystal by the application
c. The generation of electrical energy by the application of light
d. Reversed conduction states when pn-junction is exposed to light
360. What is the major advantage of a Pierce oscillator?
a. It is easy to neutralize
b. It doesn’t require an LC tank circuit
c. It can be tuned over a wide range
d. It has high output power
361. Which type of oscillator circuit is commonly used in a VFO?
c. The use of a capacitor in a power supply to filter rectified AC
d. The transmission of a radio signal to a distant station by several hops through the ionosphere
367. How can parasitic oscillations be eliminated from a power amplifier?
a. By tuning for maximum SWR
a. Pierce
b. By tuning for maximum power output
b. Colpitts
c. By neutralization
c. Hartley
d. By tuning the output
d. Negative feedback
362. Why is the Colpitts oscillator circuit commonly used in a VFO?
368. If the spectrum is shifted in frequency with no other changes, this is known as
a. Frequency multiplication
a. The frequency is a linear function of the load
b. Sideband movement
impedance
c. Baseband orientation
b. It can be used with or without crystal lock-in
d. Frequency translation
c. It is stable
369. A device which is capable of causing frequency
d. It has high output power
translation
363. How is the efficiency of a power amplifier determined?
a. High-Q tank circuit
a. Efficiency = (RF power out / dc power in) x 100%
b. Balanced modulator
b. Efficiency = (RF power in / RF power out) x 100%
c. Low-Q tank circuit
c. Efficiency = (RF power in / dc power in) x 100%
d. IF strip
d. Efficiency = (dc power in / RF power in) x 100%
364. For reasonably efficient operation of a transistor amplifier,
370. If the frequency of each component in a signal spectrum is increased by the same fixed amount, this is known as
what should be the load resistance be with 12 volts at the
a. Up conversion
collector and a 5 watts power output?
b. Demodulation
a. 100.3 ohms
c. Frequency translation
b. 14.4 ohms
d. Both a and c
c. 10.3 ohms
371. A particular amplifier is designed to be a frequency
d. 144 ohms
doubler. If the input signal frequency is 15.4 MHz, a circ uit in
365. What order of Q is required by a tank circuit sufficient to reduce harmonics to an acceptable level?
the output will be tuned to
a. 7.7 MHz
a. Approximately 120
b. 15.4 MHz
b. Approximately 12
c. 30.8 MHz
c. Approximately 1200
d. 61.6 MHz
d. Approximately 1.2
366. What is the flywheel effect?
372. Any device to be used as a frequency multiplier must be
a. Active
a. The continued motion of a radio wave through
b. Passive
space when the transmitter is turned off
c. Linear
b. The back and forth oscillation of electrons in a n LC
d. Nonlinear
circuit
373. A particular amplifier circuit used for frequency coupling is known as
a. Push-push
c. Loudness controller
b. Push-pull
d. All of the above
c. Pull-push
381. Class C amplifiers are not used in which type of
d. Pull-pull
transmitter?
374. Frequency division is useful in the implementation of a
a. AM
a. AM demodulation
b. SSB
b. Frequency synthesizer
c. CW
c. FM demodulator
d. FM
d. AGC circuit
375. Indirect frequency synthesizers will include
382. A circuit that isolates the carrier oscillator from load changes is called a
a. phase-locked loop
a. Final amplifier
b. voltage-controlled oscillators
b. Driver amplifier
c. multiple bank crystals
c. Linear amplifier
d. both A and B
d. Buffer amplifier
376. A particular frequency synthesizer contains only a s ingle
383. Bias for class c amplifier produced by an input RC
crystal. What words describe this synthesizer?
network is known as
a. Crystal modulated
a. Signal bias
b. Inexact
b. Self-bias
c. Indirect
c. Fixed external bias
d. Deficient
d. Threshold bias
377. A recognizable feature of a CW transmitter is
384. Collector current in a class C amplifier is
a. Keyed transmitter
a. Sine wave
b. Power amplification
b. Half-sine wave
c. Frequency generation
c. Pulse
d. All of the above
d. Square wave
378. The term “pulling” refers to
385. Neutralizing is the process of
a. The change of the crystal osc illator frequency by
a. Cancelling the effect of internal device capacitance
loading
b. Bypassing undesired alternating current
b. One-half cycle operation of a push-pull amplifier
c. Reducing gain
c. Loading on the transmitter caused by the antenna
d. Eliminating harmonics
connection
386. In an AM transmitter, a clipper circuit eliminates
d. Reduction of the power supply terminal voltage as
a. Harmonics
the transmitter is keyed
b. Splatter
379. An AM broadcast transmitter in the multi-kilowatt
c. Over-deviation
operating range will have what form of final amplifier?
d. Excessive gain
a. Solid-state devices
387. The final power amplifier in an FM transmitter usually
b. Vacuum tubes
operates class
c. Travelling wave tubes
a. A
d. Both a and b
b. B
c. C
d. D
380. In a broadcast station, the AGC is referred to as
a. Automatic gain control limiter
b. Compression amplifier
388. A transistor RF power amplifier can be tuned for
a. Minimum I C in the next stage
a doubler is 198 MHz, what frequency s hould the oscillator
b. Zero signal in the next stage
operate?
c. Minimum I C in the same stage
a. 11 MHz
d. Maximum I C in the same stage
b. 33 MHz
389. The purpose of a balanced modulator circuit is to
c. 22 MHz
eliminate the
d. 66 MHz
a. Carrier
395. A phase-locked loop has a VCO with a free running
b. Upper sideband
frequency of 14 MHz. As the frequency of the reference input
c. Lower sideband
is gradually raised from zero, the loop locks at 12 MHZ and
d. Baseband signal
comes out of lock again at 18 MHz. Calculate the lock range.
390. A frequency multiplier circuit
a. 4 MHz
a. Operates class A
b. 2 MHz
b. Is tuned to a harmonic of the input signal
c. 12 MHz
c. Needs parasitic oscillations
d. 8 MHz
d. Is usually pulse modulated
391. An IF transformer of a radio receiver operates at 456 kHz.
396. A crystal oscillator is accurate within 0.0005%. How f ar off frequency could its output be at 37 MHz?
The primary circuit has a Q of 50 and the secondary has a Q of
a. 135 Hz
40. Find the bandwidth using the optimum coupling factor.
b. 150 Hz
a. 10.192 kHz
c. 185 Hz
b. 15.288 kHz
d. 224 Hz
c. 152.88 kHz
397. A transmitter has a carrier power output of 10 W at an
d. 101.92 kHz
efficiency of 80%. How much power must be supplied by the
392. A varactor has a maximum capacitance of 80pF and is
modulating amplifier for 100% modulation?
used in a tuned circuit with a 100 microhenry inductor. Find the
a. 6.25 W
tuning voltage necessary for the circuit to resonate at twice its
b. 7.14 W
resonant frequency with no tuning voltage applied.
c. 12.5 W
d. 14.3 W
a. 5 V
b. 2.5 V
398. A transmitter operates from a 16 V supply, with a collector
c. 7.5 V
current of 2 A. The modulation transformer has a turns ratio of
d. 4.25 V
4:1. What is the load impedance seen by the audio amplifier?
393. A phase-locked loop has a VCO with a free-running
a. 96 ohms
frequency of 14 MHz. As the frequency of the reference input
b. 128 ohms
is gradually raised from zero, the loop locks at 12 MHz and
c. 6 ohms
comes out of lock again at 18 MHz. Calculate the capture
d. 8 ohms
range.
399. A collector-modulated class C amplifier has a carrier
a. 4 MHz
output power of 150 W and an efficiency of 80%. Calculate the
b. 2 MHz
transistor power dissipation with 100% modulation.
c. 12 MHz
a. 93. 75 W
d. 8 MHz
b. 120 W
394. If the frequency fed to the pre-amplifier of a basic
c. 64 W
transmitter with multipliers is composed of a pair of triplers and
d. 56. 25 W
400. An AM transmitter is required to produce 20 W of carrier
406. What is the term used to refer to the condition where the
power when operating from a 25 V supply. What is the required
signals from a very strong station are super imposed on the
load impedance as seen from the collector?
other signals being received?
a. 15.625 ohms
a. Intermodulation distortion
b. 22.5 ohms
b. Cross-modulation interference
c. 11.25 ohms
c. Receiver quieting
d. 31.25 ohms
d. Capture effect
401. What is receiver desensitizing?
407. How can cross-modulation in a receiver be reduced?
a. A burst of noise when the squelch is set to low
a. By installing a filter at the receiver
b. A burst of noise when the squelch is set to high
b. By using a better antenna
c. A reduction in receiver sensitivity because of a
c. By increasing the receiver’s RF gain while
strong signal on a nearby frequency
d. A reduction in receiver s ensitivity is turned down
402. What is the term used to refer to the reduction of receiver
decreasing the AF gain
d. By adjusting the passband tuning
408. What is the result of cross-modulation?
gain caused by the signals of a nearby station transmitting in
a. Decrease in modulation level of transmitted signals
the same frequency band?
b. Receiver quieting
c. The modulation of an unwanted signal is heard on
a. Desensitizing
b. Quieting
c. Cross-modulation interference
d. Squelch gain roll back
403. What is the term used to refer to a reduction in rec eiver
the desired signal
sensitivity caused by unwanted high-level adjacent channel signals? a. Intermodulation distortion
b. Quieting
c. Desensitizing
d. Overloading
a. Ensure good RF shielding between the transmitter and receiver
b. Increase the transmitter audio gain
c. Decrease the receiver squelch gain
d. Increase the receiver bandwidth
405. What is cross-modulation interference?
c. The loudest signal received is the only demodulated signal
d. The weakest signal received is the only demodulated signal
410. What is a product detector?
a. A detector that provides local oscillator for input to the mixer
b. A detector that amplifies and narrows the bandpass frequencies
a. Interference between two transmitters of different modulation types
b. All signals on a frequency are demodulated by an AM receiver
404. How can receiver desensitizing be reduced?
a. All signals on a frequency are demodulated by an FM receiver
d. Inverted sidebands in the final stage of the amplifier
409. What is the capture effect?
c. A detector that uses mixing proc ess with a locally generated carrier
b. Interference caused by audio rectification in the
d. A detector used to detect cross -modulation products
receiver preamp
411. What is the term used to refer to the reception blockage of
c. Decrease the receiver squelch gain
one FM-phone signal?
d. Modulation from an unwanted signal is heard in
a. Desensitization
addition to the desired signal
b. Cross-modulation interference
c. Capture effect
d. Frequency discrimination
412. What is the process of detection?
418. What occurs in a receiver when an excessive amount of signal energy reaches the mixer circuit?
a. The process of masking out the intelligence on a
a. Spurious mixer products are generated
received carrier to make an S-meter operational
b. Mixer blanking occurs
b. The recovery of intelligence from the modulated RF
c. Automatic limiting occurs
signal
d. A beat frequency is generated
c. The modulation of a carrier
419. How much gain should be used in the RF amplifier stage
d. The mixing of noise with the received signal
of a receiver?
413. What is the principle of detection in a diode detector?
a. Rectification and filtering of RF
b. Breakdown of the Zener voltage
c. Mixing with the noise in the transition region of the
a. As much as possible short of self oscillation
b. Sufficient gain to allow weak signals to overcome noise generated in the first mixer
diode
d. The change of reactance in the diode with respect
noise of the first mixer stage
to frequency 414. How are FM phone signals detected?
c. Sufficient gain to keep weak signals below the
d. It depends on the amplification factor of the first IF stage
420. Why should the RF amplifier stage of a receiver only have
a. By a balanced modulator
sufficient gain to allow weak signals to overcome noise
b. By a frequency discriminator
generated in the first mixer stage?
c. By a product detector
d. By a phase s plitter
415. What is the mixing process?
a. To prevent the sum and difference frequencies from being generated
b. To prevent bleed-through of the desired signal
a. The elimination of noise in a wideband receiver by
c. To prevent generation of spurious mixer products
phase comparison
d. To prevent bleed-trough of the local oscillator
b. The elimination of noise in a wideband receiver by
421. What is the primary purpose of an RF amplifier in a
phase differentiation
receiver?
c. Distortion caused by aural propagation
a. To provide most of the receiver gain
d. The combination of the two signals to produce s um
b. To vary the receiver image rejection by utilizing the
and difference frequencies 416. What is a frequency discriminator?
AGC
c. To improve the receiver’s noise figure
d. To develop the AGC voltage
a. A circuit for detecting FM signals
b. A circuit for filtering two closely adjacent signals
c. An automatic band switching circuit
a. A fixed-tuned passband amplifier
d. An FM generator
b. A receiver demodulator
417. What are the principal frequencies which appear at the
c. A receiver filter
output of a mixer circuit?
d. A buffer oscillator
422. What is an IF amplifier stage?
a. Two and four times the srcinal frequency
423. What factors should be considered when selecting an
b. The sum, difference and square root of the input
intermediate frequency?
frequencies
a. A cross-modulation distortion and interference
c. The srcinal frequencies and the sum and
b. Interference to other services
difference frequencies
c. Image rejection and selectivity
d. 1.414 and 0.707 times the frequency
d. Noise figure and distortion
424. What is the primary purpose of the first IF amplifier stage
in a receiver?
c. Cross-modulation of the desired signal and insufficient audio power to operate the speaker
a. A noise figure performance
b. Tune out cross-modulation distortion
c. Dynamic response
430. What is the term for the ratio between the largest tolerable
d. Selectivity
receiver input signal and the minimum discernible signal?
d. Oscillator instability and severe audio distortion of all but the strongest signal received signals
425. What is the primary purpose of the final IF amplifier stage
a. Intermodulation distortion
in a receiver?
b. Noise floor
a. Dynamic response
c. Noise figure
b. Gain
d. Dynamic range
c. Noise figure performance
431. What occurs during CW reception if too narrow a filter
d. Bypass undesired signals
bandwidth is used in the IF stage of a receiver?
426. Which stage of a receiver primarily establishes its noise
a. Undesired signals will reach the audio s tage
figure?
b. Output-offset overshoot
a. The audio stage
c. Cross-modulation distortion
b. The IF stage
d. Filter ringing
c. The RF stage
432. How can selectivity be achieved in the front and circuitry
d. The local oscillator
of a communications receiver?
427. What is meant by the term noise figure in a
a. By using an audio filter
communications receiver?
b. By using a pre-selector
a. The level of noise entering the receiver from the
c. By using an additional RF amplifier stage
antenna
d. By using an additional IF amplifier stage
b. The relative strength of a strength of a re ceived
433. How should the filter bandwidth of a receiver IF section
signal 3 kHz removed from the carrier frequency
compare with the bandwidth of a received signal?
c. The level of noise generated in the front end and
succeeding stages of a receiver
d. The ability of a receiver to reject unwanted signals
received signal bandwidth
at frequencies close to the desired one 428. The ability of a communications receiver to perform well in
b. Filter bandwidth should be approximately half the received signal bandwidth
the presence of strong signals outside the band of interest is indicated by what parameter?
a. Filter bandwidth should be slightly greater than the
c. Filter bandwidth should be approximately two times the received signal bandwidth
d. Filter bandwidth should be approximately four times
a. Noise figure
b. Blocking dynamic range
434. How can receiver selectivity be achieved in the IF circuitry
the received signal bandwidth
c. Signal-to-noise ratio
of a communications receiver?
d. Audio output
429. What type problems are caused by poor dynamic range in a communications receiver?
to the local oscillator circuitry
a. Cross-modulation of the desired signal and desensitization from strong adjacent signals
should it be transmitted
b. Replace the standard JFET mixer with a bipolar transistor followed by a capacitor of the proper value
b. Oscillator instability requiring frequent returning, and loss of ability to recover the opposite sideband
a. Incorporate a means of varying the supply voltage
c. Remove AGC action from the IF stage and confine it to the audio stage only
d. Incorporate a high-Q filter
435. A receiver has a sensitivity of 0.6 microvolts and a
441. What parameter must be selected when designing an
blocking dynamic range of 60 dB. W hat is the strongest signal
audio filter using an op-amp?
that can be present along with a 0.6 microvolt signal without
a. Bandwidth characteristics
blocking taking place
b. Desired current gain
a. 600 millivolts
c. Temperature coefficient
b. 600 microvolts
d. Output-offset overshoot
c. 300 millivolts
d. 300 mircovolts
442. What two factors determine the sensitivity of a receiver?
a. Dynamic range and third-order intercept
436. An AM receiver is tuned to broadcast station at 600 kHz.
b. Cost and availability
Calculate the image rejection in dB assuming that the input
c. Intermodulation distortion and dynamic range
filter consists of one tuned circuit with a Q of 40?
d. Bandwidth and noise figure
a. 19.28 dB
443. How can unwanted ringing and audio instability be
b. 39.65 dB
prevented in a multi-section op-amp RC audio filter circuit?
c. 38.57 dB
a. Restrict both gain and Q
d. 19.83 dB
b. Restrict gain, but increase Q
437. A receiver has two uncoupled tuned circuits before the
c. Restrict Q but increase gain
mixer, each with a Q of 75. The signal frequency is 100.1 MHz.
d. Increase both gain and Q
The IF is 10.7 Mhz. The local oscillator uses high-side
444. What is meant by the dynamic range of a communications
injection. Calculate the image rejection ratio.
receiver?
a. 23.69 dB
b. 58.66 dB
c. 29.33 dB
d. 11.84 dB
438. What oscillator frequency is needed to heterodyne 626
highest frequency to which the receiver can be tuned
a. 2.954 MHz
b. 4.832 MHz
c. 4.210 MHz
d. 2.328 MHz
b. The maximum possible undistorted audio output of the receiver referenced to one milliwatt
kHz up to 3.58 MHz?
a. The number of kHz between the lowest and the
c. The ratio between the minimum discernible signal and the largest tolerable signal without causing audible distortion products
d. The difference between the lowest frequency signal detectable without moving the tuning knob
445. Where is the noise which primarily dete rmines the signal-
439. What is the undesirable effect of using too wide a filter
to-noise ratio in a VHF (150 MHz) marine band receiver
bandwidth in the IF section of a receiver?
generated?
a. Output-offset overshoot
a. In the receiver front end
b. Undesired signals will reach the audio s tage
b. Man-made noise
c. Thermal noise distortion
c. In the atmosphere
d. Filter ringing
d. In the ionosphere
440. What is the limiting condition for sensitivity in a
446. An AM receiver uses a diode detector for demodulation.
communications receiver?
This enables it satisfactorily to receive
a. the noise floor of the receiver
a. Single-sideband, suppressed carrier (J3E)
b. the power supply output ripple
b. Single-sideband, reduced carrier (R3E)
c. the two-tone intermodulation distorting
c. ISB(B8E)
d. the input impedance to the detector
d. Single-sideband, full carrier (H3E)
447. Three-point tracking is achieved with
a. Variable selectivity
454. It is the process of changing the amplitude of a relative
b. The padder capacitor
high frequency carrier signal in proportion with the
c. Double spotting
instantaneous value of the modulating signal.
d. Double conversion
a. frequency modulation
448. A receiver has poor IF selectivity. It will therefore also
b. digital modulation
have poor
c. phase modulation
d. analog modulation
a. Blocking
b. Double-spotting
c. Diversity reception
a. carrier
d. Sensitivity
b. upper sideband
449. If a FET is used as the first AF amplifier in a transistor
c. lower sideband
receiver, this will have the effect of
d. modulating signal
455. Most of the power in an AM signal is in the
a. Gain variation over the frequency coverage range
b. Insufficient gain and selectivity
a. linear mixing
c. Inadequate selectivity at high frequencies
b. analog multiplexing
d. Instability
c. signal summation
d. multiplexing
450. The image frequency of a superheterodyne receiver
456. Amplitude modulation is the same as
a. Is created within the receiver itself
457. The shape of the amplitude-modulated wave is called
b. Is due to insufficient adjacent channel rejection
______.
c. Is not rejected by the IF tuned circuits
a. sidebands
d. Is independent of the frequency to which receiver is
b. modulating signal
tuned
c. envelope
d. carrier signal
451. The process of impressing a low frequency information signals onto a high-frequency carrier signal is called _____.
458. In a diode modulator, the negative half of the AM wave is
a. demodulation
b. oscillation
a. tuned circuit
c. modulation
b. transformer
d. amplification
c. capacitor
d. inductor
452. A silicon varactor diode exhibits a c apacitance of 200pF
supplied by
at zero bias. If it is in parallel with a 60-pF capacitor and a 200-
459. It is a term used to describe the amount of amplitude
uH inductor, calculate the range of resonant frequency as the
change present in an AM waveform.
diode varies through a reverse bias of 3 to 15V.
a. coefficient of modulation
a. 679 kHz to 2.13 MHz
b. modulation index
b. 966 kHz to 1.15 MHz
c. depth of modulation
c. 355 kHz to 3.12 MHz
d. any of these
d. 143 kHz to 4.53 MHz
453. A process where the received s ignal is transformed into its srcinal form.
460. When the modulation index in an AM wave is greater than one it will cause _______.
a. buck-shot
a. demodulation
b. splatter
b. damping
c. overmodulation
c. amplification
d. any of these
d. oscillation
461. The ideal value of modulation index in AM.
a. 1
c. low-level modulation
b. 0
d. high-level modulation
c. 100
468. If a superheterodyne receiver is tuned to a desired signal
d. infinity
at 1000kHz and its conversion (local) oscillator is operating at
462. When the amplitude of the information in an AM
1300kHz, what would be the frequency of an incoming signal
modulator is equal to zero, what is the value of the modulation
that would possibly cause image reception?
index?
a. 1600 kHz
a. 1
b. 2300 kHz
b. 0
c. 1250 kHz
c. 100
d. 3420 kHz
d. infinity
463. Amplitude modulation can be produced by
469. When modulation requires a much higher amplitude modulating signal to achieve a reasonable percent modulation,
a. having the carrier vary a resistance
b. having the modulating signal vary a c apacitance
a. high-level modulation
c. varying the carrier frequency
b. low-level modulation
d. varying the gain of the amplifier
c. zero-modulation
d. constant modulation
464. When the modulation index is equal to zero, the total transmitted power is equal to ________.
this is called
470. Amplitude modulators that vary the carrier amplitude with
a. one of the sidebands
the modulating signal by passing it through an attenuator work
b. carrier
on principle of
c. double sidebands
a. rectification
d. an AM wave
b. resonance
465. When the modulation takes place prior to the output
c. variable resistance
element of the final stage of the transmitter, prior to the
d. absorption
collector of the output transistor in a transistorized transmitter,
471. A circuit which function is to raise the amplitude of the
this is called ______.
source signal to a usable level while producing minimum
a. high-level modulation
b. low-level modulation
a. power amplifier
c. zero-modulation
b. non-linear amplifier
d. constant modulation
c. buffer amplifier
d. preamplifier
466. A circuit that monitors the received signal level and sends
nonlinear distortion adding as little thermal noise as possible.
a signal back to the RF and IF amplifiers to adjust their gain
472. A circuit that has a low-gain, high-input impedance linear
automatically.
amplifier which is used to isolate the oscillator from the high-
a. automatic phase control
b. automatic gain control
a. power amplifier
c. automatic frequency control
b. bandpass filter
d. automatic volume control
c. signal driver
d. buffer amplifier
467. When the modulation takes place in the final element of
power amplifiers.
the final stage where the carrier signal is a t its maximum
473. With high-level transmitters, which of the following is not a
amplitude, it is called _____.
primary function of the modulator circuit?
a. constant modulation
b. zero-modulation
a. it provides the capacity necessary for modulation to occur
b. it serves as a final amplifier
480. A receiver has a dynamic range of 81 dB. It has 0.55nW
c. it serves as a frequency up-converter
sensitivity. Determine the maximum allowable input signal.
d. it serves as a mixer
a. 59 mW
474. It is a form of amplitude distortion introduced when
b. 69 mW
positive and negative alternations in the AM modulated signal
c. 79 mW
are not equal.
d. 88 mW
a. phase shift
481. The information sources modulate the same carrier after it
b. carrier shift
has been separated into two carrier signals are at 90 degrees
c. amplitude variations
out of phase with each other.
d. frequency shift
a. QPSK
475. A carrier is simultaneously modulated by two sine waves
b. QUAM
with modulation indices of 0.3 and 0.4, the total modulation
c. PSK
index
d. FSK
a. is 1
482. Demodulating quadrature AM signal requires a carrier
b. cannot be calculated unless the phase relations are
recovery circuit to reproduce the srcinal carrier frequency and
known
phase and two balanced modulators to actually demodulate
c. is 0.5
the signals. This is called ________.
d. is 0.7
a. asynchronous detection
476. The component used to produce AM AT very high
b. quadrature demodulation
frequencies is a
c. synchronous detection
d. quadrature detection
a. varactor
b. thermistor
483. Quadrature amplitude modulation is also known as
c. cavity resonator
________.
d. PIN diode
477. It is also known as upward modulation
a. phase division multiplexing
b. phase division modulation
a. carrier shift
c. phase amplitude multiplexing
b. amplitude variations
d. phase angle modulation
c. frequency shift
484. Amplitude modulation generated at a very low voltage or
d. phase shift
power amplitude is known as
478. Also known as downward modulation
a. high-level modulation
a. carrier shift
b. low-level modulation
b. amplitude variations
c. collector modulation
c. frequency shift
d. minimum modulation
d. phase shift
479. It is a form of amplitude modulation where signals from
485. It is the first stage of the receiver and is therefore often called the receiver front end.
two separate information sources modulate the same carrier
a. mixer
frequency at the same time without interfering with each other.
b. RF section
a. QPSK
c. local oscillator
b. QUAM
d. IF stage
c. PSK
d. FSK
486. In an SSB transmitter, one is most likely to find a
a. class C audio amplifier
b. tuned modulator
c. class B RF amplifier
b. m = 1
d. class A RF output amplifier
c. m < 1
d. m > 1
487. The section of the receiver than down-c onverts the received RF frequencies to intermediate frequencies.
494. Why are limiters used in FM receivers?
a. RF section
a. provide better noise performance
b. local oscillator
b. clip noise peaks
c. power amplifier
c. prevent overdrive of discriminators
d. mixer
d. any of these
488. The circuit that demodulates the AM wave and converts it to the srcinal information signal.
495. Why are limiters used in FM transmitters?
a. clip noise peaks
a. power amplifier
b. prevent overdrive of discriminators
b. local oscillator
c. prevent overdeviation
c. detector
d. any of these
d. IF section
496. It is defined as the difference in decibels between the
489. A collector modulator has a supply voltage of 48 V. The
minimum input level necessary to discern the s ignal and the
peak-to-peak amplitude of the modulating signal for 100
input level that will overdrive the receiver and produce
percent modulation is
distortion.
a. 24 V
a. dynamic range
b. 48 V
b. noise figure
c. 96 V
c. bandwidth efficiency
d. 120 V
d. bandwidth improvement
490. What signals might feed into an FM broadc ast station
497. It is the input power range over which the receiver is
audio control console?
useful.
a. microphones
a. dynamic range
b. turntables
b. noise figure
c. remote lines
c. bandwidth efficiency
d. any of these
d. bandwidth improvement
491. The noise reduction ratio achieved by reducing the
498. It is defined as the output power when the RF amplifier
bandwidth is called
response is 1-dB less than the ideal linear gain response.
a. dynamic range
a. 1-dB compression point
b. noise figure
b. 1-dB threshold point
c. bandwidth efficiency
c. 1-dB shoot-off point
d. bandwidth improvement
d. 1-dB pinch-off point
492. It is the minimum RF signal level that can be detected at
499. It is the measure of the ability of a communications
the input to the receiver and still produce a usable
system to produce, at the output of the receiver, an exact
demodulated information signal.
replica of the srcinal source information.
a. selectivity
a. sensitivity
b. sensitivity
b. threshold
c. Q-factor
c. selectivity
d. bandwidth
d. fidelity
493. For ideal AM, which of the following is true
a. m = 0
