Element #3F....Good
luck!...and remember you will be asked 17 questions from this pool.
(E3F1) What is a linear electronic voltage regulator?
A regulator that has a ramp voltage as its output.
A regulator in which the pass transistor switches from the "off1 state to the "on" state.
A regulator in which the control device is switched on or off, with the duty cycle proportional to the line or load conditions.
A regulator in which the conduction of a control element is varied in direct proportion to the line voltage or load current.
(E3F2) What is a switching electronic voltage regulator?
A regulator in which the conduction of a control element is varied in direct proportion to the line voltage or load current.
A regulator that provides more than one output voltage.
A regulator in which the control device is switched on or off, with the duty cycle proportional to the line or load conditions.
A regulator that gives a ramp voltage at its output.
(E3F3) What device is usually used as a stable reference voltage in a linear voltage regulator?
A Zener diode.
A tunnel diode.
An SCR.
A varactor diode.
(E3F4) What type of linear regulator is used in applications requiring efficient utilization of the primary power source?
A constant current source.
A series regulator.
A shunt regulator.
A shunt current source.
(E3F5) What type of linear voltage regulator is used in applications where the load on the unregulated voltage source must be kept constant?
A constant current source.
A series regulator.
A shunt current source.
A shunt regulator.
(E3F6) To obtain the best temperature stability, what should be the operating voltage of the reference diode in a linear voltage regulator?
Approximately 2.0 volts.
Approximately 3.0 volts.
Approximately 6.0 volts.
Approximately 10.0 volts.
(E3F7) What is the meaning of the term remote sensing with regard to a linear voltage regulator?
The feedback connection to the error amplifier is made directly to the load.
Sensing is accomplished by wireless inductive loops.
The load connection is made outside the feedback loop.
The error amplifier compares the input voltage to the reference voltage.
(E3F8) What is a three-terminal regulator?
A regulator that supplies three voltages with variable current.
A regulator that supplies three voltages at a constant current.
A regulator containing three error amplifiers and sensing transistors.
A regulator containing a voltage reference, error amplifier, sensing resistors and transistors, and a pass element.
(E3F9) What are the important characteristics of a three-terminal regulator?
Maximum and minimum input voltage, minimum output current and voltage.
Maximum and minimum input voltage, maximum output current and voltage.
Maximum and minimum input voltage, minimum output current and maximum output voltage.
Maximum and minimum input voltage, minimum output voltage and maximum output current.
(E3F10) What is the distinguishing feature of a Class A amplifier?
Output for less than 180 degrees of the signal cycle.
Output for the entire 360 degrees of the signal cycle.
Output for more than 180 degrees and less than 360 degrees of the signal cycle.
Output for exactly 180 degrees of the input signal cycle.
(E3F11) 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?
Class A.
Class B.
Class C.
Class D.
(E3F12) What is the distinguishing characteristic of a Class B amplifier?
Output for the entire input signal cycle.
Output for greater than 180 degrees and less than 360 degrees of the input signal cycle.
Output for less than 180 degrees of the input signal cycle.
Output for 180 degrees of the input signal cycle.
(E3F13) What class of amplifier is distinguished by the flow of current in the output essentially in 180 degree pulses?
Class A.
Class B.
Class C.
Class D.
(E3F14) What is a Class AB amplifier?
Output is present for more than 180 degrees but less than 360 degrees of the signal input cycle.
Output is present for exactly 180 degrees of the input signal cycle.
Output is present for the entire input signal cycle.
Output is present for less than 180 degrees of the input signal cycle.
(E3F15) What is the distinguishing feature of a Class C amplifier?
Output is present for less than 180 degrees of the input signal cycle.
Output is present for exactly 180 degrees of the input signal cycle.
Output is present for the entire input signal cycle.
Output is present for more than 180 degrees but less than 360 degrees of the input signal cycle.
(E3F16) What class of amplifier is distinguished by the bias being set well beyond cutoff?
Class A.
Class B.
Class C.
Class AB.
(E3F17) Which class of amplifier provides the highest efficiency?
Class A.
Class B.
Class C.
Class AB.
(E3F18) Which class of amplifier has the highest linearity and least distortion?
Class A.
Class B.
Class C.
Class AB.
(E3F19) 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?
Class A.
Class B.
Class C.
Class AB.
(E3F20) What is an L-network?
A network consisting entirely of four inductors.
A network consisting of an inductor and a capacitor.
A network used to generate a leading phase angle.
A network used to generate a lagging phase angle.
(E3F21) What is a pi-network?
A network consisting entirely of four inductors or four capacitors.
A Power Incidence network.
An antenna matching network that is isolated from ground.
A network consisting of one inductor and two capacitors or two inductors and one capacitor.
(E3F22) What is a pi-L-network?
A Phase Inverter Load network.
A network consisting of two inductors and two capacitors.
A network with only three discrete parts.
A matching network in which all components are isolated from ground.
(E3F23) Which network provides the greatest harmonic suppression?
L-network.
Pi-network.
Inverse L-network.
Pi-L-network.
(E3F24) What are the three most commonly used networks to accomplish a match between an amplifying device and a transmission line?
M-network, pi-network and T-network.
T-network, M-network and Q-network.
L-network, pi-network and pi-L-network.
L-network, M-network and C-network.
(E3F25) How are networks able to transform one impedance to another?
Resistances in the networks substitute for resistances in the load.
The matching network introduces negative resistance to cancel the resistive part of an impedance.
The matching network introduces transconductance to cancel the reactive part of an impedance
The matching network can cancel the reactive part of an impedance and change the value of the resistive part of an impedance.
(E3F26) Which type of network offers the greater transformation ratio?
L-network.
Pi-network.
Constant-K.
Constant-M.
(E3F27) Why is the L-network of limited utility in impedance matching?
It matches a small impedance range.
It has limited power handling capabilities.
It is thermally unstable.
It is prone to self resonance.
(E3F28) 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?
Greater transformation range.
Higher efficiency.
Lower losses.
Greater harmonic suppression.
(E3F29) Which type of network provides the greatest harmonic suppression?
L-network.
Pi-network.
Pi-L-network.
Inverse-Pi network.
(E3F30) What are the three general groupings of niters?
High-pass, low-pass and band-pass.
Inductive, capacitive and resistive.
Audio, radio and capacitive.
Hartley, Colpitts and Pierce.
(E3F31) What is a constant-K filter?
A filter that uses Boltzmann's constant.
A filter whose velocity factor is constant over a wide range of frequencies.
A filter whose product of the series- and shunt-element impedances is a constant for all frequencies.
A filter whose input impedance varies widely over the design bandwidth.
(E3F32) What is an advantage of a constant-k filter?
It has high attenuation for signals on frequencies far removed from the passband.
It can match impedances over a wide range of frequencies.
It uses elliptic functions.
The ratio of the cutoff frequency to the trap frequency can be varied.
(E3F33) What is an m-derived filter?
A filter whose input impedance varies widely over the design bandwidth.
A filter whose product of the series- and shunt-element impedances is a constant for all frequencies.
A filter whose schematic shape is the letter "M".
A filter that uses a trap to attenuate undesired frequencies too near cutoff for a constant-k filter.
(E3F34) What are the distinguishing features of a Butterworth filter?
A filter whose product of the series- and shunt-element impedances is a constant for all frequencies.
It only requires capacitors.
It has a maximally flat response over its passband.
It requires only inductors.
(E3F35) What are the distinguishing features of a Chebyshev filter?
It has a maximally flat response over its passband.
It allows ripple in the passband.
It only requires inductors.
A filter whose product of the series- and shunt-element impedances is a constant for all frequencies.
(E3F36) When would it be more desirable to use an m-derived filter over a constant-k filter?
When the response must be maximally flat at one frequency.
When you need more attenuation at a certain frequency that is too close to the cut-off frequency for a constant-k filter.
When the number of components must be minimized.
When high power levels must be filtered.
(E3F37) What are three major oscillator circuits often used in radio equipment?
Taft, Pierce, and negative feedback.
Colpitts, Hartley, and Taft.
Taft, Hartley, and Pierce.
Colpitts, Hartley, and Pierce.
(E3F38) How is the positive feedback coupled to the input in a Hartley oscillator?
Through a neutralizing capacitor.
Through a capacitive divider.
Through link coupling.
Through a tapped coil.
(E3F39) How is the positive feedback coupled to the input in a Colpitts oscillator?
Through a tapped coil.
Through link coupling.
Through a capacitive divider.
Through a neutralizing capacitor.
(E3F40) How is the positive feedback coupled to the input in a Pierce oscillator?
Through a tapped coil.
Through link coupling.
Through a capacitive divider.
Through capacitive coupling.
(E3F41) Which of the three major oscillator circuits used in radio equipment utilizes a quartz crystal?
Negative feedback.
Hartley.
Colpitts.
Pierce.
(E3F42) What is the piezoelectric effect?
Mechanical vibration of a crystal by the application of a voltage.
Mechanical deformation of a crystal by the application of a magnetic field.
The generation of electrical energy by the application of light.
Reversed conduction states when a P-N junction is exposed to light.
(E3F43) What is the major advantage of a Pierce oscillator?
It is easy to neutralize.
It doesn't require an LC tank circuit.
It can be tuned over a wide range.
It has a high output power.
(E3F44) Which type of oscillator circuit is commonly used in a VFO?
Pierce.
Colpitts.
Hartley.
Negative feedback.
(E3F45) Why is the Colpitts oscillator circuit commonly used in a VFO?
The frequency is a linear function of the load impedance.
It can be used with or without crystal lock-in.
It is stable.
It has high output power.
(E3F46) What is meant by the term: modulation?
The squelching of a signal until a critical signal-to-noise ratio is reached.
Carrier rejection through phase nulling.
A linear amplification mode.
A mixing process whereby information is imposed upon a carrier.
(E3F47) How is a G3E FM-phone emission produced?
With a balanced modulator on the audio amplifier.
With a reactance modulator on the oscillator.
With a reactance modulator on the final amplifier.
With a balanced modulator on the oscillator.
(E3F48) What is a reactance modulator?
A circuit that acts as a variable resistance or capacitance to produce FM signals.
A circuit that acts as a variable resistance or capacitance to produce AM signals.
A circuit that acts as a variable inductance or capacitance to produce FM signals.
A circuit that acts as a variable inductance or capacitance to produce AM signals.
(E3F49) What is a balanced modulator?
An FM modulator that produces a balanced deviation.
A modulator that produces a double sideband, suppressed carrier signal.
A modulator that produces a single sideband, suppressed carrier signal.
A modulator that produces a full carrier signal.
(E3F50) How can a single-sideband phone signal be generated?
By driving a product detector with a DSB signal.
By using a reactance modulator followed by a mixer.
By using a loop modulator followed by a mixer.
By using a balanced modulator followed by a filter.
(E3F51) How can a double-sideband phone signal be generated?
By feeding a phase modulated signal into a low pass filter.
By using a balanced modulator followed by a filter.
By detuning a Hartley oscillator.
By modulating the plate voltage of a class C amplifier.
(E3F52) How is the efficiency of a power amplifier determined?
Efficiency = ( RF power out / DC power in ) X 100%.
Efficiency = ( RF power in / RF power out) X 100%.
Efficiency = ( RF power in / DC power in ) X 100%.
Efficiency = ( DC power in / RF power in ) X 100%.
(E3F53) 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?
100.3 ohms.
14.4 ohms.
10.3 ohms.
144 ohms.
(E3F54) What is the flywheel effect?
The continued motion of a radio wave through space when the transmitter is turned off.
The back and forth oscillation of electrons in an LC circuit.
The use of a capacitor in a power supply to filter rectified AC.
The transmission of a radio signal to a distant station by several hops through the ionosphere.
(E3F55) What order of Q is required by a tank-circuit sufficient to reduce harmonics to an acceptable level?
Approximately 120.
Approximately 12.
Approximately 1200.
Approximately 1.2.
(E3F56) How can parasitic oscillations be eliminated from a power amplifier?
By tuning for maximum SWR.
By tuning for maximum power output.
By neutralization.
By tuning the output.
(E3F57) What is the process of detection?
The process of masking out the intelligence on a received carrier to make an S-meter operational.
The recovery of intelligence from the modulated RF signal.
The modulation of a carrier.
The mixing of noise with the received signal.
(E3F58) What is the principle of detection in a diode detector?
Rectification and filtering of RF.
Breakdown of the Zener voltage.
Mixing with noise in the transition region of the diode.
The change of reactance in the diode with respect to frequency.
(E3F59) What is a product detector?
A detector that provides local oscillations for input to the mixer.
A detector that amplifies and narrows the band-pass frequencies.
A detector that uses a mixing process with a locally generated carrier.
A detector used to detect cross-modulation products.
(E3F60) How are FM-phone signals detected?
By a balanced modulator.
By a frequency discriminator.
By a product detector.
By a phase splitter.
(E3F61) What is a frequency discriminator?
A circuit for detecting FM signals.
A circuit for filtering two closely adjacent signals.
An automatic bandswitching circuit.
An FM generator.
(E3F62) What is the mixing process?
The elimination of noise in a wideband receiver by phase comparison.
The elimination of noise in a wideband receiver by phase differentiation.
Distortion caused by auroral propagation.
The combination of two signals to produce sum and difference frequencies.
(E3F63) What are the principal frequencies that appear at the output of a mixer circuit?
Two and four times the original frequency.
The sum, difference and square root of the input frequencies.
The original frequencies and the sum and difference frequencies.
1.414 and 0.707 times the input frequency.
(E3F64) What are the advantages of the frequency-conversion process?
Automatic squelching and increased selectivity.
Increased selectivity and optimal tuned-circuit design.
Automatic soft limiting and automatic squelching.
Automatic detection in the RF amplifier and increased selectivity.
(E3F65) What occurs in a receiver when an excessive amount of signal energy reaches the mixer circuit?
Spurious mixer products are generated.
Mixer blanking occurs.
Automatic limiting occurs.
A beat frequency is generated.
(E3F66) How much gain should be used in the RF amplifier stage of a receiver?
As much gain as possible short of self oscillation.
Sufficient gain to allow weak signals to overcome noise generated in the first mixer stage.
Sufficient gain to keep weak signals below the noise of the first mixer stage.
It depends on the amplification factor of the first IF stage.
(E3F67) 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?
To prevent the sum and difference frequencies from being generated.
To prevent bleed-through of the desired signal.
To prevent the generation of spurious mixer products.
To prevent bleed-through of the local oscillator.
(E3F68) What is the primary purpose of an RF amplifier in a receiver?
To provide most of the receiver gain.
To vary the receiver image rejection by utilizing the AGC.
To improve the receiver's noise figure.
To develop the AGC voltage.
(E3F69) What is an i-f amplifier stage?
A fixed-tuned pass-band amplifier.
A receiver demodulator.
A receiver filter.
A buffer oscillator.
(E3F70) What factors should be considered when selecting an intermediate frequency?
Cross-modulation distortion and interference.
Interference to other services.
Image rejection and selectivity.
Noise figure and distortion.
(E3F71) What is the primary purpose of the first i-f amplifier stage in a receiver?
Noise figure performance.
Tune out cross-modulation distortion.
Dynamic response.
Selectivity.
(E3F72) What is the primary purpose of the final i-f amplifier stage in a receiver?
Dynamic response.
Gain.
Noise figure performance.
Bypass undesired signals.
(E3F73) What is a flip-flop circuit?
A binary sequential logic element with one stable state.
A binary sequential logic element with eight stable states.
A binary sequential logic element with four stable states.
A binary sequential logic element with two stable states.
(E3F74) How many bits of information can be stored in a single flip-flop circuit?
1.
2.
3.
4.
(E3F75) What is a bistable multivibrator circuit?
An "AND" gate.
An "OR" gate.
A flip-flop.
A clock.
(E3F76) How many output changes are obtained for every two trigger pulses applied to the input of a bistable T flip-flop circuit?
No output level changes.
One output level change.
Two output level changes.
Four output level changes.
(E3F77) The frequency of an AC signal can be divided electronically by what type of digital circuit?
A free-running multivibrator.
An OR gate.
A bistable multivibrator.
An astable multivibrator.
(E3F78) What type of digital IC is also known as a latch?
A decade counter.
An OR gate.
A flip-flop.
An op-amp.
(E3F79) How many flip-flops are required to divide a signal frequency by 4?
1.
2.
4.
8.
(E3F80) What is an astable multivibrator?
A circuit that alternates between two stable states.
A circuit that alternates between a stable state and an unstable state.
A circuit set to block either a 0 pulse or a 1 pulse and pass the other.
A circuit that alternates between two unstable states.
(E3F81) What is a monostable multivibrator?
A circuit that can be switched momentarily to the' opposite binary state and then returns after a set time to its original state.
A "clock" circuit that produces a continuous square wave oscillating between 1 and 0.
A circuit designed to store one bit of data in either the 0 or the 1 configuration.
A circuit that maintains a constant output voltage, regardless of variations in the input voltage.
(E3F82) What is an AND gate?
A circuit that produces a logic "1" at its output only if all inputs are logic "1".
A circuit that produces a logic "0" at its output only if all inputs are logic "1".
A circuit that produces a logic "1" at its output if only one input is a logic "1".
A circuit that produces a logic "1" at its output if all inputs are logic "0".
(E3F83) What is a NAND gate?
A circuit that produces a logic "0" at its output only when all inputs are logic "0".
A circuit that produces a logic "1" at its output only when all inputs are logic "1".
A circuit that produces a logic "0" at its output if some but not all of its inputs are logic "1".
A circuit that produces a logic "0" at its output only when all inputs are logic "1".
(E3F84) What is an OR gate?
A circuit that produces a logic "1" at its output if any input is logic "1".
A circuit that produces a logic "0" at its output if any input is logic "1".
A circuit that produces a logic "0" at its output if all inputs are logic "1".
A circuit that produces a logic "1" at its output if all inputs are logic "0".
(E3F85) What is a NOR gate?
A circuit that produces a logic "0" at its output only if all inputs are logic "0".
A circuit that produces a logic "1" at its output only if all inputs are logic "1".
A circuit that produces a logic "0" at its output if any or all inputs are logic "1".
A circuit that produces a logic "1" at its output if some but not all of its inputs are logic "1".
(E3F86) What is a NOT gate?
A circuit that produces a logic "O" at its output when the input is logic "1" and vice versa.
A circuit that does not allow data transmission when its input is high.
A circuit that allows data transmission only when its input is high.
A circuit that produces a logic "1" at its output when the input is logic "1" and vice versa.
(E3F87) What is a truth table?
A table of logic symbols that indicate the high logic states of an op-amp.
A diagram showing logic states when the digital device's output is true.
A list of input combinations and their corresponding outputs that characterizes a digital device's function.
A table of logic symbols that indicates the low logic states of an op-amp.
(E3F88) In a positive-logic circuit, what level is used to represent a logic 1?
A low level.
A positive-transition level.
A negative-transition level.
A high level.
(E3F89) In a positive-logic circuit, what level is used to represent a logic 0?
A low level.
A positive-transition level.
A negative-transition level.
A high level.
(E3F90) In a negative-logic circuit, what level is used to represent a logic 1?
A low level.
A positive-transition level.
A negative-transition level.
A high level.
(E3F91) In a negative-logic circuit, what level is used to represent a logic 0?
A low level.
A positive-transition level.
A negative-transition level.
A high level.
(E3F92) What is a crystal-controlled marker generator?
A low-stability oscillator that "sweeps" through a band of frequencies.
An oscillator often used in aircraft to determine the craft's location relative to the inner and outer markers at airports.
A high-stability oscillator whose output frequency and amplitude can be varied over a wide range.
A high-stability oscillator that generates a series of reference signals at known frequency intervals.
(E3F93) What additional circuitry is required in a 100-kHz crystal-controlled marker generator to provide markers at 50 and 25 kHz?
An emitter-follower.
Two frequency multipliers.
Two flip-flops.
A voltage divider.
(E3F94) What is the purpose of a prescaler circuit?
It converts the output of a JK flip-flop to that of an RS flip-flop.
It multiplies an HF signal so a low-frequency counter can display the operating frequency.
It prevents oscillation in a low frequency counter circuit.
It divides an HF signal so a low-frequency counter can display the operating frequency.
(E3F95) What does the accuracy of a frequency counter depend on?
The internal crystal reference.
A voltage-regulated power supply with an unvarying output.
Accuracy of the AC input frequency to the power supply.
Proper balancing of the power-supply diodes.
(E3F96) How many states does a decade counter digital 1C have?
6.
10.
15.
20.
(E3F97) What is the function of a decade counter digital IC?
Decode a decimal number for display on a seven-segment LED display.
Produce one output pulse for every ten input pulses.
Produce ten output pulses for every input pulse.
Add two decimal numbers.
(E3F98) What are the advantages of using an op-amp instead of LC elements in an audio filter?
Op-amps are more rugged and can withstand more abuse than can LC elements.
Op-amps are fixed at one frequency.
Op-amps are available in more styles and types than are LC elements.
Op-amps exhibit gain rather than insertion loss.
(E3F99) What determines the gain and frequency characteristics of an op-amp RC active filter?
Values of capacitances and resistances built into the op-amp.
Values of capacitances and, resistances external to the op-amp.
Voltage and frequency of DC input to the op-amp power supply.
Regulated DC voltage output from the op-amp power supply.
(E3F100) What are the principle uses of an op-amp RC active filter?
Op-amp circuits are used as high-pass filters to block RFI at the input to receivers.
Op-amp circuits are used as low-pass filters between transmitters and transmission lines.
Op-amp circuits are used as filters for smoothing power-supply output.
Op-amp circuits are used as audio filters for receivers.
(E3F101) What type of capacitors should be used in an op-amp RC active filter circuit?
Electrolytic.
Disc ceramic.
Polystyrene.
Paper dielectric.
(E3F102) How can unwanted ringing and audio instability be prevented in a multisection op-amp RC audio filter circuit?
Restrict both gain and Q.
Restrict gain, but increase Q.
Restrict Q, but increase gain.
Increase both gain and Q.
(E3F103) Where should an op-amp RC active audio filter be placed in a receiver?
In the IF strip, immediately before the detector.
In the audio circuitry immediately before the speaker or phone jack.
Between the balanced modulator and frequency multiplier.
In the low-level audio stages.
(E3F104) What parameter must be selected when designing an audio filter using an op-amp?
Bandpass characteristics.
Desired current gain.
Temperature coefficient.
Output-offset overshoot.
(E3F105) What two factors determine the sensitivity of a receiver?
Dynamic range and third-order intercept.
Cost and availability.
Intermodulation distortion and dynamic range.
Bandwidth and noise figure.
(E3F106) What is the limiting condition for sensitivity in a communications receiver?
The noise floor of the receiver.
The power-supply output ripple.
The two-tone intermodulation distortion.
The input impedance to the detector.
(E3F107) What is the theoretical minimum noise floor of a receiver with a 400-hertz bandwidth?
-141 dBm.
-148 dBm.
-174 dBm.
-180 dBm.
(E3F108) How can selectivity be achieved in the front-end circuitry of a communications receiver?
By using an audio filter.
By using a preselector.
By using an additional RF amplifier stage.
By using an additional IF amplifier stage.
(E3F109) A receiver selectivity of 2.4 kHz in the IF circuitry is optimum for what type of signals?
CW.
SSB voice.
Double-sideband AM voice.
FSKRTTY.
(E3F110) What occurs during CW reception if too narrow a filter bandwidth is used in the IF stage of a receiver?
Undesired signals will reach the audio stage.
Output-offset overshoot.
Cross-modulation distortion.
Filter ringing.
(E3F111) To find the supply power with only a voltmeter, measure between:
Z to W voltage times 150,000. divided by 2000.
Y to Z voltage squared divided by 2000.
W to Y voltage divided by 150.
W to X voltage divided by 150,000 times W to Z voltage.
(E3F112) A receiver selectivity of 10 kHz in the IF circuitry is optimum for what type of signals?
SSB voice.
Double-sideband AM.
CW.
FSKRTTY.
(E3F113) What degree of selectivity is desirable in the IF circuitry of a single-sideband phone receiver?
1 kHz.
2.4kHz.
4.2kHz.
4.8kHz.
(E3F114) What is an undeskable effect of using too wide a filter bandwidth in the IFSection of a receiver?
Output-offset overshoot.
Undesired signals will reach the audio stage.
Thermal-noise distortion.
Filter ringing.
(E3F115) How should the filter bandwidth of a receiver IF section compare with the bandwidth of a received signal?
Filter bandwidth should be slightly greater than the received-signal bandwidth.
Filter bandwidth should be approximately half the received-signal bandwidth.
Filter bandwidth should be approximately two times the received-signal bandwidth.
Filter bandwidth should be approximately four times the received-signal bandwidth.
(E3F116) What degree of selectivity is desirable in the IF circuitry of an FM-phone receiver?
1kHz.
2.4kHz.
4.2kHz.
15kHz.
(E3F117) How can selectivity be achieved in the IF circuitry of a communications receiver?
Incorporate a means of varying the supply voltage to the local oscillator circuitry.
Replace the standard JFET mixer with a bipolar transistor followed by a capacitor of the proper value.
Remove AGC action from the IF stage and confine it to the audio stage only.
Incorporate a high-Q filter.
(E3F118) What is meant by the dynamic range of a communications receiver?
The number of kHz between the lowest and the highest frequency to which the receiver can be tuned.
The maximum possible undistorted audio output of the receiver, referenced to one milliwatt.
The ratio between the minimum discernible signal and the largest tolerable signal without causing audible distortion products.
The difference between the lowest-frequency signal and the highest-frequency signal detectable without moving the tuning knob.
(E3F119) What is the term for the ratio between the largest tolerable receiver input signal and the minimum discernible signal?
Intermodulation distortion.
Noise floor.
Noise figure.
Dynamic range.
(E3F120) What type of problems are caused by poor dynamic range in a communications receiver?
Cross-modulation of the desired signal and desensitization from strong adjacent signals.
Oscillator instability requiring frequent retiming, and loss of ability to recover the opposite sideband, should it be transmitted.
Cross-modulation of the desired signal and insufficient audio power to operate the speaker.
Oscillator instability and severe audio distortion of all but the strongest received signals.
(E3F121) 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?
Noise figure.
Blocking dynamic range.
Signal-to-noise ratio.
Audio output.
(E3F122) What is meant by the term noise figure of a communications receiver?
The level of noise entering the receiver from the antenna.
The relative strength of a received signal 3 kHz removed from the carrier frequency.
The level of noise generated in the front end and succeeding stages of a receiver.
The ability of a receiver to reject unwanted signals at frequencies close to the desired one.
(E3F123) Which stage of a receiver primarily establishes its noise figure?
The audio stage.
The IF strip.
The RF stage.
The local oscillator.
(E3F124) What is an inverting op-amp circuit?
An operational amplifier circuit connected such that the input and output signals are 180 degrees out of phase.
An operational amplifier circuit connected such that the input and output signals are in phase.
An operational amplifier circuit connected such that the input and output signals are 90 degrees out of phase.
An operational amplifier circuit connected such that the input impedance is held at zero, while the output impedance is high.
(E3F125) What is a noninverting op-amp circuit?
An operational amplifier circuit connected such that the input and output signals are 180 degrees out of phase.
An operational amplifier circuit connected such that the input and output signals are in phase.
An operational amplifier circuit connected such that the input and output signals are 90 degrees out of phase.
An operational amplifier circuit connected such that the input impedance is held at zero while the output impedance is high.
(E3F126) How does the gain of a theoretically ideal operational amplifier vary with frequency?
The gain increases linearly with increasing frequency.
The gain decreases linearly with increasing frequency.
The gain decreases logarithmically with increasing frequency.
The gain does not vary with frequency.
(E3F127) What determines the input impedance in a FET common-source amplifier?
The input impedance is essentially determined by the resistance between the drain and substrate.
The input impedance is essentially determined by the resistance between the source and drain.
The input impedance is essentially determined by the gate biasing network.
The input impedance is essentially determined by the resistance between the source and substrate.
(E3F128) What determines the output impedance in a FET common-source amplifier?
The output impedance is essentially determined by the drain resistor.
The output impedance is essentially determined by the input impedance of the FET.
The output impedance is essentially determined by the drain supply voltage.
The output impedance is essentially determined by the gate supply voltage.
(E3F129) What is the purpose of a bypass capacitor?
It increases the resonant frequency of the circuit.
It removes direct current from the circuit by shunting DC to ground.
It removes alternating current by providing a low impedance path to ground.
It acts as a voltage divider.
(E3F130) What is the purpose of a coupling capacitor?
It blocks direct current and passes alternating current.
It blocks alternating current and passes direct current.
It increases the resonant frequency of the circuit.
It decreases the resonant frequency of the circuit.
(E3F131) What condition must exist for a circuit to oscillate?
It must have a gain of less than 1.
It must be neutralized.
It must have positive feedback sufficient to overcome losses.
It must have negative feedback sufficient to cancel the input.
(E3F132) (Refer to figure EL3F2) What is the voltage drop across R1?
9 volts.
7 volts.
5 volts.
3 volts
(E3F133) (Refer to figure EL3F3) What is the voltage drop across R1?
1.2 volts.
2.4 volts.
3.7 volts.
9 volts.
(E3F134) In a properly operating marine transmitter, if the power supply bleeder resistor opens:
Short circuit of supply voltage due to overload.
Regulation would decrease.
Next stage would fail due to short circuit.
Filter capacitors might short from voltage surge.
(E3F135) (Refer to figure EL3F4) Which of the following can occur that would least affect this circuit?
Cl shorts.
Cl opens.
C3 shorts.
C18 opens.
(E3F136) (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?
both lamps stay on.
L1 turns off; L2 stays on.
both lamps turn off.
L1 stays on; L2 turns off.
(E3F137) (Refer to figure EL3F5) If S1 is closed both lamps light, what happens when S1 and S2 are closed?
L1 and L2 are off.
L1 is on and L2 is flashing.
L1 is off and L2 is on.
L1 is on and L2 is off.
(E3F138) (Refer to figure EL3F6) How can we correct the defect, if any, in this voltage doubler circuit?
Omit C1.
Reverse polarity signs.
Ground X.
Reverse polarity on C1.
(E3F139) (Refer to figure EL3F7) What change is needed in order to correct the grounded emitter amplifier shown?
No change is necessary.
Polarities of emitter-base battery should be reversed.
Polarities of collector-base battery should be reversed.
Point A should be replaced with a low value capacitor.
Turn off the
volume if you don't want to hear the sound bites.
