G7 – PRACTICAL CIRCUITS [3 Exam Questions – 3 Groups] Flashcards
What useful feature does a power supply bleeder resistor provide?
A. It acts as a fuse for excess voltage
B. It ensures that the filter capacitors are discharged when power is removed
C. It removes shock hazards from the induction coils
D. It eliminates ground loop current
G7A01 (B)
B. It ensures that the filter capacitors are discharged when power is removed
Which of the following components are used in a power supply filter network?
A. Diodes
B. Transformers and transducers
C. Quartz crystals
D. Capacitors and inductors
G7A02 (D)
D. Capacitors and inductors
Which type of rectifier circuit uses two diodes and a center-tapped transformer?
A. Full-wave
B. Full-wave bridge
C. Half-wave
D. Synchronous
G7A03 (A)
A. Full-wave
What is an advantage of a half-wave rectifier in a power supply?
A. Only one diode is required
B. The ripple frequency is twice that of a full-wave rectifier
C. More current can be drawn from the half-wave rectifier
D. The output voltage is two times the peak output voltage of the transformer
G7A04 (A)
A. Only one diode is required
What portion of the AC cycle is converted to DC by a half-wave rectifier?
A. 90 degrees
B. 180 degrees
C. 270 degrees
D. 360 degrees
G7A05 (B)
B. 180 degrees
What portion of the AC cycle is converted to DC by a full-wave rectifier?
A. 90 degrees
B. 180 degrees
C. 270 degrees
D. 360 degrees
G7A06 (D)
D. 360 degrees
What is the output waveform of an unfiltered full-wave rectifier connected to a resistive load?
A. A series of DC pulses at twice the frequency of the AC input
B. A series of DC pulses at the same frequency as the AC input
C. A sine wave at half the frequency of the AC input
D. A steady DC voltage
G7A07 (A)
A. A series of DC pulses at twice the frequency of the AC input
Which of the following is an advantage of a switchmode power supply as compared to a linear power supply?
A. Faster switching time makes higher output voltage possible
B. Fewer circuit components are required
C. High-frequency operation allows the use of smaller components
D. All these choices are correct
G7A08(C)
C. High-frequency operation allows the use of smaller components
Which symbol in figure G7-1 represents a field effect transistor?
A. Symbol 2
B. Symbol 5
C. Symbol 1
D. Symbol 4
G7A09 (C)
C. Symbol 1
Which symbol in figure G7-1 represents a Zener diode?
A. Symbol 4
B. Symbol 1
C. Symbol 11
D. Symbol 5
G7A10 (D)
D. Symbol 5
Which symbol in figure G7-1 represents an NPN junction transistor?
A. Symbol 1
B. Symbol 2
C. Symbol 7
D. Symbol 11
G7A11 (B)
B. Symbol 2
Which symbol in Figure G7-1 represents a solid core transformer?
A. Symbol 4
B. Symbol 7
C. Symbol 6
D. Symbol 1
G7A12 (C)
C. Symbol 6
Which symbol in Figure G7-1 represents a tapped inductor?
A. Symbol 7
B. Symbol 11
C. Symbol 6
D. Symbol 1
G7A13 (A)
A. Symbol 7
What is the reason for neutralizing the final amplifier stage of a transmitter?
A. To limit the modulation index
B. To eliminate self-oscillations
C. To cut off the final amplifier during standby periods
D. To keep the carrier on frequency
G7B01 (B)
B. To eliminate self-oscillations
Which of these classes of amplifiers has the highest efficiency?
A. Class A
B. Class B
C. Class AB
D. Class C
G7B02 (D)
D. Class C
Which of the following describes the function of a two-input AND gate?
A. Output is high when either or both inputs are low
B. Output is high only when both inputs are high
C. Output is low when either or both inputs are high
D. Output is low only when both inputs are high
G7B03 (B)
B. Output is high only when both inputs are high
Which of the following describes the function of a two input NOR gate?
A. Output is high when either or both inputs are low
B. Output is high only when both inputs are high
C. Output is low when either or both inputs are high
D. Output is low only when both inputs are high
G7B04 (C)
C. Output is low when either or both inputs are high
How many states does a 3-bit binary counter have?
A. 3
B. 6
C. 8
D. 16
G7B05 (C)
C. 8
What is a shift register?
A. A clocked array of circuits that passes data in steps along the array
B. An array of operational amplifiers used for tri-state arithmetic operations
C. A digital mixer
D. An analog mixer
G7B06 (A)
A. A clocked array of circuits that passes data in steps along the array
Which of the following are basic components of a sine wave oscillator?
A. An amplifier and a divider
B. A frequency multiplier and a mixer
C. A circulator and a filter operating in a feed-forward loop
D. A filter and an amplifier operating in a feedback loop
G7B07 (D)
D. A filter and an amplifier operating in a feedback loop
How is the efficiency of an RF power amplifier determined?
A. Divide the DC input power by the DC output power
B. Divide the RF output power by the DC input power
C. Multiply the RF input power by the reciprocal of the RF output power
D. Add the RF input power to the DC output power
G7B08 (B)
B. Divide the RF output power by the DC input power
What determines the frequency of an LC oscillator?
A. The number of stages in the counter
B. The number of stages in the divider
C. The inductance and capacitance in the tank circuit
D. The time delay of the lag circuit
G7B09 (C)
C. The inductance and capacitance in the tank circuit
Which of the following describes a linear amplifier?
A. Any RF power amplifier used in conjunction with an amateur transceiver
B. An amplifier in which the output preserves the input waveform
C. A Class C high efficiency amplifier
D. An amplifier used as a frequency multiplier
G7B10 (B)
B. An amplifier in which the output preserves the input waveform
For which of the following modes is a Class C power stage appropriate for amplifying a modulated signal?
A. SSB
B. FM
C. AM
D. All these choices are correct
G7B11 (B)
B. FM
Which of the following is used to process signals from the balanced modulator then send them to the mixer in some single sideband phone transmitters?
A. Carrier oscillator
B. Filter
C. IF amplifier
D. RF amplifier
G7C01 (B)
B. Filter
Which circuit is used to combine signals from the carrier oscillator and speech amplifier then send the result to the filter in some single sideband phone transmitters?
A. Discriminator
B. Detector
C. IF amplifier
D. Balanced modulator
G7C02 (D)
D. Balanced modulator
What circuit is used to process signals from the RF amplifier and local oscillator then send the result to the IF filter in a superheterodyne receiver?
A. Balanced modulator
B. IF amplifier
C. Mixer
D. Detector
G7C03 (C)
C. Mixer
What circuit is used to combine signals from the IF amplifier and BFO and send the result to the AF amplifier in some single sideband receivers?
A. RF oscillator
B. IF filter
C. Balanced modulator
D. Product detector
G7C04 (D)
D. Product detector
Which of the following is an advantage of a direct digital synthesizer (DDS)?
A. Wide tuning range and no need for band switching
B. Relatively high-power output
C. Relatively low power consumption
D. Variable frequency with the stability of a crystal oscillator
G7C05 (D)
D. Variable frequency with the stability of a crystal oscillator
What should be the impedance of a low-pass filter as compared to the impedance of the transmission line into which it is inserted?
A. Substantially higher
B. About the same
C. Substantially lower
D. Twice the transmission line impedance
G7C06 (B)
B. About the same
What is the simplest combination of stages that implement a superheterodyne receiver?
A. RF amplifier, detector, audio amplifier
B. RF amplifier, mixer, IF discriminator
C. HF oscillator, mixer, detector
D. HF oscillator, prescaler, audio amplifier
G7C07 (C)
C. HF oscillator, mixer, detector
What circuit is used in analog FM receivers to convert IF output signals to audio?
A. Product detector
B. Phase inverter
C. Mixer
D. Discriminator
G7C08 (D)
D. Discriminator
What is the phase difference between the I and Q signals that software-defined radio (SDR) equipment uses for modulation and demodulation?
A. Zero
B. 90 degrees
C. 180 degrees
D. 45 degrees
G7C09 (B)
B. 90 degrees
What is an advantage of using I and Q signals in software-defined radios (SDRs)?
A. The need for high resolution analog-to-digital converters is eliminated
B. All types of modulation can be created with appropriate processing.
C. Minimum detectible signal level is reduced
D. Converting the signal from digital to analog creates mixing products
G7C10 (B)
B. All types of modulation can be created with appropriate processing.
What is meant by the term “software-defined radio” (SDR)?
A. A radio in which most major signal processing functions are performed by software
B. A radio that provides computer interface for automatic logging of band and frequency
C. A radio that uses crystal filters designed using software
D. A computer model that can simulate performance of a radio to aid in the design process
G7C11 (A)
A. A radio in which most major signal processing functions are performed by software
What is the frequency above which a low-pass filter’s output power is less than half the input power?
A. Notch frequency
B. Neper frequency
C. Cutoff frequency
D. Rolloff frequency
G7C12 (C)
C. Cutoff frequency
What term specifies a filter’s maximum ability to reject signals outside its passband?
A. Notch depth
B. Rolloff
C. Insertion loss
D. Ultimate rejection
G7C13 (D)
D. Ultimate rejection
The bandwidth of a band-pass filter is measured between what two frequencies?
A. Upper and lower half-power
B. Cutoff and rolloff
C. Pole and zero
D. Image and harmonic
G7C14 (A)
A. Upper and lower half-power
What term specifies a filter’s attenuation inside its passband?
A. Insertion loss
B. Return loss
C. Q
D. Ultimate rejection
G7C15 (A)
A. Insertion loss
Which of the following is a typical application for a Direct Digital Synthesizer?
A. A high-stability variable frequency oscillator in a transceiver
B. A digital voltmeter
C. A digital mode interface between a computer and a transceiver
D. A high-sensitivity radio direction finder
G7C16 (A)
A. A high-stability variable frequency oscillator in a transceiver
