SUBELEMENT G7 – PRACTICAL CIRCUITS [2 exam question – 2 groups]
G7A - Power supplies; transmitters and receivers; filters, schematic drawing symbols
G7A01 (B)
What safety feature does a power-supply bleeder resistor provide?
A. It acts as a fuse for excess voltage
B. It discharges the filter capacitors
C. It removes shock hazards from the induction coils
D. It eliminates ground-loop current
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G7A02 (D)
What components are used in a power-supply filter network?
A. Diodes
B. Transformers and transistors
C. Quartz crystals
D. Capacitors and inductors
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G7A03 (C)
What should be the minimum peak-inverse-voltage rating of the rectifier in a full-wave power supply?
A. One-quarter the normal output voltage of the power supply
B. Half the normal output voltage of the power supply
C. Double the normal peak output voltage of the power supply
D. Equal to the normal output voltage of the power supply
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G7A04 (D)
What should be the approximate minimum peak-inverse-voltage rating of the rectifier in a half-wave power supply?
A. One-half the normal peak output voltage of the power supply
B. Half the normal output voltage of the power supply
C. Equal to the normal output voltage of the power supply
D. Two times the normal peak output voltage of the power supply
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G7A05 (B)
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
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G7A06 (B)
Which of the following might be used to process signals from the balanced modulator and send them to the mixer in a single-sideband phone transmitter?
A. Carrier oscillator
B. Filter
C. IF amplifier
D. RF amplifier
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G7A07 (D)
Which circuit is used to combine signals from the carrier oscillator and speech amplifier and send the result to the filter in a typical single-sideband phone transmitter?
A. Mixer
B. Detector
C. IF amplifier
D. Balanced modulator
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G7A08 (C)
What circuit is used to process signals from the RF amplifier and local oscillator and send the result to the IF filter in a superheterodyne receiver?
A. Balanced modulator
B. IF amplifier
C. Mixer
D. Detector
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G7A09 (D)
What circuit is used to process signals from the IF amplifier and BFO and send the result to the AF amplifier in a single-sideband phone superheterodyne receiver?
A. RF oscillator
B. IF filter
C. Balanced modulator
D. Product detector
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G7A10 (A)
What is an advantage of a crystal controlled transmitter?
A. Stable output frequency
B. Excellent modulation clarity
C. Ease of switching between bands
D. Ease of changing frequency
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G7A11 (C)
What is the simplest combination of stages that can be combined to implement a superheterodyne receiver?
A. RF amplifier, detector, audio amplifier
B. RF amplifier, mixer, if amplifier
C. HF oscillator, mixer, detector
D. HF oscillator, product detector, audio amplifier
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G7A12 (D)
What type of receiver is suitable for CW and SSB reception but does not require a mixer stage or an IF amplifier?
A. A super-regenerative receiver
B. A TRF receiver
C. A super-heterodyne receiver
D. A direct conversion receiver
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G7A13 (D)
What type of circuit is used in many FM receivers to convert signals coming from the IF amplifier to audio?
A. Product detector
B. Phase inverter
C. Mixer
D. Discriminator
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G7A14 (A)
Which of the following is a desirable characteristic for capacitors used to filter the DC output of a switching power supply?
A. Low equivalent series resistance
B. High equivalent series resistance
C. Low Temperature coefficient
D. High Temperature coefficient
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G7A15 (C)
Which of the following is an advantage of a switched-mode 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 of these choices are correct
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G7A16(B)
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
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G7A17 (D)
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
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G7A18 (A)
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
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G7A19 (C)
Which symbol in figure G7-1 represents a fixed resistor?
A. Symbol 2
B. Symbol 6
C. Symbol 3
D. Symbol 12
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G7A20 (D)
Which symbol in figure G7-1 represents a single cell battery?
A. Symbol 5
B. Symbol 12
C. Symbol 8
D. Symbol 13
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G7A21 (B)
Which symbol in figure G7-1 represents a NPN transistor?
A. Symbol 2
B. Symbol 4
C. Symbol 10
D. Symbol 12
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G7A22 (C)
Which symbol in figure G7-1 represents a variable capacitor?
A. Symbol 2
B. Symbol 11
C. Symbol 5
D. Symbol 12
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G7A23 (A)
Which symbol in figure G7-1 represents a transformer?
A. Symbol 6
B. Symbol 4
C. Symbol 10
D. symbol 2
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G7A24 (C)
Which symbol in figure G7-1 represents a single pole switch?
A. Symbol 2
B. Symbol 3
C. Symbol 11
D. Symbol 12
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G7B - Digital circuits (gates, flip-flops, shift registers); amplifiers and oscillators
G7B01 (B)
Which of the following describes a “flip-flop” circuit?
A. A transmit-receive circuit
B. A digital circuit with two stable states
C. An RF limiter
D. A voice-operated switch
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G7B02 (A)
Why do digital circuits use the binary number system?
A. Binary "ones" and "zeros" are easy to represent with an "on" or "off" state
B. The binary number system is most accurate
C. Binary numbers are more compatible with analog circuitry
D. All of these answers are correct
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G7B03 (C)
What is the output of a two-input NAND gate, given both inputs are “one”?
A. Two
B. One
C. Zero
D. Minus One
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G7B04 (B)
What is the output of a NOR gate given that both inputs are “zero”?
A. Zero
B. One
C. Minus one
D. The opposite from the previous state
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G7B05 (C)
How many states are there in a 3-bit binary counter?
A. 3
B. 6
C. 8
D. 16
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G7B06 (A)
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
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G7B07 (D)
What are the basic components of virtually all oscillators?
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
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G7B08 (C)
What determines the frequency of an RC oscillator?
A. The ratio of the capacitors in the feedback loop
B. The value of the inductor in the tank circuit
C. The phase shift of the RC feedback circuit
D. The gain of the amplifier
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G7B09 (C)
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
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G7B10 (D)
Which of the following is a characteristic of a Class A amplifier?
A. Low standby power
B. High Efficiency
C. No need for bias
D. Low distortion
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G7B11 (B)
For which of the following modes is a Class C power stage appropriate for amplifying a modulated signal?
A. SSB
B. CW
C. AM
D. All of these answers are correct
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G7B12 (A)
Which of the following is an advantage of a Class C amplifier?
A. High efficiency
B. Linear operation
C. No need for tuned circuits
D. All of these answers are correct
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G7B13 (B)
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
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G7B14 (B)
Which of the following describes a linear amplifier?
A. Any RF power amplifier used in conjunction with an amateur transceiver
B. An amplifier whose output preserves the input waveform
C. A Class C high efficiency amplifier
D. An amplifier used as a frequency multiplier
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