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FCC ADVANCED Exam Question Pool. Subelement 4AG.
Practical Circuits. 10 Questions.
---------------------------------------------------
4AG 1.1 D
What is a linear electronic voltage regulator?
A. A regulator that has a ramp voltage as its output
B. A regulator in which the pass transistor switches from the "off" state to
the "on" state
C. A regulator in which the control device is switched on or off, with the
duty cycle proportional to the line or load conditions
D. A regulator in which the conduction of a control element is varied in
direct proportion to the line voltage or load current
4AG 1.2 C
What is a switching electronic voltage regulator?
A. A regulator in which the conduction of a control element is varied in
direct proportion to the line voltage or load current
B. A regulator that provides more than one output voltage
C. A regulator in which the control device is switched on or off, with the
duty cycle proportional to the line or load conditions
D. A regulator that gives a ramp voltage at its output
4AG 1.3 A
What device is usually used as a stable reference voltage in a linear
voltage regulator?
A. A Zener diode
B. A tunnel diode
C. An SCR
D. A varactor diode
4AG 1.4 B
What type of linear regulator is used in applications requiring efficient
utilization of the primary power source?
A. A constant current source
B. A series regulator
C. A shunt regulator
D. A shunt current source
4AG 1.5 D
What type of linear voltage regulator is used in applications where the load
on the unregulated voltage source must be kept constant?
A. A constant current source
B. A series regulator
C. A shunt current source
D. A shunt regulator
4AG 1.6 C
To obtain the best temperature stability, what should be the operating
voltage of the reference diode in a linear voltage regulator?
A. Approximately 2.0 volts
B. Approximately 3.0 volts
C. Approximately 6.0 volts
D. Approximately 10.0 volts
4AG 1.7 A
What is the meaning of the term remote sensing with regard to a linear
voltage regulator?
A. The feedback connection to the error amplifier is made directly to the
load
B. Sensing is accomplished by wireless inductive loops
C. The load connection is made outside the feedback loop
D. The error amplifier compares the input voltage to the reference voltage
4AG 1.8 D
What is a three-terminal regulator?
A. A regulator that supplies three voltages with variable current
B. A regulator that supplies three voltages at a constant current
C. A regulator containing three error amplifiers and sensing transistors
D. A regulator containing a voltage reference, error amplifier, sensing
resistors and transistors, and a pass element
4AG 1.9 B
What are the important characteristics of a three-terminal regulator?
A. Maximum and minimum input voltage, minimum output current and voltage
B. Maximum and minimum input voltage, maximum output current and voltage
C. Maximum and minimum input voltage, minimum output current and maximum
output voltage
D. Maximum and minimum input voltage, minimum output voltage and maximum
output current
4AG 2.1 B
What is the distinguishing feature of a Class A amplifier?
A. Output for less than 180 degrees of the signal cycle
B. Output for the entire 360 degrees of the signal cycle
C. Output for more than 180 degrees and less than 360 degrees of the signal
cycle
D. Output for exactly 180 degrees of the input signal cycle
4AG 2.2 A
What class of amplifier is distinguished by the presence of output
throughout the entire signal cycle and the input never goes into the cutoff
region?
A. Class A
B. Class B
C. Class C
D. Class D
4AG 2.3 D
What is the distinguishing characteristic of a Class B amplifier?
A. Output for the entire input signal cycle
B. Output for greater than 180 degrees and less than 360 degrees of the
input signal cycle
C. Output for less than 180 degrees of the input signal cycle
D. Output for 180 degrees of the input signal cycle
4AG 2.4 B
What class of amplifier is distinguished by the flow of current in the
output essentially in 180 degree pulses?
A. Class A
B. Class B
C. Class C
D. Class D
4AG 2.5 A
What is a Class AB amplifier?
A. Output is present for more than 180 degrees but less than 360 degrees of
the signal input cycle
B. Output is present for exactly 180 degrees of the input signal cycle
C. Output is present for the entire input signal cycle
D. Output is present for less than 180 degrees of the input signal cycle
4AG 2.6 A
What is the distinguishing feature of a Class C amplifier?
A. Output is present for less than 180 degrees of the input signal cycle
B. Output is present for exactly 180 degrees of the input signal cycle
C. Output is present for the entire input signal cycle
D. Output is present for more than 180 degrees but less than 360 degrees of
the input signal cycle
4AG 2.7 C
What class of amplifier is distinguished by the bias being set well beyond
cutoff?
A. Class A
B. Class B
C. Class C
D. Class AB
4AG 2.8 C
Which class of amplifier provides the highest efficiency?
A. Class A
B. Class B
C. Class C
D. Class AB
4AG 2.9 A
Which class of amplifier has the highest linearity and least distortion?
A. Class A
B. Class B
C. Class C
D. Class AB
4AG 2.10 D
Which class of amplifier has an operating angle of more than 180 degrees but
less than 360 degrees when driven by a sine wave signal?
A. Class A
B. Class B
C. Class C
D. Class AB
4AG 3.1 B
What is an L-network?
A. A network consisting entirely of four inductors
B. A network consisting of an inductor and a capacitor
C. A network used to generate a leading phase angle
D. A network used to generate a lagging phase angle
4AG 3.2 D
What is a pi-network?
A. A network consisting entirely of four inductors or four capacitors
B. A Power Incidence network
C. An antenna matching network that is isolated from ground
D. A network consisting of one inductor and two capacitors or two inductors
and one capacitor
4AG 3.3 B
What is a pi-L-network?
A. A Phase Inverter Load network
B. A network consisting of two inductors and two capacitors
C. A network with only three discrete parts
D. A matching network in which all components are isolated from ground
4AG 3.4 D
Does the L-, pi-, or pi-L-network provide the greatest harmonic suppression?
A. L-network
B. Pi-network
C. Inverse L-network
D. Pi-L-network
4AG 3.5 C
What are the three most commonly used networks to accomplish a match between
an amplifying device and a transmission line?
A. M-network, pi-network and T-network
B. T-network, M-network and Q-network
C. L-network, pi-network and pi-L-network
D. L-network, M-network and C-network
4AG 3.6 D
How are networks able to transform one impedance to another?
A. Resistances in the networks substitute for resistances in the load
B. The matching network introduces negative resistance to cancel the
resistive part of an impedance
C. The matching network introduces transconductance to cancel the reactive
part of an impedance
D. The matching network can cancel the reactive part of an impedance and
change the value of the resistive part of an impedance
4AG 3.7 B
Which type of network offers the greater transformation ratio?
A. L-network
B. Pi-network
C. Constant-K
D. Constant-M
4AG 3.8 A
Why is the L-network of limited utility in impedance matching?
A. It matches a small impedance range
B. It has limited power handling capabilities
C. It is thermally unstable
D. It is prone to self resonance
4AG 3.9 D
What is an advantage of using a pi-L-network instead of a pi-network for
impedance matching between the final amplifier of a vacuum-tube type
transmitter and a multiband antenna?
A. Greater transformation range
B. Higher efficiency
C. Lower losses
D. Greater harmonic suppression
4AG 3.10 C
Which type of network provides the greatest harmonic suppression?
A. L-network
B. Pi-network
C. Pi-L-network
D. Inverse-Pi network
4AG 4.1 A
What are the three general groupings of filters?
A. High-pass, low-pass and band-pass
B. Inductive, capacitive and resistive
C. Audio, radio and capacitive
D. Hartley, Colpitts and Pierce
4AG 4.2 C
What is a constant-K filter?
A. A filter that uses Boltzmann's constant
B. A filter whose velocity factor is constant over a wide range of
frequencies
C. A filter whose product of the series- and shunt-element impedances is a
constant for all frequencies
D. A filter whose input impedance varies widely over the design bandwidth
4AG 4.3 A
What is an advantage of a constant-k filter?
A. It has high attenuation for signals on frequencies far removed from the
passband
B. It can match impedances over a wide range of frequencies
C. It uses elliptic functions
D. The ratio of the cutoff frequency to the trap frequency can be varied
4AG 4.4 D
What is an m-derived filter?
A. A filter whose input impedance varies widely over the design bandwidth
B. A filter whose product of the series- and shunt-element impedances is a
constant for all frequencies
C. A filter whose schematic shape is the letter "M"
D. A filter that uses a trap to attenuate undesired frequencies too near
cutoff for a constant-k filter.
4AG 4.5 C
What are the distinguishing features of a Butterworth filter?
A. A filter whose product of the series- and shunt-element impedances is a
constant for all frequencies
B. It only requires capacitors
C. It has a maximally flat response over its passband
D. It requires only inductors
4AG 4.6 B
What are the distinguishing features of a Chebyshev filter?
A. It has a maximally flat response over its passband
B. It allows ripple in the passband
C. It only requires inductors
D. A filter whose product of the series- and shunt-element impedances is a
constant for all frequencies
4AG 4.7 B
When would it be more desirable to use an m-derived filter over a constant-k
filter?
A. When the response must be maximally flat at one frequency
B. When you need more attenuation at a certain frequency that is too close
to the cut-off frequency for a constant-k filter
C. When the number of components must be minimized
D. When high power levels must be filtered
4AG 5.1 C
What condition must exist for a circuit to oscillate?
A. It must have a gain of less than 1
B. It must be neutralized
C. It must have positive feedback sufficient to overcome losses
D. It must have negative feedback sufficient to cancel the input
4AG 5.2 D
What are three major oscillator circuits often used in amateur radio
equipment?
A. Taft, Pierce and negative feedback
B. Colpitts, Hartley and Taft
C. Taft, Hartley and Pierce
D. Colpitts, Hartley and Pierce
4AG 5.3 D
How is the positive feedback coupled to the input in a Hartley oscillator?
A. Through a neutralizing capacitor
B. Through a capacitive divider
C. Through link coupling
D. Through a tapped coil
4AG 5.4 C
How is the positive feedback coupled to the input in a Colpitts oscillator?
A. Through a tapped coil
B. Through link coupling
C. Through a capacitive divider
D. Through a neutralizing capacitor
4AG 5.5 D
How is the positive feedback coupled to the input in a Pierce oscillator?
A. Through a tapped coil
B. Through link coupling
C. Through a capacitive divider
D. Through capacitive coupling
4AG 5.6 D
Which of the three major oscillator circuits used in amateur radio equipment
utilizes a quartz crystal?
A. Negative feedback
B. Hartley
C. Colpitts
D. Pierce
4AG 5.7 A
What is the piezoelectric effect?
A. Mechanical vibration of a crystal by the application of a voltage
B. Mechanical deformation of a crystal by the application of a magnetic
field
C. The generation of electrical energy by the application of light
D. Reversed conduction states when a P-N junction is exposed to light
4AG 5.8 B
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 a high output power
4AG 5.9 B
Which type of oscillator circuit is commonly used in a VFO?
A. Pierce
B. Colpitts
C. Hartley
D. Negative feedback
4AG 5.10 C
Why is the Colpitts oscillator circuit commonly used in a VFO?
A. The frequency is a linear function of the load impedance
B. It can be used with or without crystal lock-in
C. It is stable
D. It has high output power
4AG 6.1 D
What is meant by the term modulation?
A. The squelching of a signal until a critical signal-to-noise ratio is
reached
B. Carrier rejection through phase nulling
C. A linear amplification mode
D. A mixing process whereby information is imposed upon a carrier
4AG 6.2 B
How is an F3E FM-phone emission produced?
A. With a balanced modulator on the audio amplifier
B. With a reactance modulator on the oscillator
C. With a reactance modulator on the final amplifier
D. With a balanced modulator on the oscillator
4AG 6.3 C
What is a reactance modulator?
A. A circuit that acts as a variable resistance or capacitance to produce FM
signals
B. A circuit that acts as a variable resistance or capacitance to produce AM
signals
C. A circuit that acts as a variable inductance or capacitance to produce FM
signals
D. A circuit that acts as a variable inductance or capacitance to produce AM
signals
4AG 6.4 B
What is a balanced modulator?
A. An FM modulator that produces a balanced deviation
B. A modulator that produces a double sideband, suppressed carrier signal
C. A modulator that produces a single sideband, suppressed carrier signal
D. A modulator that produces a full carrier signal
4AG 6.5 D
How can a single-sideband phone signal be generated?
A. By driving a product detector with a DSB signal
B. By using a reactance modulator followed by a mixer
C. By using a loop modulator followed by a mixer
D. By using a balanced modulator followed by a filter
4AG 6.6 D
How can a double-sideband phone signal be generated?
A. By feeding a phase modulated signal into a low pass filter
B. By using a balanced modulator followed by a filter
C. By detuning a Hartley oscillator
D. By modulating the plate voltage of a class C amplifier
4AG 7.1 A
How is the efficiency of a power amplifier determined?
A. Efficiency = ( RF power out / DC power in ) X 100%
B. Efficiency = ( RF power in / RF power out ) X 100%
C. Efficiency = ( RF power in / DC power in ) X 100%
D. Efficiency = ( DC power in / RF power in ) X 100%
4AG 7.2 B
For reasonably efficient operation of a vacuum tube Class C amplifier, what
should the plate-load resistance be with 1500-volts at the plate and 500-
milliamperes plate current?
A. 2000 ohms
B. 1500 ohms
C. 4800 ohms
D. 480 ohms
4AG 7.3 C
For reasonably efficient operation of a vacuum-tube Class B amplifier, what
should the plate-load resistance be with 800-volts at the plate and 75-
milliamperes plate current?
A. 679.4 ohms
B. 60 ohms
C. 6794 ohms
D. 10,667 ohms
4AG 7.4 A
For reasonably efficient operation of a vacuum tube Class A amplifier, what
should the plate-load resistance be with 250-volts at the plate and 25-
milliamperes plate current?
A. 7692 ohms
B. 3250 ohms
C. 325 ohms
D. 769.2 ohms
4AG 7.5 B
For reasonably efficient operation of a transistor amplifier, what should
the load resistance be with 12-volts at the collector and 5 watts power
output?
A. 100.3 ohms
B. 14.4 ohms
C. 10.3 ohms
D. 144 ohms
4AG 7.6 B
What is the flywheel effect?
A. The continued motion of a radio wave through space when the transmitter
is turned off
B. The back and forth oscillation of electrons in an LC circuit
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
4AG 7.7 C
How can a power amplifier be neutralized?
A. By increasing the grid drive
B. By feeding back an in-phase component of the output to the input
C. By feeding back an out-of-phase component of the output to the input
D. By feeding back an out-of-phase component of the input to the output
4AG 7.8 B
What order of Q is required by a tank-circuit sufficient to reduce harmonics
to an acceptable level?
A. Approximately 120
B. Approximately 12
C. Approximately 1200
D. Approximately 1.2
4AG 7.9 C
How can parasitic oscillations be eliminated from a power amplifier?
A. By tuning for maximum SWR
B. By tuning for maximum power output
C. By neutralization
D. By tuning the output
4AG 7.10 D
What is the procedure for tuning a power amplifier having an output pi-
network?
A. Adjust the loading capacitor to maximum capacitance and then dip the
plate current with the tuning capacitor
B. Alternately increase the plate current with the tuning capacitor and dip
the plate current with the loading capacitor
C. Adjust the tuning capacitor to maximum capacitance and then dip the plate
current with the loading capacitor
D. Alternately increase the plate current with the loading capacitor and dip
the plate current with the tuning capacitor
4AG 8.1 B
What is the process of detection?
A. The process of masking out the intelligence on a received carrier to make
an S-meter operational
B. The recovery of intelligence from the modulated RF signal
C. The modulation of a carrier
D. The mixing of noise with the received signal
4AG 8.2 A
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 noise in the transition region of the diode
D. The change of reactance in the diode with respect to frequency
4AG 8.3 C
What is a product detector?
A. A detector that provides local oscillations for input to the mixer
B. A detector that amplifies and narrows the band-pass frequencies
C. A detector that uses a mixing process with a locally generated carrier
D. A detector used to detect cross-modulation products
4AG 8.4 B
How are FM-phone signals detected?
A. By a balanced modulator
B. By a frequency discriminator
C. By a product detector
D. By a phase splitter
4AG 8.5 A
What is a frequency discriminator?
A. A circuit for detecting FM signals
B. A circuit for filtering two closely adjacent signals
C. An automatic bandswitching circuit
D. An FM generator
4AG 8.6 D
What is the mixing process?
A. The elimination of noise in a wideband receiver by phase comparison
B. The elimination of noise in a wideband receiver by phase differentiation
C. Distortion caused by auroral propagation
D. The combination of two signals to produce sum and difference frequencies
4AG 8.7 C
What are the principal frequencies which appear at the output of a mixer
circuit?
A. Two and four times the original frequency
B. The sum, difference and square root of the input frequencies
C. The original frequencies and the sum and difference frequencies
D. 1.414 and 0.707 times the input frequency
4AG 8.8 B
What are the advantages of the frequency-conversion process?
A. Automatic squelching and increased selectivity
B. Increased selectivity and optimal tuned-circuit design
C. Automatic soft limiting and automatic squelching
D. Automatic detection in the RF amplifier and increased selectivity
4AG 8.9 A
What occurs in a receiver when an excessive amount of signal energy reaches
the mixer circuit?
A. Spurious mixer products are generated
B. Mixer blanking occurs
C. Automatic limiting occurs
D. A beat frequency is generated
4AG 9.1 B
How much gain should be used in the RF amplifier stage of a receiver?
A. As much gain as possible short of self oscillation
B. Sufficient gain to allow weak signals to overcome noise generated in the
first mixer stage
C. Sufficient gain to keep weak signals below the noise of the first mixer
stage
D. It depends on the amplification factor of the first IF stage
4AG 9.2 C
Why should the RF amplifier stage of a receiver only have sufficient gain to
allow weak signals to overcome noise generated in the first mixer stage?
A. To prevent the sum and difference frequencies from being generated
B. To prevent bleed-through of the desired signal
C. To prevent the generation of spurious mixer products
D. To prevent bleed-through of the local oscillator
4AG 9.3 C
What is the primary purpose of an RF amplifier in a receiver?
A. To provide most of the receiver gain
B. To vary the receiver image rejection by utilizing the AGC
C. To improve the receiver's noise figure
D. To develop the AGC voltage
4AG 9.4 A
What is an i-f amplifier stage?
A. A fixed-tuned pass-band amplifier
B. A receiver demodulator
C. A receiver filter
D. A buffer oscillator
4AG 9.5 C
What factors should be considered when selecting an intermediate frequency?
A. Cross-modulation distortion and interference
B. Interference to other services
C. Image rejection and selectivity
D. Noise figure and distortion
4AG 9.6 D
What is the primary purpose of the first i-f amplifier stage in a receiver?
A. Noise figure performance
B. Tune out cross-modulation distortion
C. Dynamic response
D. Selectivity
4AG 9.7 B
What is the primary purpose of the final i-f amplifier stage in a receiver?
A. Dynamic response
B. Gain
C. Noise figure performance
D. Bypass undesired signals
4AG 10.1 C
What type of circuit is shown in Figure 4AG-10?
A. Switching voltage regulator
B. Linear voltage regulator
C. Common emitter amplifier
D. Emitter follower amplifier
4AG 10.2 B
In Figure 4AG-10, what is the purpose of R1 and R2?
A. Load resistors
B. Fixed bias
C. Self bias
D. Feedback
4AG 10.3 D
In Figure 4AG-10, what is the purpose of C1?
A. Decoupling
B. Output coupling
C. Self bias
D. Input coupling
4AG 10.4 D
In Figure 4AG-10, what is the purpose of C3?
A. AC feedback
B. Input coupling
C. Power supply decoupling
D. Emitter bypass
4AG 10.5 D
In Figure 4AG-10, what is the purpose of R3?
A. Fixed bias
B. Emitter bypass
C. Output load resistor
D. Self bias
4AG 11.1 B
What type of circuit is shown in Figure 4AG-11?
A. High-gain amplifier
B. Common-collector amplifier
C. Linear voltage regulator
D. Grounded-emitter amplifier
4AG 11.2 A
In Figure 4AG-11, what is the purpose of R?
A. Emitter load
B. Fixed bias
C. Collector load
D. Voltage regulation
4AG 11.3 D
In Figure 4AG-11, what is the purpose of C1?
A. Input coupling
B. Output coupling
C. Emitter bypass
D. Collector bypass
4AG 11.4 A
In Figure 4AG-11, what is the purpose of C2?
A. Output coupling
B. Emitter bypass
C. Input coupling
D. Hum filtering
4AG 12.1 C
What type of circuit is shown in Figure 4AG-12?
A. Switching voltage regulator
B. Grounded emitter amplifier
C. Linear voltage regulator
D. Emitter follower
4AG 12.2 B
What is the purpose of D1 in the circuit shown in Figure 4AG-12?
A. Line voltage stabilization
B. Voltage reference
C. Peak clipping
D. Hum filtering
4AG 12.3 C
What is the purpose of Q1 in the circuit shown in Figure 4AG-12?
A. It increases the output ripple
B. It provides a constant load for the voltage source
C. It increases the current handling capability
D. It provides D1 with current
4AG 12.4 D
What is the purpose of C1 in the circuit shown in Figure 4AG-12?
A. It resonates at the ripple frequency
B. It provides fixed bias for Q1
C. It decouples the output
D. It filters the supply voltage
4AG 12.5 A
What is the purpose of C2 in the circuit shown in Figure 4AG-12?
A. It bypasses hum around D1
B. It is a brute force filter for the output
C. To self resonate at the hum frequency
D. To provide fixed DC bias for Q1
4AG 12.6 A
What is the purpose of C3 in the circuit shown in Figure 4AG-12?
A. It prevents self-oscillation
B. It provides brute force filtering of the output
C. It provides fixed bias for Q1
D. It clips the peaks of the ripple
4AG 12.7 C
What is the purpose of R1 in the circuit shown in Figure 4AG-12?
A. It provides a constant load to the voltage source
B. It couples hum to D1
C. It supplies current to D1
D. It bypasses hum around D1
4AG 12.8 D
What is the purpose of R2 in the circuit shown in Figure 4AG-12?
A. It provides fixed bias for Q1
B. It provides fixed bias for D1
C. It decouples hum from D1
D. It provides a constant minimum load for Q1
4AG 13.1 C
What value capacitor would be required to tune a 20-microhenry inductor to
resonate in the 80-meter wavelength band?
A. 150 picofarads
B. 200 picofarads
C. 100 picofarads
D. 100 microfarads
4AG 13.2 D
What value inductor would be required to tune a 100-picofarad capacitor to
resonate in the 40-meter wavelength band?
A. 200 microhenrys
B. 150 microhenrys
C. 5 millihenrys
D. 5 microhenrys
4AG 13.3 A
What value capacitor would be required to tune a 2-microhenry inductor to
resonate in the 20-meter wavelength band?
A. 64 picofarads
B. 6 picofarads
C. 12 picofarads
D. 88 microfarads
4AG 13.4 C
What value inductor would be required to tune a 15-picofarad capacitor to
resonate in the 15-meter wavelength band?
A. 2 microhenrys
B. 30 microhenrys
C. 4 microhenrys
D. 15 microhenrys
4AG 13.5 A
What value capacitor would be required to tune a 100-microhenry inductor to
resonate in the 160-meter wavelength band?
A. 78 picofarads
B. 25 picofarads
C. 405 picofarads
D. 40.5 microfarads
--------------------------------------------------
End of Subelement 4AG.