Technician test 4+ Flashcards
What should you do if another operator reports that your station’s 2 meter signals were strong just a moment ago, but now they are weak or distorted?
A. Change the batteries in your radio to a different type
B. Turn on the CTCSS tone
C. Ask the other operator to adjust his squelch control
D. Try moving a few feet or changing the direction of your antenna if possible, as reflections may be causing multi-path distortion
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D. Try moving a few feet or changing the direction of your antenna if possible, as reflections may be causing multi-path distortion
Why are UHF signals often more effective from inside buildings than VHF signals?
A. VHF signals lose power faster over distance
B. The shorter wavelength allows them to more easily penetrate the structure of buildings
C. This is incorrect; VHF works better than UHF inside buildings
D. UHF antennas are more efficient than VHF antennas
B. The shorter wavelength allows them to more easily penetrate the structure of buildings
What term is commonly used to describe the rapid fluttering sound sometimes heard from mobile stations that are moving while transmitting? A. Flip-flopping B. Picket fencing C. Frequency shifting D. Pulsing
B. Picket fencing
Which of the following is a likely cause of irregular fading of signals received by ionospheric reflection?
A. Frequency shift due to Faraday rotation
B. Interference from thunderstorms
C. Random combining of signals arriving via different paths
D. Intermodulation distortion
C. Random combining of signals arriving via different paths
What may occur if data signals propagate over multiple paths?
A. Transmission rates can be increased by a factor equal to the number of separate paths observed
B. Transmission rates must be decreased by a factor equal to the number of separate paths observed
C. No significant changes will occur if the signals are transmitting using FM
D. Error rates are likely to increase
D. Error rates are likely to increase
Which of the following effects might cause radio signals to be heard despite obstructions between the transmitting and receiving stations? A. Knife-edge diffraction B. Faraday rotation C. Quantum tunneling D. Doppler shift
A. Knife-edge diffraction
What mode is responsible for allowing over-the-horizon VHF and UHF communications to ranges of approximately 300 miles on a regular basis? A. Tropospheric scatter B. D layer refraction C. F2 layer refraction D. Faraday rotation
A. Tropospheric scatter
What causes tropospheric ducting?
A. Discharges of lightning during electrical storms
B. Sunspots and solar flares
C. Updrafts from hurricanes and tornadoes
D. Temperature inversions in the atmosphere
D. Temperature inversions in the atmosphere
What is the radio horizon?
A. The distance over which two stations can communicate by direct path
B. The distance from the ground to a horizontally mounted antenna
C. The farthest point you can see when standing at the base of your antenna tower
D. The shortest distance between two points on the Earth’s surface
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A. The distance over which two stations can communicate by direct path
Why do VHF and UHF radio signals usually travel somewhat farther than the visual line of sight distance between two stations?
A. Radio signals move somewhat faster than the speed of light
B. Radio waves are not blocked by dust particles
C. The Earth seems less curved to radio waves than to light
D. Radio waves are blocked by dust particles
C. The Earth seems less curved to radio waves than to light
Which part of the atmosphere enables the propagation of radio signals around the world? A. The stratosphere B. The troposphere C. The ionosphere D. The magnetosphere
C. The ionosphere
Why are direct (not via a repeater) UHF signals rarely heard from stations outside your local coverage area?
A. They are too weak to go very far
B. FCC regulations prohibit them from going more than 50 miles
C. UHF signals are usually not reflected by the ionosphere
D. They collide with trees and shrubbery and fade out
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C. UHF signals are usually not reflected by the ionosphere
Which of the following might be happening when VHF signals are being received from long distances?
A. Signals are being reflected from outer space
B. Signals are arriving by sub-surface ducting
C. Signals are being reflected by lightning storms in your area
D. Signals are being refracted from a sporadic E layer
D. Signals are being refracted from a sporadic E layer
What is a characteristic of VHF signals received via auroral reflection?
A. Signals from distances of 10,000 or more miles are common
B. The signals exhibit rapid fluctuations of strength and often sound distorted
C. These types of signals occur only during winter nighttime hours
D. These types of signals are generally strongest when your antenna is aimed west
B. The signals exhibit rapid fluctuations of strength and often sound distorted
Which of the following propagation types is most commonly associated with occasional strong over-the-horizon signals on the 10, 6, and 2 meter bands? A. Backscatter B. Sporadic E C. D layer absorption D. Gray-line propagation
B. Sporadic E
What band is best suited for communicating via meteor scatter? A. 10 meters B. 6 meters C. 2 meters D. 70 cm
B. 6 meters
What is generally the best time for long-distance 10 meter band propagation via the F layer?
A. From dawn to shortly after sunset during periods of high sunspot activity
B. From shortly after sunset to dawn during periods of high sunspot activity
C. From dawn to shortly after sunset during periods of low sunspot activity
D. From shortly after sunset to dawn during periods of low sunspot activity
A. From dawn to shortly after sunset during periods of high sunspot activity
Which of the following bands may provide long distance communications during the peak of the sunspot cycle? A. Six or ten meters B. 23 centimeters C. 70 centimeters or 1.25 meters D. All of these choices are correct
A. Six or ten meters
What is the approximate amount of change, measured in decibels (dB), of a power increase from 5 watts to 10 watts? A. 2 dB B. 3 dB C. 5 dB D. 10 dB
B. 3 dB
What is the approximate amount of change, measured in decibels (dB), of a power decrease from 12 watts to 3 watts? A. -1 dB B. -3 dB C. -6 dB D. -9 dB
C. -6 dB
What is the approximate amount of change, measured in decibels (dB), of a power increase from 20 watts to 200 watts? A. 10 dB B. 12 dB C. 18 dB D. 28 dB
A. 10 dB
What can happen if the antennas at opposite ends of a VHF or UHF line of sight radio link are not using the same polarization?
A. The modulation sidebands might become inverted
B. Signals could be significantly weaker
C. Signals have an echo effect on voices
D. Nothing significant will happen
B. Signals could be significantly weaker
What type of wave carries radio signals between transmitting and receiving stations? A. Electromagnetic B. Electrostatic C. Surface acoustic D. Magnetostrictive
A. Electromagnetic
Which of the following results from the fact that skip signals refracted from the ionosphere are elliptically polarized?
A. Digital modes are unusable
B. Either vertically or horizontally polarized antennas may be used for transmission or reception
C. FM voice is unusable
D. Both the transmitting and receiving antennas must be of the same polarization
B. Either vertically or horizontally polarized antennas may be used for transmission or reception
What property of a radio wave is used to describe its polarization?
A. The orientation of the electric field
B. The orientation of the magnetic field
C. The ratio of the energy in the magnetic field to the energy in the electric field
D. The ratio of the velocity to the wavelength
A. The orientation of the electric field
What are the two components of a radio wave? A. AC and DC B. Voltage and current C. Electric and magnetic fields D. Ionizing and non-ionizing radiation
C. Electric and magnetic fields
What is a usual name for electromagnetic waves that travel through space? A. Gravity waves B. Sound waves C. Radio waves D. Pressure waves
C. Radio waves
Which of the following is true regarding vertical antennas?
A. The magnetic field is perpendicular to the Earth
B. The electric field is perpendicular to the Earth
C. The phase is inverted
D. The phase is reversed
B. The electric field is perpendicular to the Earth
What is meant by the gain of an antenna?
A. The additional power that is added to the transmitter power
B. The additional power that is lost in the antenna when transmitting on a higher frequency
C. The increase in signal strength in a specified direction when compared to a reference antenna
D. The increase in impedance on receive or transmit compared to a reference antenna
C. The increase in signal strength in a specified direction when compared to a reference antenna
Which of the following instruments can be used to determine if an antenna is resonant at the desired operating frequency? A. A VTVM B. An antenna analyzer C. A Q meter D. A frequency counter
B. An antenna analyzer
Which of the following is a common use of coaxial cable?
A. Carrying dc power from a vehicle battery to a mobile radio
B. Carrying RF signals between a radio and antenna
C. Securing masts, tubing, and other cylindrical objects on towers
D. Connecting data signals from a TNC to a computer
B. Carrying RF signals between a radio and antenna
What is the impedance of the most commonly used coaxial cable in typical amateur radio installations? A. 8 ohms B. 50 ohms C. 600 ohms D. 12 ohms
B. 50 ohms
Why is coaxial cable used more often than any other feed line for amateur radio antenna systems?
A. It is easy to use and requires few special installation considerations
B. It has less loss than any other type of feed line
C. It can handle more power than any other type of feed line
D. It is less expensive than any other types of feed line
A. It is easy to use and requires few special installation considerations
What generally happens as the frequency of a signal passing through coaxial cable is increased?
A. The apparent SWR increases
B. The reflected power increases
C. The characteristic impedance increases
D. The loss increases
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D. The loss increases
Which of the following types of feed line has the lowest loss at VHF and UHF? A. 50-ohm flexible coax B. Multi-conductor unbalanced cable C. Air-insulated hard line D. 75-ohm flexible coax
C. Air-insulated hard line
What, in general terms, is standing wave ratio (SWR)?
A. A measure of how well a load is matched to a transmission line
B. The ratio of high to low impedance in a feed line
C. The transmitter efficiency ratio
D. An indication of the quality of your station’s ground connection
A. A measure of how well a load is matched to a transmission line
What reading on an SWR meter indicates a perfect impedance match between the antenna and the feed line? A. 2 to 1 B. 1 to 3 C. 1 to 1 D. 10 to 1
C. 1 to 1
What is the approximate SWR value above which the protection circuits in most solid-state transmitters begin to reduce transmitter power? A. 2 to 1 B. 1 to 2 C. 6 to 1 D. 10 to 1
A. 2 to 1
What does an SWR reading of 4:1 indicate? A. Loss of -4dB B. Good impedance match C. Gain of +4dB D. Impedance mismatch
D. Impedance mismatch
Why is it important to have a low SWR in an antenna system that uses coaxial cable feed line?
A. To reduce television interference
B. To allow the efficient transfer of power and reduce losses
C. To prolong antenna life
D. All of these choices are correct
B. To allow the efficient transfer of power and reduce losses
What might cause erratic changes in SWR readings?
A. The transmitter is being modulated
B. A loose connection in an antenna or a feed line
C. The transmitter is being over-modulated
D. Interference from other stations is distorting your signal
B. A loose connection in an antenna or a feed line
Which of the following describes a simple dipole mounted so the conductor is parallel to the Earth's surface? A. A ground wave antenna B. A horizontally polarized antenna C. A rhombic antenna D. A vertically polarized antenna
B. A horizontally polarized antenna
What is a disadvantage of the “rubber duck” antenna supplied with most handheld radio transceivers?
A. It does not transmit or receive as effectively as a full-sized antenna
B. It transmits a circularly polarized signal
C. If the rubber end cap is lost it will unravel very quickly
D. All of these choices are correct
A. It does not transmit or receive as effectively as a full-sized antenna
How would you change a dipole antenna to make it resonant on a higher frequency?
A. Lengthen it
B. Insert coils in series with radiating wires
C. Shorten it
D. Add capacitive loading to the ends of the radiating wires
C. Shorten it
What is a good reason not to use a “rubber duck” antenna inside your car?
A. Signals can be significantly weaker than when it is outside of the vehicle
B. It might cause your radio to overheat
C. The SWR might decrease, decreasing the signal strength
D. All of these choices are correct
A. Signals can be significantly weaker than when it is outside of the vehicle
What is the approximate length, in inches, of a quarter-wavelength vertical antenna for 146 MHz? A. 112 B. 50 C. 19 D. 12
C. 19
What is the approximate length, in inches, of a 6 meter 1/2-wavelength wire dipole antenna? A. 6 B. 50 C. 112 D. 236
C. 112
In which direction is the radiation strongest from a half-wave dipole antenna in free space? A. Equally in all directions B. Off the ends of the antenna C. Broadside to the antenna D. In the direction of the feed line
C. Broadside to the antenna
What is a reason to use a properly mounted 5/8 wavelength antenna for VHF or UHF mobile service?
A. It offers a lower angle of radiation and more gain than a 1/4 wavelength antenna and usually provides improved coverage
B. It features a very high angle of radiation and is better for communicating via a repeater
C. The 5/8 wavelength antenna completely eliminates distortion caused by reflected signals
D. The 5/8 wavelength antenna offers a 10-times power gain over a 1/4 wavelength design
A. It offers a lower angle of radiation and more gain than a 1/4 wavelength antenna and usually provides improved coverage
Why are VHF or UHF mobile antennas often mounted in the center of the vehicle roof?
A. Roof mounts have the lowest possible SWR of any mounting configuration
B. Only roof mounting can guarantee a vertically polarized signal
C. A roof mounted antenna normally provides the most uniform radiation pattern
D. Roof mounted antennas are always the easiest to install
C. A roof mounted antenna normally provides the most uniform radiation pattern
Which of the following terms describes a type of loading when referring to an antenna?
A. Inserting an inductor in the radiating portion of the antenna to make it electrically longer
B. Inserting a resistor in the radiating portion of the antenna to make it resonant
C. Installing a spring at the base of the antenna to absorb the effects of collisions with other objects
D. Making the antenna heavier so it will resist wind effects when in motion
A. Inserting an inductor in the radiating portion of the antenna to make it electrically longer