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SUBELEMENT G7 -- PRACTICAL CIRCUITS [1 exam question -- 1 group]

G7A Power supplies and filters; single-sideband transmitters and receivers

G7A01 (B)
What safety feature does a power-supply bleeder resistor provide?
A. It does not affect voltage regulation
B. It discharges the filter capacitors
C. It removes shock hazards from the induction coils
D. It eliminates ground-loop current

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

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

G7A04 (D)
What should be the minimum peak-inverse-voltage rating of 
the rectifier in a half-wave power supply?
A.   One-quarter to 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.   One to two times the normal peak output voltage of the 
power supply

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

G7A06 (B)
In a typical single-sideband phone transmitter, what 
circuit processes signals from the balanced modulator and 
sends signals to the mixer?
A.   Carrier oscillator
B.   Filter
C.   IF amplifier
D.   RF amplifier

G7A07 (D)
In a single-sideband phone transmitter, what circuit 
processes signals from the carrier oscillator and the 
speech amplifier and sends signals to the filter?
A.   Mixer
B.   Detector
C.   IF amplifier
D.   Balanced modulator

G7A08 (C)
In a single-sideband phone superheterodyne receiver, what 
circuit processes signals from the RF amplifier and the 
local oscillator and sends signals to the IF filter?
A.   Balanced modulator
B.   IF amplifier
C.   Mixer
D.   Detector

G7A09 (D)
In a single-sideband phone superheterodyne receiver, what 
circuit processes signals from the IF amplifier and the BFO 
and sends signals to the AF amplifier?
A.   RF oscillator
B.   IF filter
C.   Balanced modulator
D.   Detector

G7A10 (A)
What type of power supply circuit is often used to provide 
overvoltage protection at its output?
A.   Crowbar
B.   Circuit breaker
C.   Ferrite transformer
D.   Buck-out transistor

G7A11 (A)
What type of capacitors should be used to filter the 
rectified DC output of a switching power supply?
A.   Capacitors with low equivalent series resistance
B.   Ordinary, large value electrolytic capacitors
C.   NPO-type ceramic disc or silver mica capacitors
D.   Capacitors with high equivalent series inductance

G7A12 (C)
Which of the following is an advantage of a switched-mode 
power supply as compared to a linear power supply?
A.   Higher output voltages are possible with the switched-
mode supply
B.   Fewer circuit components are required for the 
switched-mode supply
C.   The relatively high frequency power oscillator allows 
the use of small, lightweight and low-cost transformers in 
the switched-mode supply
D.   All of these choices are correct

G7A13 (A)
In a switched-mode power supply, what is the first step in 
converting the 120 volt AC input voltage to a 12 volt DC 
output voltage?
A.   The 120 volt AC is first rectified and filtered
B.   The 120 volt AC is first converted to 12 volt AC with 
a transformer
C.   The 120 volt AC is switched off when the waveform 
exceeds 12 volts, and is switched on again when the 
waveform drops below 12 volts
D.   An AC clamp is used to limit the input signal to no 
more than 20 volts DC


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