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What causes "tropospheric ducting"?
Temperature inversions in the atmosphere
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What is generally the best time for long-distance 10 meter band propagation?
During daylight hours
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What is the radio horizon?
The distance at which radio signals between two points are effectively blocked by the curvature of the Earth
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Why do VHF and UHF radio signals usually travel somewhat farther than the visual line of sight distance between two stations?
The Earth seems less curved to radio waves than to light
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Which of the following is true concerning the microphone connectors on amateur transceivers?
Some connectors include push-to-talk and voltages for powering the microphone
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What could be used in place of a regular speaker to help you copy signals in a noisy area?
A set of headphones
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Which is a good reason to use a regulated power supply for communications equipment?
It prevents voltage fluctuations from reaching sensitive circuits
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Where must a filter be installed to reduce harmonic emissions?
Between the transmitter and the antenna
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What type of filter should be connected to a TV receiver as the first step in trying to prevent RF overload from a nearby 2 meter transmitter?
Band-reject filter
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Which of the following would be connected between a transceiver and computer in a packet radio station?
Terminal node controller
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How is the computer’s sound card used when conducting digital communications using a computer?
The sound card provides audio to the microphone input and converts received audio to digital form
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Which type of conductor is best to use for RF grounding?
Flat strap
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Which would you use to reduce RF current flowing on the shield of an audio cable?
Ferrite choke
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What is the source of a high-pitched whine that varies with engine speed in a mobile transceiver’s receive audio?
The alternator
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Where should a mobile transceiver’s power negative connection be made?
At the battery or engine block ground strap
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What may happen if a transmitter is operated with the microphone gain set too high?
The output signal might become distorted
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Which of the following can be used to enter the operating frequency on a modern transceiver?
The keypad or VFO knob
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What is the purpose of the squelch control on a transceiver?
To mute receiver output noise when no signal is being received
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What is a way to enable quick access to a favorite frequency on your transceiver?
Store the frequency in a memory channel
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Which of the following would reduce ignition interference to a receiver?
Turn on the noise blanker
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Which of the following controls could be used if the voice pitch of a single-sideband signal seems too high or low?
The receiver RIT or clarifier
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What does the term "RIT" mean?
Receiver Incremental Tuning
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What is the advantage of having multiple receive bandwidth choices on a multimode transceiver?
Permits noise or interference reduction by selecting a bandwidth matching the mode
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Which of the following is an appropriate receive filter to select in order to minimize noise and interference for SSB reception?
2400 Hz
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Which of the following is an appropriate receive filter to select in order to minimize noise and interference for CW reception?
500 Hz
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Which of the following describes the common meaning of the term "repeater offset"?
The difference between the repeater’s transmit and receive frequencies
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Electrical current is measured in which of the following units?
Amperes
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Electrical power is measured in which of the following units?
Watts
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What is the name for the flow of electrons in an electric circuit?
Current
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What is the name for a current that flows only in one direction?
Direct current
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What is the electrical term for the electromotive force (EMF) that causes electron flow?
Voltage
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How much voltage does a mobile transceiver usually require?
About 12 volts
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Which of the following is a good electrical conductor?
Copper
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Which of the following is a good electrical insulator?
Glass
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What is the name for a current that reverses direction on a regular basis?
Alternating current
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Which term describes the rate at which electrical energy is used?
Power
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What is the basic unit of electromotive force?
The volt
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How many milliamperes is 1.5 amperes?
1,500 milliamperes
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What is another way to specify a radio signal frequency of 1,500,000 hertz?
1500 kHz
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How many volts are equal to one kilovolt?
One thousand volts
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How many volts are equal to one microvolt?
One one-millionth of a volt
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Which of the following is equivalent to 500 milliwatts?
0.5 watts
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If an ammeter calibrated in amperes is used to measure a 3000-milliampere current, what reading would it show?
3 amperes
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If a frequency readout calibrated in megahertz shows a reading of 3.525 MHz, what would it show if it were calibrated in kilohertz?
3525 kHz
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How many microfarads are 1,000,000 picofarads?
1 microfarad
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What is the approximate amount of change, measured in decibels (dB), of a power increase from 5 watts to 10 watts?
3 dB
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What is the approximate amount of change, measured in decibels (dB), of a power decrease from 12 watts to 3 watts?
6 dB
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What is the approximate amount of change, measured in decibels (dB), of a power increase from 20 watts to 200 watts?
10 dB
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What is the ability to store energy in an electric field called?
Capacitance
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What is the basic unit of capacitance?
The farad
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What is the ability to store energy in a magnetic field called?
Inductance
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What is the basic unit of inductance?
The henry
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What is the unit of frequency?
Hertz
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What is the abbreviation that refers to radio frequency signals of all types?
RF
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What is the usual name for electromagnetic waves that travel through space?
Radio waves
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What is the formula used to calculate electrical power in a DC circuit?
Power (P) equals voltage (E) multiplied by current (I)
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How much power is being used in a circuit when the applied voltage is 13.8 volts DC and the current is 10 amperes?
138 watts
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How much power is being used in a circuit when the applied voltage is 12 volts DC and the current is 2.5 amperes?
30 watts
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How many amperes are flowing in a circuit when the applied voltage is 12 volts DC and the load is 120 watts?
10 amperes
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What formula is used to calculate current in a circuit?
Current (I) equals voltage (E) divided by resistance (R)
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What formula is used to calculate voltage in a circuit?
Voltage (E) equals current (I) multiplied by resistance (R)
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What formula is used to calculate resistance in a circuit?
Resistance (R) equals voltage (E) divided by current (I)
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What is the resistance of a circuit in which a current of 3 amperes flows through a resistor connected to 90 volts?
30 ohms
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What is the resistance in a circuit for which the applied voltage is 12 volts and the current flow is 1.5 amperes?
8 ohms
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What is the resistance of a circuit that draws 4 amperes from a 12-volt source?
3 ohms
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What is the current flow in a circuit with an applied voltage of 120 volts and a resistance of 80 ohms?
1.5 amperes
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What is the current flowing through a 100-ohm resistor connected across 200 volts?
2 amperes
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What is the current flowing through a 24-ohm resistor connected across 240 volts?
10 amperes
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What is the voltage across a 2-ohm resistor if a current of 0.5 amperes flows through it?
1 volt
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What is the voltage across a 10-ohm resistor if a current of 1 ampere flows through it?
10 volts
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What is the voltage across a 10-ohm resistor if a current of 2 amperes flows through it?
20 volts
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