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G7 – PRACTICAL CIRCUITS [3 Exam Questions – 3 Groups]

 

 

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G7A – Power supplies; schematic symbols

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G7A01

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

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G7A02

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

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G7A03

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

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G7A04

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

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G7A05

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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G7A06

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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G7A07

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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G7A08

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

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G7A09

Which symbol in figure G7-1 represents a field effect transistor?

A. Symbol 2

B. Symbol 5

C. Symbol 1

D. Symbol 4

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G7A10

Which symbol in figure G7-1 represents a Zener diode?

A. Symbol 4

B. Symbol 1

C. Symbol 11

D. Symbol 5

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G7A11

Which symbol in figure G7-1 represents an NPN junction transistor?

A. Symbol 1

B. Symbol 2

C. Symbol 7

D. Symbol 11

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G7A12

Which symbol in Figure G7-1 represents a solid core transformer?

A. Symbol 4

B. Symbol 7

C. Symbol 6

D. Symbol 1

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G7A13

Which symbol in Figure G7-1 represents a tapped inductor?

A. Symbol 7

B. Symbol 11

C. Symbol 6

D. Symbol 1

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G7B – Digital circuits; amplifiers and oscillators

 

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G7B01

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

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G7B02

Which of these classes of amplifiers has the highest efficiency?

A. Class A

B. Class B

C. Class AB

D. Class C

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G7B03

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

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G7B04

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

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G7B05

How many states does a 3-bit binary counter have?

A. 3

B. 6

C. 8

D. 16

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G7B06

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

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

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G7B08

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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G7B09

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

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

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G7B11

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

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G7C – Receivers and transmitters; filters; oscillators

 

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G7C01

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

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G7C02

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

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G7C03

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

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G7C04

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

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G7C05

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

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G7C06

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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G7C07

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

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G7C08

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

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G7C09

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

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G7C10

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

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G7C11

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

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G7C12

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

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G7C13

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

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G7C14

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

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G7C15

What term specifies a filter’s attenuation inside its passband?

A. Insertion loss

B. Return loss

C. Q

D. Ultimate rejection

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G7C16

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

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