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139 Cards in this Set
- Front
- Back
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1] What is a linear electronic voltage regulator?
a} A regulator that has a ramp voltage as its output. b} A regulator in which the pass transistor switches from the "off" state to the "on" state. c} A regulator in which the control device is switched on or off, with the duty cycle proportional to the line or load conditions. d} A regulator in which the conduction of a control element is varied in direct proportion to the line voltage or load current. |
d} A regulator in which the conduction of a control element is
varied in direct proportion to the line voltage or load current. |
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2] What is a switching electronic voltage regulator?
a} A regulator in which the conduction of a control element is varied in direct proportion to the line voltage or load current. b} A regulator that provides more than one output voltage. c} A regulator in which the control device is switched on or off, with the duty cycle proportional to the line or load conditions. d} A regulator that gives a ramp voltage at its output. |
c} A regulator in which the control device is switched on or
off, with the duty cycle proportional to the line or load conditions. |
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3] What device is usually 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. |
a} A Zener diode.
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4] 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. |
b} A series regulator.
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5] What type of linear voltage regulator is used in
applications where the load on the unregulated voltage source must be kept constant? a} A constant current source. b} A series regulator. c} A shunt current source. d} A shunt regulator. |
d} A shunt regulator.
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6] To obtain the best temperature stability, what should be
the operating voltage of the reference diode in a linear voltage regulator? a} Approximately 2.0 volts. b} Approximately 3.0 volts. c} Approximately 6.0 volts. d} Approximately 10.0 volts. |
c} Approximately 6.0 volts.
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7] What is the meaning of the term remote sensing with regard
to a linear voltage regulator? a} The feedback connection to the error amplifier is made directly to the load. b} Sensing is accomplished by wireless inductive loops. c} The load connection is made outside the feedback loop. d} The error amplifier compares the input voltage to the reference voltage. |
a} The feedback connection to the error amplifier is made
directly to the load. |
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8] What is a three-terminal regulator?
a} A regulator that supplies three voltages with variable current. b} A regulator that supplies three voltages at a constant current. c} A regulator containing three error amplifiers and sensing transistors. d} A regulator containing a voltage reference, error amplifier, sensing resistors and transistors, and a pass element. |
d} A regulator containing a voltage reference, error amplifier,
sensing resistors and transistors, and a pass element. |
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9] 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. |
b} Maximum and minimum input voltage, maximum output current and
voltage. |
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10] What is the distinguishing feature of a Class A amplifier?
a} Output for less than 180 degrees of the signal cycle. b} Output for the entire 360 degrees of the signal cycle. c} Output for more than 180 degrees and less than 360 degrees of the signal cycle. d} Output for exactly 180 degrees of the input signal cycle. |
b} Output for the entire 360 degrees of the signal cycle.
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11] What class of amplifier is distinguished by the presence
of output throughout the entire signal cycle and the input never goes into the cutoff region? a} Class A. b} Class B. c} Class C. d} Class D. |
a} Class A.
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12] What is the distinguishing characteristic of a Class B
amplifier? a} Output for the entire input signal cycle. b} Output for greater than 180 degrees and less than 360 degrees of the input signal cycle. c} Output for less than 180 degrees of the input signal cycle. d} Output for 180 degrees of the input signal cycle. |
d} Output for 180 degrees of the input signal cycle.
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13] What class of amplifier is distinguished by the flow of
current in the output essentially in 180 degree pulses? a} Class A. b} Class B. c} Class C. d} Class D. |
b} Class B.
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14] What is a Class AB amplifier?
a} Output is present for more than 180 degrees but less than 360 degrees of the signal input cycle. b} Output is present for exactly 180 degrees of the input signal cycle. c} Output is present for the entire input signal cycle. d} Output is present for less than 180 degrees of the input signal cycle. |
a} Output is present for more than 180 degrees but less than 360
degrees of the signal input cycle. |
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15] What is the distinguishing feature of a Class C amplifier?
a} Output is present for less than 180 degrees of the input signal cycle. b} Output is present for exactly 180 degrees of the input signal cycle. c} Output is present for the entire input signal cycle. d} Output is present for more than 180 degrees but less than 360 degrees of the input signal cycle. |
a} Output is present for less than 180 degrees of the input
signal cycle. |
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16] What class of amplifier is distinguished by the bias being
set well beyond cutoff? a} Class A. b} Class B. c} Class C. d} Class AB. |
c} Class C.
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17] Which class of amplifier provides the highest efficiency?
a} Class A. b} Class B. c} Class C. d} Class AB. |
c} Class C.
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18] Which class of amplifier has the highest linearity and
least distortion? a} Class A. b} Class B. c} Class C. d} Class AB. |
a} Class A.
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19] Which class of amplifier has an operating angle of more
than 180 degrees but less than 360 degrees when driven by a sine wave signal? a} Class A. b} Class B. c} Class C. d} Class AB. |
d} Class AB.
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20] What is an L-network?
a} A network consisting entirely of four inductors. b} A network consisting of an inductor and a capacitor. c} A network used to generate a leading phase angle. d} A network used to generate a lagging phase angle. |
b} A network consisting of an inductor and a capacitor.
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21] What is a pi-network?
a} A network consisting entirely of four inductors or four capacitors. b} A Power Incidence network. c} An antenna matching network that is isolated from ground. d} A network consisting of one inductor and two capacitors or two inductors and one capacitor. |
d} A network consisting of one inductor and two capacitors or
two inductors and one capacitor. |
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22] What is a pi-L-network?
a} A Phase Inverter Load network. b} A network consisting of two inductors and two capacitors. c} A network with only three discrete parts. d} A matching network in which all components are isolated from ground. |
b} A network consisting of two inductors and two capacitors.
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23] Which network provides the greatest harmonic suppression?
a} L-network. b} Pi-network. c} Inverse L-network. d} Pi-L-network. |
d} Pi-L-network.
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24] What are the three most commonly used networks to
accomplish a match between an amplifying device and a transmission line? a} M-network, pi-network and T-network. b} T-network, M-network and Q-network. c} L-network, pi-network and pi-L-network. d} L-network, M-network and C-network. |
c} L-network, pi-network and pi-L-network.
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25] How are networks able to transform one impedance to
another? a} Resistances in the networks substitute for resistances in the load. b} The matching network introduces negative resistance to cancel the resistive part of an impedance. c} The matching network introduces transconductance to cancel the reactive part of an impedance. d} The matching network can cancel the reactive part of an impedance and change the value of the resistive part of an impedance. |
d} The matching network can cancel the reactive part of an
impedance and change the value of the resistive part of an impedance. |
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26] Which type of network offers the greater transformation
ratio? a} L-network. b} Pi-network. c} Constant-K. d} Constant-M. |
b} Pi-network.
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27] Why is the L-network of limited utility in impedance
matching? a} It matches a small impedance range. b} It has limited power handling capabilities. c} It is thermally unstable. d} It is prone to self resonance. |
a} It matches a small impedance range.
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28] What is an advantage of using a pi-L-network instead of a
pi-network for impedance matching between the final amplifier of a vacuum-tube type transmitter and a multiband antenna? a} Greater transformation range. b} Higher efficiency. c} Lower losses. d} Greater harmonic suppression. |
d} Greater harmonic suppression.
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29] Which type of network provides the greatest harmonic
suppression? a} L-network. b} Pi-network. c} Pi-L-network. d} Inverse-Pi network. |
c} Pi-L-network.
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30] What are the three general groupings of filters?
a} High-pass, low-pass and band-pass. b} Inductive, capacitive and resistive. c} Audio, radio and capacitive. d} Hartley, Colpitts and Pierce. |
a} High-pass, low-pass and band-pass.
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31] What is a constant-K filter?
a} A filter that uses Boltzmann's constant. b} A filter whose velocity factor is constant over a wide range of frequencies. c} A filter whose product of the series- and shunt-element impedances is a constant for all frequencies. d} A filter whose input impedance varies widely over the design bandwidth. |
c} A filter whose product of the series- and shunt-element
impedances is a constant for all frequencies. |
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32] What is an advantage of a constant-k filter?
a} It has high attenuation for signals on frequencies far removed from the passband. b} It can match impedances over a wide range of frequencies. c} It uses elliptic functions. d} The ratio of the cutoff frequency to the trap frequency can be varied. |
a} It has high attenuation for signals on frequencies far
removed from the passband. |
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33] What is an m-derived filter?
a} A filter whose input impedance varies widely over the design bandwidth. b} A filter whose product of the series- and shunt-element impedances is a constant for all frequencies. c} A filter whose schematic shape is the letter "M". d} A filter that uses a trap to attenuate undesired frequencies too near cutoff for a constant-k filter. |
d} A filter that uses a trap to attenuate undesired frequencies
too near cutoff for a constant-k filter. |
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34] What are the distinguishing features of a Butterworth
filter? a} A filter whose product of the series- and shunt-element impedances is a constant for all frequencies. b} It only requires capacitors. c} It has a maximally flat response over its passband. d} It requires only inductors. |
c} It has a maximally flat response over its passband.
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35] What are the distinguishing features of a Chebyshev
filter? a} It has a maximally flat response over its passband. b} It allows ripple in the passband. c} It only requires inductors. d} A filter whose product of the series- and shunt-element impedances is a constant for all frequencies. |
b} It allows ripple in the passband.
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36] When would it be more desirable to use an m-derived filter
over a constant-k filter? a} When the response must be maximally flat at one frequency. b} When you need more attenuation at a certain frequency that is too close to the cut-off frequency for a constant-k filter. c} When the number of components must be minimized. d} When high power levels must be filtered. |
b} When you need more attenuation at a certain frequency that is
too close to the cut-off frequency for a constant-k filter. |
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37] What are three major oscillator circuits often used in
radio equipment? a} Taft, Pierce, and negative feedback. b} Colpitts, Hartley, and Taft. c} Taft, Hartley, and Pierce. d} Colpitts, Hartley, and Pierce. |
d} Colpitts, Hartley, and Pierce.
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38] How is the positive feedback coupled to the input in a
Hartley oscillator? a} Through a neutralizing capacitor. b} Through a capacitive divider. c} Through link coupling. d} Through a tapped coil. |
d} Through a tapped coil.
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39] 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. |
c} Through a capacitive divider.
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40] 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 capacitive divider. d} Through capacitive coupling. |
d} Through capacitive coupling.
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41] Which of the three major oscillator circuits used in radio
equipment utilizes a quartz crystal? a} Negative feedback. b} Hartley. c} Colpitts. d} Pierce. |
d} Pierce.
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42] What is the piezoelectric effect?
a} Mechanical vibration of a crystal by the application of a voltage. b} Mechanical deformation of a crystal by the application of a magnetic field. c} The generation of electrical energy by the application of light. d} Reversed conduction states when a P-N junction is exposed to light. |
a} Mechanical vibration of a crystal by the application of a
voltage. |
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43] What is the major advantage of a Pierce oscillator?
a} It is easy to neutralize. b} It doesn't require an LC tank circuit. c} It can be tuned over a wide range. d} It has a high output power. |
b} It doesn't require an LC tank circuit.
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44] Which type of oscillator circuit is commonly used in a
VFO? a} Pierce. b} Colpitts. c} Hartley. d} Negative feedback. |
b} Colpitts.
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45] Why is the Colpitts oscillator circuit commonly used in a
VFO? a} The frequency is a linear function of the load impedance. b} It can be used with or without crystal lock-in. c} It is stable. d} It has high output power. |
c} It is stable.
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46] What is meant by the term: modulation?
a} The squelching of a signal until a critical signal-to-noise ratio is reached. b} Carrier rejection through phase nulling. c} A linear amplification mode. d} A mixing process whereby information is imposed upon a carrier. |
d} A mixing process whereby information is imposed upon a
carrier. |
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47] How is a G3E FM-phone emission produced?
a} With a balanced modulator on the audio amplifier. b} With a reactance modulator on the oscillator. c} With a reactance modulator on the final amplifier. d} With a balanced modulator on the oscillator. |
b} With a reactance modulator on the oscillator.
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48] What is a reactance modulator?
a} A circuit that acts as a variable resistance or capacitance to produce FM signals. b} A circuit that acts as a variable resistance or capacitance to produce AM signals. c} A circuit that acts as a variable inductance or capacitance to produce FM signals. d} A circuit that acts as a variable inductance or capacitance to produce AM signals. |
c} A circuit that acts as a variable inductance or capacitance
to produce FM signals. |
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49] What is a balanced modulator?
a} An FM modulator that produces a balanced deviation. b} A modulator that produces a double sideband, suppressed carrier signal. c} A modulator that produces a single sideband, suppressed carrier signal. d} A modulator that produces a full carrier signal. |
b} A modulator that produces a double sideband, suppressed
carrier signal. |
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50] How can a single-sideband phone signal be generated?
a} By driving a product detector with a DSB signal. b} By using a reactance modulator followed by a mixer. c} By using a loop modulator followed by a mixer. d} By using a balanced modulator followed by a filter. |
d} By using a balanced modulator followed by a filter.
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51] How can a double-sideband phone signal be generated?
a} By feeding a phase modulated signal into a low pass filter. b} By using a balanced modulator followed by a filter. c} By detuning a Hartley oscillator. d} By modulating the plate voltage of a class C amplifier. |
d} By modulating the plate voltage of a class C amplifier.
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52] How is the efficiency of a power amplifier determined?
a} Efficiency = ( RF power out / DC power in ) X 100%. b} Efficiency = ( RF power in / RF power out ) X 100%. c} Efficiency = ( RF power in / DC power in ) X 100%. d} Efficiency = ( DC power in / RF power in ) X 100%. |
a} Efficiency = ( RF power out / DC power in ) X 100%.
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53] For reasonably efficient operation of a transistor
amplifier, what should the load resistance be with 12 volts at the collector and 5 watts power output? a} 100.3 ohms. b} 14.4 ohms. c} 10.3 ohms. d} 144 ohms. |
b} 14.4 ohms.
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54] What is the flywheel effect?
a} The continued motion of a radio wave through space when the transmitter is turned off. b} The back and forth oscillation of electrons in an LC circuit. c} The use of a capacitor in a power supply to filter rectified AC. d} The transmission of a radio signal to a distant station by several hops through the ionosphere. |
b} The back and forth oscillation of electrons in an LC
circuit. |
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55] What order of Q is required by a tank-circuit sufficient
to reduce harmonics to an acceptable level? a} Approximately 120. b} Approximately 12. c} Approximately 1200. d} Approximately 1.2. |
b} Approximately 12.
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56] How can parasitic oscillations be eliminated from a power
amplifier? a} By tuning for maximum SWR. b} By tuning for maximum power output. c} By neutralization. d} By tuning the output. |
c} By neutralization.
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57] What is the process of detection?
a} The process of masking out the intelligence on a received carrier to make an S-meter operational. b} The recovery of intelligence from the modulated RF signal. c} The modulation of a carrier. d} The mixing of noise with the received signal. |
b} The recovery of intelligence from the modulated RF signal.
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58] What is the principle of detection in a diode detector?
a} Rectification and filtering of RF. b} Breakdown of the Zener voltage. c} Mixing with noise in the transition region of the diode. d} The change of reactance in the diode with respect to frequency. |
a} Rectification and filtering of RF.
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59] What is a product detector?
a} A detector that provides local oscillations for input to the mixer. b} A detector that amplifies and narrows the band-pass frequencies. c} A detector that uses a mixing process with a locally generated carrier. d} A detector used to detect cross-modulation products. |
c} A detector that uses a mixing process with a locally
generated carrier. |
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60] How are FM-phone signals detected?
a} By a balanced modulator. b} By a frequency discriminator. c} By a product detector. d} By a phase splitter. |
b} By a frequency discriminator.
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61] What is a frequency discriminator?
a} A circuit for detecting FM signals. b} A circuit for filtering two closely adjacent signals. c} An automatic bandswitching circuit. d} An FM generator. |
a} A circuit for detecting FM signals.
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62] What is the mixing process?
a} The elimination of noise in a wideband receiver by phase comparison. b} The elimination of noise in a wideband receiver by phase differentiation. c} Distortion caused by auroral propagation. d} The combination of two signals to produce sum and difference frequencies. |
d} The combination of two signals to produce sum and difference
frequencies. |
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63] What are the principal frequencies that appear at the
output of a mixer circuit? a} Two and four times the original frequency. b} The sum, difference and square root of the input frequencies. c} The original frequencies and the sum and difference frequencies. d} 1.414 and 0.707 times the input frequency. |
c} The original frequencies and the sum and difference
frequencies. |
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64] What are the advantages of the frequency-conversion
process? a} Automatic squelching and increased selectivity. b} Increased selectivity and optimal tuned-circuit design. c} Automatic soft limiting and automatic squelching. d} Automatic detection in the RF amplifier and increased selectivity. |
b} Increased selectivity and optimal tuned-circuit design.
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65] What occurs in a receiver when an excessive amount of
signal energy reaches the mixer circuit? a} Spurious mixer products are generated. b} Mixer blanking occurs. c} Automatic limiting occurs. d} A beat frequency is generated. |
a} Spurious mixer products are generated.
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66] How much gain should be used in the RF amplifier stage of
a receiver? a} As much gain as possible short of self oscillation. b} Sufficient gain to allow weak signals to overcome noise generated in the first mixer stage. c} Sufficient gain to keep weak signals below the noise of the first mixer stage. d} It depends on the amplification factor of the first IF stage. |
b} Sufficient gain to allow weak signals to overcome noise
generated in the first mixer stage. |
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67] Why should the RF amplifier stage of a receiver only have
sufficient gain to allow weak signals to overcome noise generated in the first mixer stage? a} To prevent the sum and difference frequencies from being generated. b} To prevent bleed-through of the desired signal. c} To prevent the generation of spurious mixer products. d} To prevent bleed-through of the local oscillator. |
c} To prevent the generation of spurious mixer products.
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68] What is the primary purpose of an RF amplifier in a
receiver? a} To provide most of the receiver gain. b} To vary the receiver image rejection by utilizing the AGC. c} To improve the receiver's noise figure. d} To develop the AGC voltage. |
c} To improve the receiver's noise figure.
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69] What is an i-f amplifier stage?
a} A fixed-tuned pass-band amplifier. b} A receiver demodulator. c} A receiver filter. d} A buffer oscillator. |
a} A fixed-tuned pass-band amplifier.
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70] What factors should be considered when selecting an
intermediate frequency? a} Cross-modulation distortion and interference. b} Interference to other services. c} Image rejection and selectivity. d} Noise figure and distortion. |
c} Image rejection and selectivity.
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71] What is the primary purpose of the first i-f amplifier
stage in a receiver? a} Noise figure performance. b} Tune out cross-modulation distortion. c} Dynamic response. d} Selectivity. |
d} Selectivity.
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72] What is the primary purpose of the final i-f amplifier
stage in a receiver? a} Dynamic response. b} Gain. c} Noise figure performance. d} Bypass undesired signals. |
b} Gain.
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73] What is a flip-flop circuit?
a} A binary sequential logic element with one stable state. b} A binary sequential logic element with eight stable states. c} A binary sequential logic element with four stable states. d} A binary sequential logic element with two stable states. |
d} A binary sequential logic element with two stable states.
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74] How many bits of information can be stored in a single
flip-flop circuit? a} 1. b} 2. c} 3. d} 4. |
a} 1.
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75] What is a bistable multivibrator circuit?
a} An "AND" gate. b} An "OR" gate. c} A flip-flop. d} A clock. |
c} A flip-flop.
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76] How many output changes are obtained for every two trigger
pulses applied to the input of a bistable T flip-flop circuit? a} No output level changes. b} One output level change. c} Two output level changes. d} Four output level changes. |
c} Two output level changes.
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77] The frequency of an AC signal can be divided
electronically by what type of digital circuit? a} A free-running multivibrator. b} An OR gate. c} A bistable multivibrator. d} An astable multivibrator. |
c} A bistable multivibrator.
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78] What type of digital IC is also known as a latch?
a} A decade counter. b} An OR gate. c} A flip-flop. d} An op-amp. |
c} A flip-flop.
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79] How many flip-flops are required to divide a signal
frequency by 4? a} 1. b} 2. c} 4. d} 8. |
b} 2.
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80] What is an astable multivibrator?
a} A circuit that alternates between two stable states. b} A circuit that alternates between a stable state and an unstable state. c} A circuit set to block either a 0 pulse or a 1 pulse and pass the other. d} A circuit that alternates between two unstable states. |
d} A circuit that alternates between two unstable states.
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81] What is a monostable multivibrator?
a} A circuit that can be switched momentarily to the opposite binary state and then returns after a set time to its original state. b} A "clock" circuit that produces a continuous square wave oscillating between 1 and 0. c} A circuit designed to store one bit of data in either the 0 or the 1 configuration. d} A circuit that maintains a constant output voltage, regardless of variations in the input voltage. |
a} A circuit that can be switched momentarily to the opposite
binary state and then returns after a set time to its original state. |
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82] What is an AND gate?
a} A circuit that produces a logic "1" at its output only if all inputs are logic "1". b} A circuit that produces a logic "0" at its output only if all inputs are logic "1". c} A circuit that produces a logic "1" at its output if only one input is a logic "1". d} A circuit that produces a logic "1" at its output if all inputs are logic "0". |
a} A circuit that produces a logic "1" at its output only if all
inputs are logic "1". |
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83] What is a NAND gate?
a} A circuit that produces a logic "0" at its output only when all inputs are logic "0". b} A circuit that produces a logic "1" at its output only when all inputs are logic "1". c} A circuit that produces a logic "0" at its output if some but not all of its inputs are logic "1". d} A circuit that produces a logic "0" at its output only when all inputs are logic "1". |
d} A circuit that produces a logic "0" at its output only when
all inputs are logic "1". |
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84] What is an OR gate?
a} A circuit that produces a logic "1" at its output if any input is logic "1". b} A circuit that produces a logic "0" at its output if any input is logic "1". c} A circuit that produces a logic "0" at its output if all inputs are logic "1". d} A circuit that produces a logic "1" at its output if all inputs are logic "0". |
a} A circuit that produces a logic "1" at its output if any
input is logic "1". |
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85] What is a NOR gate?
a} A circuit that produces a logic "0" at its output only if all inputs are logic "0". b} A circuit that produces a logic "1" at its output only if all inputs are logic "1". c} A circuit that produces a logic "0" at its output if any or all inputs are logic "1". d} A circuit that produces a logic "1" at its output if some but not all of its inputs are logic "1". |
c} A circuit that produces a logic "0" at its output if any or
all inputs are logic "1". |
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86] What is a NOT gate?
a} A circuit that produces a logic "O" at its output when the input is logic "1" and vice versa. b} A circuit that does not allow data transmission when its input is high. c} A circuit that allows data transmission only when its input is high. d} A circuit that produces a logic "1" at its output when the input is logic "1" and vice versa. |
a} A circuit that produces a logic "O" at its output when the
input is logic "1" and vice versa. |
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87] What is a truth table?
a} A table of logic symbols that indicate the high logic states of an op-amp. b} A diagram showing logic states when the digital device's output is true. c} A list of input combinations and their corresponding outputs that characterizes a digital device's function. d} A table of logic symbols that indicates the low logic states of an op-amp. |
c} A list of input combinations and their corresponding outputs
that characterizes a digital device's function. |
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88] In a positive-logic circuit, what level is used to
represent a logic 1? a} A low level. b} A positive-transition level. c} A negative-transition level. d} A high level. |
d} A high level.
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89] In a positive-logic circuit, what level is used to
represent a logic 0? a} A low level. b} A positive-transition level. c} A negative-transition level. d} A high level. |
a} A low level.
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90] In a negative-logic circuit, what level is used to
represent a logic 1? a} A low level. b} A positive-transition level. c} A negative-transition level. d} A high level. |
a} A low level.
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91] In a negative-logic circuit, what level is used to
represent a logic 0? a} A low level. b} A positive-transition level. c} A negative-transition level. d} A high level. |
d} A high level.
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92] What is a crystal-controlled marker generator?
a} A low-stability oscillator that "sweeps" through a band of frequencies. b} An oscillator often used in aircraft to determine the craft's location relative to the inner and outer markers at airports. c} A high-stability oscillator whose output frequency and amplitude can be varied over a wide range. d} A high-stability oscillator that generates a series of reference signals at known frequency intervals. |
d} A high-stability oscillator that generates a series of
reference signals at known frequency intervals. |
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93] What additional circuitry is required in a 100-kHz
crystal-controlled marker generator to provide markers at 50 and 25 kHz? a} An emitter-follower. b} Two frequency multipliers. c} Two flip-flops. d} A voltage divider. |
c} Two flip-flops.
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94] What is the purpose of a prescaler circuit?
a} It converts the output of a JK flip-flop to that of an RS flip-flop. b} It multiplies an HF signal so a low-frequency counter can display the operating frequency. c} It prevents oscillation in a low frequency counter circuit. d} It divides an HF signal so a low-frequency counter can display the operating frequency. |
d} It divides an HF signal so a low-frequency counter can
display the operating frequency. |
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95] What does the accuracy of a frequency counter depend on?
a} The internal crystal reference. b} A voltage-regulated power supply with an unvarying output. c} Accuracy of the AC input frequency to the power supply. d} Proper balancing of the power-supply diodes. |
a} The internal crystal reference.
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96] How many states does a decade counter digital IC have?
a} 6. b} 10. c} 15. d} 20. |
b} 10.
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97] What is the function of a decade counter digital IC?
a} Decode a decimal number for display on a seven-segment LED display. b} Produce one output pulse for every ten input pulses. c} Produce ten output pulses for every input pulse. d} Add two decimal numbers. |
b} Produce one output pulse for every ten input pulses.
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98] What are the advantages of using an op-amp instead of LC
elements in an audio filter? a} Op-amps are more rugged and can withstand more abuse than can LC elements. b} Op-amps are fixed at one frequency. c} Op-amps are available in more styles and types than are LC elements. d} Op-amps exhibit gain rather than insertion loss. |
d} Op-amps exhibit gain rather than insertion loss.
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99] What determines the gain and frequency characteristics of
an op-amp RC active filter? a} Values of capacitances and resistances built into the op-amp. b} Values of capacitances and resistances external to the op-amp. c} Voltage and frequency of DC input to the op-amp power supply. d} Regulated DC voltage output from the op-amp power supply. |
b} Values of capacitances and resistances external to the
op-amp. |
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100] What are the principle uses of an op-amp RC active
filter? a} Op-amp circuits are used as high-pass filters to block RFI at the input to receivers. b} Op-amp circuits are used as low-pass filters between transmitters and transmission lines. c} Op-amp circuits are used as filters for smoothing power-supply output. d} Op-amp circuits are used as audio filters for receivers. |
d} Op-amp circuits are used as audio filters for receivers.
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101] What type of capacitors should be used in an op-amp RC
active filter circuit? a} Electrolytic. b} Disc ceramic. c} Polystyrene. d} Paper dielectric. |
c} Polystyrene.
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102] How can unwanted ringing and audio instability be
prevented in a multisection op-amp RC audio filter circuit? a} Restrict both gain and Q. b} Restrict gain, but increase Q. c} Restrict Q, but increase gain. d} Increase both gain and Q. |
a} Restrict both gain and Q.
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103] Where should an op-amp RC active audio filter be placed
in a receiver? a} In the IF strip, immediately before the detector. b} In the audio circuitry immediately before the speaker or phone jack. c} Between the balanced modulator and frequency multiplier. d} In the low-level audio stages. |
d} In the low-level audio stages.
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104] What parameter must be selected when designing an audio
filter using an op-amp? a} Bandpass characteristics. b} Desired current gain. c} Temperature coefficient. d} Output-offset overshoot. |
a} Bandpass characteristics.
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105] What two factors determine the sensitivity of a receiver?
a} Dynamic range and third-order intercept. b} Cost and availability. c} Intermodulation distortion and dynamic range. d} Bandwidth and noise figure. |
d} Bandwidth and noise figure.
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106] What is the limiting condition for sensitivity in a
communications receiver? a} The noise floor of the receiver. b} The power-supply output ripple. c} The two-tone intermodulation distortion. d} The input impedance to the detector. |
a} The noise floor of the receiver.
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107] What is the theoretical minimum noise floor of a receiver
with a 400-hertz bandwidth? a} -141 dBm. b} -148 dBm. c} -174 dBm. d} -180 dBm. |
b} -148 dBm.
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108] How can selectivity be achieved in the front-end
circuitry of a communications receiver? a} By using an audio filter. b} By using a preselector. c} By using an additional RF amplifier stage. d} By using an additional IF amplifier stage. |
b} By using a preselector.
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109] A receiver selectivity of 2.4 kHz in the IF circuitry is
optimum for what type of signals? a} CW. b} SSB voice. c} Double-sideband AM voice. d} FSK RTTY. |
b} SSB voice.
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110] What occurs during CW reception if too narrow a filter
bandwidth is used in the IF stage of a receiver? a} Undesired signals will reach the audio stage. b} Output-offset overshoot. c} Cross-modulation distortion. d} Filter ringing. |
d} Filter ringing.
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111] (Refer to figure EL3F1) To find the supply power with
only a voltmeter, measure between: a} Z to W voltage times 150,000 divided by 2000. b} Y to Z voltage squared divided by 2000. c} W to Y voltage divided by 150. d} W to X voltage divided by 150,000 times W to Z voltage. |
d} W to X voltage divided by 150,000 times W to Z voltage.
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112] A receiver selectivity of 10 kHz in the IF circuitry is
optimum for what type of signals? a} SSB voice. b} Double-sideband AM. c} CW. d} FSK RTTY. |
b} Double-sideband AM.
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113] What degree of selectivity is desirable in the IF
circuitry of a single-sideband phone receiver? a} 1 kHz. b} 2.4 kHz. c} 4.2 kHz. d} 4.8 kHz. |
b} 2.4 kHz.
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114] What is an undesirable effect of using too wide a filter
bandwidth in the IF section of a receiver? a} Output-offset overshoot. b} Undesired signals will reach the audio stage. c} Thermal-noise distortion. d} Filter ringing. |
b} Undesired signals will reach the audio stage.
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115] How should the filter bandwidth of a receiver IF section
compare with the bandwidth of a received signal? a} Filter bandwidth should be slightly greater than the received-signal bandwidth. b} Filter bandwidth should be approximately half the received-signal bandwidth. c} Filter bandwidth should be approximately two times the received-signal bandwidth. d} Filter bandwidth should be approximately four times the received-signal bandwidth. |
a} Filter bandwidth should be slightly greater than the
received-signal bandwidth. |
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116] What degree of selectivity is desirable in the IF
circuitry of an FM-phone receiver? a} 1 kHz. b} 2.4 kHz. c} 4.2 kHz. d} 15 kHz. |
d} 15 kHz.
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117] How can selectivity be achieved in the IF circuitry of a
communications receiver? a} Incorporate a means of varying the supply voltage to the local oscillator circuitry. b} Replace the standard JFET mixer with a bipolar transistor followed by a capacitor of the proper value. c} Remove AGC action from the IF stage and confine it to the audio stage only. d} Incorporate a high-Q filter. |
d} Incorporate a high-Q filter.
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118] What is meant by the dynamic range of a communications
receiver? a} The number of kHz between the lowest and the highest frequency to which the receiver can be tuned. b} The maximum possible undistorted audio output of the receiver, referenced to one milliwatt. c} The ratio between the minimum discernible signal and the largest tolerable signal without causing audible distortion products. d} The difference between the lowest-frequency signal and the highest-frequency signal detectable without moving the tuning knob. |
c} The ratio between the minimum discernible signal and the
largest tolerable signal without causing audible distortion products. |
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119] What is the term for the ratio between the largest
tolerable receiver input signal and the minimum discernible signal? a} Intermodulation distortion. b} Noise floor. c} Noise figure. d} Dynamic range. |
d} Dynamic range.
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120] What type of problems are caused by poor dynamic range in
a communications receiver? a} Cross-modulation of the desired signal and desensitization from strong adjacent signals. b} Oscillator instability requiring frequent retuning, and loss of ability to recover the opposite sideband, should it be transmitted. c} Cross-modulation of the desired signal and insufficient audio power to operate the speaker. d} Oscillator instability and severe audio distortion of all but the strongest received signals. |
a} Cross-modulation of the desired signal and desensitization
from strong adjacent signals. |
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121] The ability of a communications receiver to perform well
in the presence of strong signals outside the band of interest is indicated by what parameter? a} Noise figure. b} Blocking dynamic range. c} Signal-to-noise ratio. d} Audio output. |
b} Blocking dynamic range.
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122] What is meant by the term noise figure of a communications receiver?
a} The level of noise entering the receiver from the antenna. b} The relative strength of a received signal 3 kHz removed from the carrier frequency. c} The level of noise generated in the front end and succeeding stages of a receiver. d} The ability of a receiver to reject unwanted signals at frequencies close to the desired one. |
c} The level of noise generated in the front end and succeeding
stages of a receiver. |
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123] Which stage of a receiver primarily establishes its noise
figure? a} The audio stage. b} The IF strip. c} The RF stage. d} The local oscillator. |
c} The RF stage.
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124] What is an inverting op-amp circuit?
a} An operational amplifier circuit connected such that the input and output signals are 180 degrees out of phase. b} An operational amplifier circuit connected such that the input and output signals are in phase. c} An operational amplifier circuit connected such that the input and output signals are 90 degrees out of phase. d} An operational amplifier circuit connected such that the input impedance is held at zero, while the output impedance is high. |
a} An operational amplifier circuit connected such that the
input and output signals are 180 degrees out of phase. |
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125] What is a noninverting op-amp circuit?
a} An operational amplifier circuit connected such that the input and output signals are 180 degrees out of phase. b} An operational amplifier circuit connected such that the input and output signals are in phase. c} An operational amplifier circuit connected such that the input and output signals are 90 degrees out of phase. d} An operational amplifier circuit connected such that the input impedance is held at zero while the output impedance is high. |
b} An operational amplifier circuit connected such that the
input and output signals are in phase. |
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126] How does the gain of a theoretically ideal operational
amplifier vary with frequency? a} The gain increases linearly with increasing frequency. b} The gain decreases linearly with increasing frequency. c} The gain decreases logarithmically with increasing frequency. d} The gain does not vary with frequency. |
d} The gain does not vary with frequency.
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127] What determines the input impedance in a FET
common-source amplifier? a} The input impedance is essentially determined by the resistance between the drain and substrate. b} The input impedance is essentially determined by the resistance between the source and drain. c} The input impedance is essentially determined by the gate biasing network. d} The input impedance is essentially determined by the resistance between the source and substrate. |
c} The input impedance is essentially determined by the gate
biasing network. |
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128] What determines the output impedance in a FET
common-source amplifier? a} The output impedance is essentially determined by the drain resistor. b} The output impedance is essentially determined by the input impedance of the FET. c} The output impedance is essentially determined by the drain supply voltage. d} The output impedance is essentially determined by the gate supply voltage. |
a} The output impedance is essentially determined by the drain
resistor. |
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129] What is the purpose of a bypass capacitor?
a} It increases the resonant frequency of the circuit. b} It removes direct current from the circuit by shunting DC to ground. c} It removes alternating current by providing a low impedance path to ground. d} It acts as a voltage divider. |
c} It removes alternating current by providing a low impedance
path to ground. |
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130] What is the purpose of a coupling capacitor?
a} It blocks direct current and passes alternating current. b} It blocks alternating current and passes direct current. c} It increases the resonant frequency of the circuit. d} It decreases the resonant frequency of the circuit. |
a} It blocks direct current and passes alternating current.
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131] 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. |
c} It must have positive feedback sufficient to overcome
losses. |
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132] (Refer to figure EL3F2) What is the voltage drop across
R1? a} 9 volts. b} 7 volts. c} 5 volts. d} 3 volts |
c} 5 volts.
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133] (Refer to figure EL3F3) What is the voltage drop across
R1? a} 1.2 volts. b} 2.4 volts. c} 3.7 volts. d} 9 volts. |
d} 9 volts.
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134] In a properly operating marine transmitter, if the power
supply bleeder resistor opens: a} Short circuit of supply voltage due to overload. b} Regulation would decrease. c} Next stage would fail due to short circuit. d} Filter capacitors might short from voltage surge. |
d} Filter capacitors might short from voltage surge.
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135] (Refer to figure EL3F4) Which of the following can occur
that would least affect this circuit? a} C1 shorts. b} C1 opens. c} C3 shorts. d} C18 opens |
d} C18 opens
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136] (Refer to figure EL3F5) When S1 is closed, lights L1 and
L2 go on. What is the condition of both lamps when both S1 and S2 are closed? a} both lamps stay on. b} L1 turns off; L2 stays on. c} both lamps turn off. d} L1 stays on; L2 turns off. |
d} L1 stays on; L2 turns off.
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137] (Refer to figure EL3F5) If S1 is closed both lamps light,
what happens when S1 and S2 are closed? a} L1 and L2 are off. b} L1 is on and L2 is flashing. c} L1 is off and L2 is on. d} L1 is on and L2 is off |
d} L1 is on and L2 is off
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138] (Refer to figure EL3F6) How can we correct the defect, if
any, in this voltage doubler circuit? a} Omit C1. b} Reverse polarity signs. c} Ground X. d} Reverse polarity on C1. |
b} Reverse polarity signs.
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139] (Refer to figure EL3F7) What change is needed in order
to correct the grounded emitter amplifier shown? a} No change is necessary. b} Polarities of emitter-base battery should be reversed. c} Polarities of collector-base battery should be reversed. d} Point A should be replaced with a low value capacitor. |
a} No change is necessary.
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