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1992-01-26
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FCC EXTRA Exam Question Pool. Subelement 4BD.
Amateur Radio Practice. 4 Questions.
---------------------------------------------------
4BD 1A1 C
How does a spectrum analyzer differ from a conventional
time-domain oscilloscope?
A. An oscilloscope is used to display electrical signals
while the spectrum analyzer is used to measure ionospheric
reflection
B. An oscilloscope is used to display electrical signals
in the frequency domain while the spectrum analyzer is
used to display electrical signals in the time domain
C. An oscilloscope is used to display electrical signals
in the time domain while the spectrum analyzer is used
to display electrical signals in the frequency domain
D. An oscilloscope is used to displaying audio frequencies
and the spectrum analyzer is used for displaying radio
frequencies
4BD 1A2 D
What does the horizontal axis of a spectrum analyzer display?
A. Amplitude
B. Voltage
C. Resonance
D. Frequency
4BD 1A3 A
What does the vertical axis of a spectrum analyzer display?
A. Amplitude
B. Duration
C. Frequency
D. Time
4BD 1B1 A
What test instrument can be used to display spurious signals in
the output of a radio transmitter?
A. A spectrum analyzer
B. A wattmeter
C. A logic analyzer
D. A time-domain reflectometer
4BD 1B2 B
What test instrument is used to display intermodulation
distortion products from a SSB transmitter?
A. A wattmeter
B. A spectrum analyzer
C. A logic analyzer
D. A time-domain reflectometer
4BD 2A1 D
What advantage does a logic probe have over a voltmeter
for monitoring logic states in a circuit?
A. A logic probe has fewer leads to connect to a circuit
than a voltmeter
B. A logic probe can be used to test analog and digital
circuits
C. A logic probe can be powered by commercial ac lines
D. A logic probe is smaller and shows a simplified readout
4BD 2A2 C
What piece of test equipment can be used to directly
indicate high and low logic states?
A. A galvanometer
B. An electroscope
C. A logic probe
D. A Wheatstone bridge
4BD 2A3 D
What is a logic probe used to indicate?
A. A short-circuit fault in a digital-logic circuit
B. An open-circuit failure in a digital-logic circuit
C. A high-impedance ground loop
D. High and low logic states in a digital-logic circuit
4BD 2B1 A
What piece of test equipment besides an oscilloscope can be
used to indicate pulse conditions in a digital-logic circuit?
A. A logic probe
B. A galvanometer
C. An electroscope
D. A Wheatstone bridge
4BD 3A1 A
What is one of the most significant problems you might
encounter when you try to receive signals with a mobile
station?
A. Ignition noise
B. Doppler shift
C. Radar interference
D. Mechanical vibrations
4BD 3A2 A
What is the proper procedure for suppressing electrical
noise in a mobile station?
A. Apply shielding and filtering where necessary
B. Insulate all plane sheet metal surfaces from each other
C. Apply antistatic spray liberally to all non-metallic
surfaces
D. Install filter capacitors in series with all dc wiring
4BD 3A3 C
How can ferrite beads be used to suppress ignition noise?
A. Install them in the resistive high voltage cable every 2
years
B. Install them between the starter solenoid and the starter
motor
C. Install them in the primary and secondary ignition leads
D. Install them in the antenna lead to the radio
4BD 3A4 D
How can ensuring good electrical contact between connecting
metal surfaces in a vehicle reduce spark plug noise?
A. It reduces the spark gap distance, causing a lower
frequency spark
B. It helps radiate the spark plug noise away from the
vehicle
C. It reduces static buildup on the vehicle
D. It encourages lower frequency electrical resonances
in the vehicle
4BD 3B1 B
How can alternator whine be minimized?
A. By connecting the the radio's power leads to the battery
by the longest possible path
B. By connecting the the radio's power leads to the battery
by the shortest possible path
C. By installing a high pass filter in series with the radio's
dc power lead to the vehicle's electrical system
D. By installing filter capacitors in series with the dc power
lead
4BD 3B2 D
How can conducted and radiated noise caused by an automobile
alternator be suppressed?
A. By installing filter capacitors in series with the dc
power lead and by installing a blocking capacitor in the
field lead
B. By connecting the radio's power leads to the battery by
the longest possible path and by installing a blocking
capacitor in series with the positive lead
C. By installing a high pass filter in series with the radio's
power lead to the vehicle's electrical system and by installing
a low pass filter in parallel with the field lead
D. By connecting the radio's power lead directly to the battery
and by installing coaxial capacitors in the alternator leads
4BD 3C1 B
What is a major cause of atmospheric static?
A. Sunspots
B. Thunderstorms
C. Airplanes
D. Meteor showers
4BD 3D1 C
How can you determine if a line-noise interference problem is
being generated within your home?
A. Check the power-line voltage with a time-domain reflectometer
B. Observe the ac waveform on an oscilloscope
C. Turn off the main circuit breaker and listen on a battery-
operated radio
D. Observe the power-line voltage on a spectrum analyzer
4BD 4.1 A
What is the main drawback of a wire-loop antenna for
direction finding?
A. It has a bidirectional pattern broadside to the loop
B. It is non-rotatable
C. It receives equally well in all directions
D. It is practical for use only on VHF bands
4BD 4.2 B
What directional pattern is desirable for a direction-finding
antenna?
A. A non-cardioid pattern
B. Good front-to-back and front-to-side ratios
C. Good top-to-bottom and and front-to-side ratios
D. Shallow nulls
4BD 4.3 C
What is the triangulation method of direction finding?
A. Using the geometric angle of ground waves and sky waves
emanating from the same source to locate the signal source
B. A fixed receiving station uses three beam headings to plot
the signal source on a map
C. Beam headings from several receiving locations are used
to plot the signal source on a map
D. The use of three vertical antennas to indicate the location
of the signal source
4BD 4.4 D
Why is an RF attenuator desirable in a receiver used for
direction finding?
A. It narrows the bandwidth of the received signal
B. It eliminates the effects of isotropic radiation
C. It reduces loss of received signals caused by antenna
pattern nulls
D. It prevents receiver overload from extremely strong
signals
4BD 4.5 A
What is a sense antenna?
A. A vertical antenna added to a loop antenna to produce a
cardioid reception pattern
B. A horizontal antenna added to a loop antenna to produce
a cardioid reception pattern
C. A vertical antenna added to a Adcock antenna to produce
an omnidirectional reception pattern
D. A horizontal antenna added to a Adcock antenna to produce
a cardioid reception pattern
4BD 4.6 D
What type of antenna is most useful for sky-wave reception
in radio direction finding?
A. A log-periodic dipole array
B. An isotropic antenna
C. A circularly polarized antenna
D. An Adcock antenna
4BD 4.7 C
What is a loop antenna?
A. A circularly polarized antenna
B. A coil of wire used as an antenna in FM broadcast
receivers
C. A wire loop used in radio direction finding
D. An antenna coupled to the feed line through an
inductive loop of wire
4BD 4.8 D
How can the output voltage of loop antenna be increased?
A. By reducing the permeability of the loop shield
B. By increasing the number of wire turns in the loop
while reducing the area of the loop structure
C. By reducing either the number of wire turns in the
loop, or the area of the loop structure
D. By increasing either the number of wire turns in the
loop, or the area of the loop structure
4BD 4.9 B
Why is an antenna system with a cardioid pattern desirable
for a direction-finding system?
A. The broad side responses of the cardioid pattern can be
aimed at the desired station
B. The deep null of the cardioid pattern can pinpoint the
direction of the desired station
C. The sharp peak response of the cardioid pattern can
pinpoint the direction of the desired station
D. The high radiation angle of the cardioid pattern is
useful for short-distance direction finding
4BD 4.10 C
What type of terrain can cause errors in direction finding?
A. Homogeneous terrain
B. Smooth grassy terrain
C. Varied terrain
D. Terrain with no buildings of mountains
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End of Subelement 4BD.