Practical Circuits Flashcards
Which term describes the ability of a receiver to detect the presence of a signal?
A. Linearity
B. Sensitivity
C. Selectivity
D. Total Harmonic Distortion
B. Sensitivity
What is a transceiver?
A. A device that combines a receiver and transmitter
B. A device for matching feed line impedance to 50 ohms
C. A device for automatically sending and decoding Morse code
D. A device for converting receiver and transmitter frequencies to another band
A. A device that combines a receiver and transmitter
Which of the following is used to convert a signal from one frequency to another?
A. Phase splitter
B. Mixer
C. Inverter
D. Amplifier
B. Mixer
Which term describes the ability of a receiver to discriminate between multiple signals?
A. Discrimination ratio
B. Sensitivity
C. Selectivity
D. Harmonic distortion
C. Selectivity
What is the name of a circuit that generates a signal at a specific frequency?
A. Reactance modulator
B. Phase modulator
C. Low-pass filter
D. Oscillator
D. Oscillator
What device converts the RF input and output of a transceiver to another band?
A. High-pass filter
B. Low-pass filter
C. Transverter
D. Phase converter
C. Transverter
This question wants to know what electrical circuit converts a lower frequency Single-Side-Band (SSB) frequency to a higher frequency. This is done by aTransverter. The other choices will not convert one frequency to another.
A high-pass filter will reduce a signal’s amplitude if it is not higher than the corner frequency of the filter.
A low-pass filter will reduce a signal’s amplitude if it is not lower than the corner frequency of the filter.
A phase converter will alter the phase of a signal but the frequency will stay the same.
What is the function of a transceiver’s PTT input?
A. Input for a key used to send CW
B. Switches transceiver from receive to transmit when grounded
C. Provides a transmit tuning tone when grounded
D. Input for a preamplifier tuning tone
B. Switches transceiver from receive to transmit when grounded
Push-to-talk (PTT), also known as press-to-transmit, is a method of having conversations or talking on half-duplex communication lines, including two-way radio, using a momentary button to switch from voice reception mode to transmit mode.
Which of the following describes combining speech with an RF carrier signal?
A. Impedance matching
B. Oscillation
C. Modulation
D. Low-pass filtering
C. Modulation
What is the function of the SSB/CW-FM switch on a VHF power amplifier?
A. Change the mode of the transmitted signal
B. Set the amplifier for proper operation in the selected mode
C. Change the frequency range of the amplifier to operate in the proper segment of the band
D. Reduce the received signal noise
B. Set the amplifier for proper operation in the selected mode
What device increases the transmitted output power from a transceiver?
A. A voltage divider
B. An RF power amplifier
C. An impedance network
D. All these choices are correct
B. An RF power amplifier
Where is an RF preamplifier installed?
A. Between the antenna and receiver
B. At the output of the transmitter power amplifier
C. Between the transmitter and the antenna tuner
D. At the output of the receiver audio amplifier
A. Between the antenna and receiver
What can you do if you are told your FM handheld or mobile transceiver is over-deviating?
A. Talk louder into the microphone
B. Let the transceiver cool off
C. Change to a higher power level
D. Talk farther away from the microphone
D. Talk farther away from the microphone
What would cause a broadcast AM or FM radio to receive an amateur radio transmission unintentionally?
A. The receiver is unable to reject strong signals outside the AM or FM band
B. The microphone gain of the transmitter is turned up too high
C. The audio amplifier of the transmitter is overloaded
D. The deviation of an FM transmitter is set too low
A. The receiver is unable to reject strong signals outside the AM or FM band
Which of the following can cause radio frequency interference?
A. Fundamental overload
B. Harmonics
C. Spurious emissions
D. All these choices are correct
D. All these choices are correct
Which of the following could you use to cure distorted audio caused by RF current on the shield of a microphone cable?
A. Band-pass filter
B. Low-pass filter
C. Preamplifier
D. Ferrite choke
D. Ferrite choke
Ferrite beads, often called Ferrite chokes or Ferrite rings, are passive electronic components that help suppress radio frequency interference (RFI) on a power supply line.
How can fundamental overload of a non-amateur radio or TV receiver by an amateur signal be reduced or eliminated?
A. Block the amateur signal with a filter at the antenna input of the affected receiver
B. Block the interfering signal with a filter on the amateur transmitter
C. Switch the transmitter from FM to SSB
D. Switch the transmitter to a narrow-band mode
A. Block the amateur signal with a filter at the antenna input of the affected receiver
Which of the following actions should you take if a neighbor tells you that your station’s transmissions are interfering with their radio or TV reception?
A. Make sure that your station is functioning properly and that it does not cause interference to your own radio or television when it is tuned to the same channel
B. Immediately turn off your transmitter and contact the nearest FCC office for assistance
C. Install a harmonic doubler on the output of your transmitter and tune it until the interference is eliminated
D. All these choices are correct
A. Make sure that your station is functioning properly and that it does not cause interference to your own radio or television when it is tuned to the same channel
Which of the following can reduce overload of a VHF transceiver by a nearby commercial FM station?
A. Installing an RF preamplifier
B. Using double-shielded coaxial cable
C. Installing bypass capacitors on the microphone cable
D. Installing a band-reject filter
D. Installing a band-reject filter
What should you do if something in a neighbor’s home is causing harmful interference to your amateur station?
A. Work with your neighbor to identify the offending device
B. Politely inform your neighbor that FCC rules prohibit the use of devices that cause interference
C. Make sure your station meets the standards of good amateur practice
D. All these choices are correct
D. All these choices are correct
What should be the first step to resolve non-fiber optic cable TV interference caused by your amateur radio transmission?
A. Add a low-pass filter to the TV antenna input
B. Add a high-pass filter to the TV antenna input
C. Add a preamplifier to the TV antenna input
D. Be sure all TV feed line coaxial connectors are installed properly
D. Be sure all TV feed line coaxial connectors are installed properly
What might be a problem if you receive a report that your audio signal through an FM repeater is distorted or unintelligible?
A. Your transmitter is slightly off frequency
B. Your batteries are running low
C. You are in a bad location
D. All these choices are correct
D. All these choices are correct
What is a symptom of RF feedback in a transmitter or transceiver?
A. Excessive SWR at the antenna connection
B. The transmitter will not stay on the desired frequency
C. Reports of garbled, distorted, or unintelligible voice transmissions
D. Frequent blowing of power supply fuses
C. Reports of garbled, distorted, or unintelligible voice transmissions
What is the primary purpose of a dummy load?
A. To prevent transmitting signals over the air when making tests
B. To prevent over-modulation of a transmitter
C. To improve the efficiency of an antenna
D. To improve the signal-to-noise ratio of a receiver
A. To prevent transmitting signals over the air when making tests
Which of the following is 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
What does a dummy load consist of?
A. A high-gain amplifier and a TR switch
B. A non-inductive resistor mounted on a heat sink
C. A low-voltage power supply and a DC relay
D. A 50-ohm reactance used to terminate a transmission line
B. A non-inductive resistor mounted on a heat sink
What reading on an SWR meter indicates a perfect impedance match between the antenna and the feed line?
A. 50:50
B. Zero
C. 1:1
D. Full Scale
C. 1:1
The SWR meter measures the standing wave ratio (SWR) in a transmission line. The meter indirectly measures the degree of mismatch between a transmission line and its load (usually an antenna).
Why do most solid-state transmitters reduce output power as SWR increases beyond a certain level?
A. To protect the output amplifier transistors
B. To comply with FCC rules on spectral purity
C. Because power supplies cannot supply enough current at high SWR
D. To lower the SWR on the transmission line
A. To protect the output amplifier transistors
When your antenna system produces a higher SWR some of the power is reflected back to the transmitter; at higher power levels this can damage the transmitter. With older radios this was a common problem that needed to be protected against, but most solid-state (read: modern) transmitters automatically protect against that by reducing the power in cases of high SWR so that the reflected power will not cause damage to the transistors in the output amplifier.
What does an SWR reading of 4:1 indicate?
A. Loss of -4 dB
B. Good impedance match
C. Gain of +4 dB
D. Impedance mismatch
D. Impedance mismatch
What happens to power lost in a feed line?
A. It increases the SWR
B. It is radiated as harmonics
C. It is converted into heat
D. It distorts the signal
C. It is converted into heat
Which instrument can be used to determine SWR?
A. Voltmeter
B. Ohmmeter
C. Iambic pentameter
D. Directional wattmeter
D. Directional wattmeter
SWR is short forStanding Wave Ratio.
A directional wattmeter can be connected in-line to measure how much power (in watts) is flowing in a certain direction through a feedline. If the feedline and antenna are perfectly matched, you should have full power (whatever the transmitter is capable of)forward, with little or nonereflected.
This is becauseforwardpower indicates the power from the radio, and reverse orreflectedpower is the power that bounces back when it hits the improperly matched antenna.
Iambic pentameter is a commonly used type of metrical line in traditional English poetry and verse drama
Which of the following causes failure of coaxial cables?
A. Moisture contamination
B. Solder flux contamination
C. Rapid fluctuation in transmitter output power
D. Operation at 100% duty cycle for an extended period
A. Moisture contamination
Why should the outer jacket of coaxial cable be resistant to ultraviolet light?
A. Ultraviolet resistant jackets prevent harmonic radiation
B. Ultraviolet light can increase losses in the cable’s jacket
C. Ultraviolet and RF signals can mix, causing interference
D. Ultraviolet light can damage the jacket and allow water to enter the cable
D. Ultraviolet light can damage the jacket and allow water to enter the cable
What is a disadvantage of air core coaxial cable when compared to foam or solid dielectric types?
A. It has more loss per foot
B. It cannot be used for VHF or UHF antennas
C. It requires special techniques to prevent moisture in the cable
D. It cannot be used at below freezing temperatures
C. It requires special techniques to prevent moisture in the cable
Which instrument would you use to measure electric potential?
A. An ammeter
B. A voltmeter
C. A wavemeter
D. An ohmmeter
B. A voltmeter
How is a voltmeter connected to a component to measure applied voltage?
A. In series
B. In parallel
C. In quadrature
D. In phase
B. In parallel
When configured to measure current, how is a multimeter connected to a component?
A. In series
B. In parallel
C. In quadrature
D. In phase
A. In series
Which instrument is used to measure electric current?
A. An ohmmeter
B. An electrometer
C. A voltmeter
D. An ammeter
D. An ammeter
Which of the following can damage a multimeter?
A. Attempting to measure resistance using the voltage setting
B. Failing to connect one of the probes to ground
C. Attempting to measure voltage when using the resistance setting
D. Not allowing it to warm up properly
C. Attempting to measure voltage when using the resistance setting
Which of the following measurements are made using a multimeter?
A. Signal strength and noise
B. Impedance and reactance
C. Voltage and resistance
D. All these choices are correct
C. Voltage and resistance
Which of the following types of solder should not be used for radio and electronic applications?
A. Acid-core solder
B. Lead-tin solder
C. Rosin-core solder
D. Tin-copper solder
A. Acid-core solder
What is the characteristic appearance of a cold tin-lead solder joint?
A. Dark black spots
B. A bright or shiny surface
C. A rough or lumpy surface
D. Excessive solder
C. A rough or lumpy surface
What reading indicates that an ohmmeter is connected across a large, discharged capacitor?
A. Increasing resistance with time
B. Decreasing resistance with time
C. Steady full-scale reading
D. Alternating between open and short circuit
A. Increasing resistance with time
Which of the following precautions should be taken when measuring in-circuit resistance with an ohmmeter?
A. Ensure that the applied voltages are correct
B. Ensure that the circuit is not powered
C. Ensure that the circuit is grounded
D. Ensure that the circuit is operating at the correct frequency
B. Ensure that the circuit is not powered
