E7D Oscillators: types, applications,
stability; voltage-regulator
circuits: discrete, integrated and switched mode
E7D01
(D)
What
are three major oscillator circuits often used in Amateur Radio equipment?
A. Taft, Pierce and negative feedback
B. Colpitts, Hartley and Taft
C. Taft, Hartley and Pierce
D. Colpitts, Hartley and
Pierce
E7D02
(C)
What
condition must exist for a circuit to oscillate?
A. It must have a gain of less than 1
B. It must be neutralized
C. It must have positive
feedback sufficient to overcome losses
D. It must have negative feedback sufficient to
cancel the input
E7D03
(A)
How is
the positive feedback coupled to the input in a Hartley oscillator?
A. Through a tapped coil
B. Through a capacitive divider
C. Through link coupling
D. Through a neutralizing capacitor
E7D04
(C)
How is
the positive feedback coupled to the input in a Colpitts oscillator?
A. Through a tapped coil
B. Through link coupling
C. Through a capacitive
divider
D. Through a neutralizing capacitor
E7D05
(D)
How is
the positive feedback coupled to the input in a Pierce oscillator?
A. Through a tapped coil
B. Through link coupling
C. Through a neutralizing capacitor
D. Through capacitive
coupling
E7D06
(B)
Which
type of oscillator circuits are commonly used in a VFO?
A. Pierce and Zener
B. Colpitts and Hartley
C. Armstrong and deForest
D. Negative feedback and Balanced feedback
E7D07
(B)
Why
must a very stable reference oscillator be used as part of a phase-locked loop
(PLL) frequency synthesizer?
A. Any amplitude variations in the reference
oscillator signal will prevent the loop from locking to the desired signal
B. Any phase variations in
the reference oscillator signal will produce phase noise in the synthesizer
output
C. Any phase variations in the reference
oscillator signal will produce harmonic distortion in the modulating signal
D. Any amplitude variations in the reference
oscillator signal will prevent the loop from changing frequency
E7D08
(D)
What is
one characteristic of a linear electronic voltage regulator?
A. It has a ramp voltage as its output
B. The pass transistor switches from the
"off" state to the "on" state
C. The control device is switched on or off,
with the duty cycle proportional to the line or load conditions
D. The conduction of a
control element is varied in direct proportion to the line voltage or load
current
E7D09
(C)
What is
one characteristic of a switching electronic voltage regulator?
A. The conduction of a control element is
varied in direct proportion to the line voltage or load current
B. It provides more than one output voltage
C. The control device is
switched on or off, with the duty cycle proportional to the line or load
conditions
D. It gives a ramp voltage at its output
E7D10
(A)
What
device is typically used as a stable reference voltage in a linear voltage
regulator?
A. A Zener diode
B. A tunnel diode
C. An SCR
D. A varactor diode
E7D11
(B)
What
type of linear regulator is used in applications requiring efficient utilization
of the primary power source?
A. A constant current source
B. A series regulator
C. A shunt regulator
D. A shunt current source
E7D12
(D)
What
type of linear voltage regulator is used in applications requiring a constant
load on the unregulated voltage source?
A. A constant current source
B. A series regulator
C. A shunt current source
D. A shunt regulator
E7D13
(C)
To
obtain the best temperature stability, approximately what operating voltage
should be used for the reference diode in a linear voltage regulator?
A. 2 volts
B. 3 volts
C. 6 volts
D. 10 volts
E7D14
(B)
What
are the important characteristics of a three-terminal regulator?
A. Maximum and minimum input voltage, minimum
output current and voltage
B. Maximum and minimum input
voltage, maximum output current and voltage
C. Maximum and minimum input voltage, minimum
output current and maximum output voltage
D. Maximum and minimum input voltage, minimum
output voltage and maximum output current
E7D15
(A)
What
type of voltage regulator limits the voltage drop across its junction when a
specified current passes through it in the reverse-breakdown direction?
A. A Zener diode
B. A three-terminal regulator
C. A bipolar regulator
D. A pass-transistor regulator
E7D16
(C)
What
type of voltage regulator contains a voltage reference, error amplifier,
sensing resistors and transistors, and a pass element in one package?
A. A switching regulator
B. A Zener regulator
C. A three-terminal
regulator
D. An op-amp regulator