2007 General Class Questions Pool

This pool is valid for Element 3 exams given on or after July 1, 2007]

SUBELEMENT G7 - PRACTICAL CIRCUITS
[2 Exam Questions -- 2 Groups]

G7A - Power supplies; transmitters and receivers; filters, schematic drawing symbols

G7A01
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

G7A02
What components are used in a power-supply filter network?
A. Diodes
B. Transformers and transistors
C. Quartz crystals
D. Capacitors and inductors

G7A03
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

G7A04
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

G7A05
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

G7A06
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

G7A07
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

G7A08
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

G7A09
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

G7A10
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

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

G7A12
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

G7A13
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

G7A14
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

G7A15
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

G7A16
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

G7A17
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

G7A18
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

G7A19
Which symbol in figure G7-1 represents a fixed resistor?
A. Symbol 2
B. Symbol 6
C. Symbol 3

D. Symbol 12

G7A20
Which symbol in figure G7-1 represents a single cell battery?
A. Symbol 5
B. Symbol 12
C. Symbol 8
D. Symbol 13

G7A21
Which symbol in figure G7-1 represents a NPN transistor?
A. Symbol 2
B. Symbol 4

C. Symbol 10
D. Symbol 12

G7A22
Which symbol in figure G7-1 represents a variable capacitor?
A. Symbol 2
B. Symbol 11
C. Symbol 5

D. Symbol 12

G7A23
Which symbol in figure G7-1 represents a transformer?
A. Symbol 6

B. Symbol 4
C. Symbol 10
D. symbol 2

G7A24
Which symbol in figure G7-1 represents a single pole switch?
A. Symbol 2
B. Symbol 3
C. Symbol 11

D. Symbol 12

G7B - Digital circuits (gates, flip-flops, shift registers); amplifiers and oscillators

G7B01
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

G7B02
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

G7B03
What is the output of a two-input NAND gate, given both inputs are “one”?
A. Two
B. One
C. Zero

D. Minus One

G7B04
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

G7B05
How many states are there in a 3-bit binary counter?
A. 3
B. 6
C. 8

D. 16

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

G7B07
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

G7B08
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

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

G7B10
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

G7B11
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

G7B12
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

G7B13
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

G7B14
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

Back

wx9j@att.net