In Figure E7-1, what is the purpose of R3?
A. Fixed bias
B. Emitter bypass
C. Output load resistor
D. Self bias
E7A02
How many output level changes are obtained for every two trigger pulses applied to the input of a "T" flip-flop circuit?
A. None
B. One
C. Two
D. Four
E7A03
Which of the following can divide the frequency of pulse train by 2?
A. An XOR gate
B. A flip-flop
C. An OR gate
D. A multiplexer
E7A04
How many flip-flops are required to divide a signal frequency by 4?
A. 1
B. 2
C. 4
D. 8
E7A05
Which of the following is a circuit that continuously alternates between two unstable states without an external clock?
A. Monostable multivibrator
B. J-K Flip-Flop
C. T Flip-Flop
D. Astable Multivibrator
E7A06
What is a characteristic of a monostable multivibrator?
A. It switches momentarily to the opposite binary state and then returns, after a set time, to its original state
B. It is a clock that produces a continuous square wave oscillating between 1 and 0
C. It stores one bit of data in either a 0 or 1 state
D. It maintains a constant output voltage, regardless of variations in the input voltage
E7A07
What logical operation does an AND gate perform?
A. It produces a logic "0" at its output only if all inputs are logic "1"
B. It produces a logic "1" at its output only if all inputs are logic "1"
C. It produces a logic "1" at its output if only one input is a logic "1"
D. It produces a logic "1" at its output if all inputs are logic "0"
E7A08
What logical operation does a NAND gate perform?
A. It produces a logic "0" at its output only when all inputs are logic "0"
B. It produces a logic "1" at its output only when all inputs are logic "1"
C. It produces a logic "0" at its output if some but not all of its inputs are logic "1"
D. It produces a logic "0" at its output only when all inputs are logic "1"
E7A09
What logical operation does an OR gate perform?
A. It produces a logic "1" at its output if any or all inputs are logic "1"
B. It produces a logic "0" at its output if all inputs are logic "1"
C. It only produces a logic "0" at its output when all inputs are logic "1"
D. It produces a logic "1" at its output if all inputs are logic "0"
E7A10
What logical operation does a NOR gate perform?
A. It produces a logic "0" at its output only if all inputs are logic "0"
B. It produces a logic "1" at its output only if all inputs are logic "1"
C. It produces a logic "0" at its output if any or all inputs are logic "1"
D. It produces a logic "1" at its output only when none of its inputs are logic "0"
E7A11
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 inputs and corresponding outputs for a digital device
D. A table of logic symbols that indicates the low logic states of an op-amp
E7A12
What is the name for logic which represents a logic "1" as a high voltage?
A. Reverse Logic
B. Assertive Logic
C. Negative logic
D. Positive Logic
E7A13
What is the name for logic which represents a logic "0" as a high voltage?
A. Reverse Logic
B. Assertive Logic
C. Negative logic
D. Positive Logic
E7B Amplifiers: Class of operation; vacuum tube and solid-state circuits; distortion and intermodulation; spurious and parasitic suppression; microwave amplifiers
E7B01
For what portion of a signal cycle does a Class AB amplifier operate?
A. More than 180 degrees but less than 360 degrees
B. Exactly 180 degrees
C. The entire cycle
D. Less than 180 degrees
Which class of amplifier, of the types shown, provides the highest efficiency?
A. Class A
B. Class B
C. Class C
D. Class AB
E7B03
Where on the load line of a Class A common emitter amplifier would bias normally be set?
A. Approximately half-way between saturation and cutoff
B. Where the load line intersects the voltage axis
C. At a point where the bias resistor equals the load resistor
D. At a point where the load line intersects the zero bias current curve
E7B04
What can be done to prevent unwanted oscillations in a power amplifier?
A. Tune the stage for maximum SWR
B. Tune both the input and output for maximum power
C. Install parasitic suppressors and/or neutralize the stage
D. Use a phase inverter in the output filter
E7B05
Which of the following amplifier types reduces or eliminates even-order harmonics?
A. Push-push
B. Push-pull
C. Class C
D. Class AB
E7B06
Which of the following is a likely result when a Class C rather than a class AB amplifier is used to amplify a single-sideband phone signal?
A. Intermodulation products will be greatly reduced
B. Overall intelligibility will increase
C. Part of the transmitted signal will be inverted
D. The signal may become distorted and occupy excessive bandwidth
E7B07
How can a vacuum-tube power amplifier be neutralized?
A. By increasing the grid drive
B. By reducing the grid drive
C. By feeding back an out-of-phase component of the output to the input
D. By feeding back an in-phase component of the output to the input
E7B08
Which of the following describes how the loading and tuning capacitors are to be adjusted when tuning a vacuum tube RF power amplifier that employs a pi-network output circuit?
A. The loading capacitor is set to maximum capacitance and the tuning capacitor is adjusted for minimum allowable plate current
B. The tuning capacitor is set to maximum capacitance and the loading capacitor is adjusted for minimum plate permissible current
C. The loading capacitor is adjusted to minimum plate current while alternately adjusting the tuning capacitor for maximum allowable plate current
D. The tuning capacitor is adjusted for minimum plate current, while the loading capacitor is adjusted for maximum permissible plate current
E7B09
In Figure E7-1, what is the purpose of R1 and R2?
A. Load resistors
B. Fixed bias
C. Self bias
D. Feedback
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E7B10 In Figure E7-1, what is the purpose of R3? A. Fixed bias B. Emitter bypass C. Output load resistor D. Self bias
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E7B12
In Figure E7-2, what is the purpose of R?
A. Emitter load
B. Fixed bias
C. Collector load
D. Voltage regulation
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E7B13 In Figure E7-2, what is the purpose of C2? A. Output coupling B. Emitter bypass C. Input coupling D. Hum filtering
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E7B15
What is the effect of intermodulation products in a linear power amplifier?
A. Transmission of spurious signals
B. Creation of parasitic oscillations
C. Low efficiency
D. All of the above
E7B16
Why are third-order intermodulation distortion products of particular concern in linear power amplifiers?
A. Because they are relatively close in frequency to the desired signal
B. Because they are relatively far in frequency from the desired signal
C. Because they invert the sidebands causing distortion
D. Because they maintain the sidebands, thus causing multiple duplicate signals
E7B17
Which of the following is a characteristic of a grounded-grid amplifier?
A. High power gain
B. High filament voltage
C. Low input impedance
D. Low bandwidth
E7B18
What is a klystron?
A. A high speed multivibrator
B. An electron-coupled oscillator utilizing a pentode vacuum tube
C. An oscillator utilizing ceramic elements to achieve stability
D. A VHF, UHF, or microwave vacuum tube that uses velocity modulation
E7B19
What is a parametric amplifier?
A. A type of bipolar operational amplifier with excellent linearity derived from use of very high voltage on the collector
B. A low-noise VHF or UHF amplifier relying on varying reactance for amplification
C. A high power amplifier for HF application utilizing the Miller effect to increase gain
D. An audio push-pull amplifier using silicon carbide transistors for extremely low noise
E7B20
Which of the following devices is generally best suited for UHF or microwave power amplifier applications?
A. FET
B. Nuvistor
C. Silicon Controlled Rectifier
D. Triac
E7C Filters and matching networks: filters and impedance matching networks: types of networks; types of filters; filter applications; filter characteristics; impedance matching; DSP filtering
E7C01
How are the capacitors and inductors of a low-pass filter Pi-network arranged between the network's input and output?
A. Two inductors are in series between the input and output and a capacitor is connected between the two inductors and ground
B. Two capacitors are in series between the input and output and an inductor is connected between the two capacitors and ground
C. An inductor is in parallel with the input, another inductor is in parallel with the output, and a capacitor is in series between the two
D. A capacitor is in parallel with the input, another capacitor is in parallel with the output, and an inductor is in series between the two
E7C02
A T-network with series capacitors and a parallel (shunt)
inductor has which of the following properties?
A. It transforms impedance and is a low-pass filter
B. It transforms reactance and is a low-pass filter
C. It transforms impedance and is a high-pass filter
D. It transforms reactance and is a narrow bandwidth notch filter
E7C03
What advantage does a Pi-L-network have over a Pi-network for impedance matching between the final amplifier of a vacuum-tube type transmitter and an antenna?
A. Greater harmonic suppression
B. Higher efficiency
C. Lower losses
D. Greater transformation range
E7C04
How does a network transform a complex impedance to a resistive impedance?
A. It introduces negative resistance to cancel the resistive part of an impedance
B. It introduces transconductance to cancel the reactive part of an impedance
C. It cancels the reactive part of an impedance and transforms the resistive part to the desired value
D. Network resistances are substituted for load resistances
E7C05
Which filter type is described as having ripple in the passband and a sharp cutoff?
A. A Butterworth filter
B. An active LC filter
C. A passive op-amp filter
D. A Chebyshev filter
E7C06
What are the distinguishing features of an elliptical filter?
A. Gradual passband rolloff with minimal stop-band ripple
B. Extremely flat response over its passband, with gradually rounded stop-band corners
C. Extremely sharp cutoff, with one or more infinitely deep notches in the stop band
D. Gradual passband rolloff with extreme stop-band ripple
E7C07
What kind of audio filter would you use to attenuate an interfering carrier signal while receiving an SSB transmission?
A. A band-pass filter
B. A notch filter
C. A Pi-network filter
D. An all-pass filter
E7C08
What kind of digital signal processing audio filter might be used to remove unwanted noise from a received SSB signal?
A. An adaptive filter
B. A crystal-lattice filter
C. A Hilbert-transform filter
D. A phase-inverting filter
E7C09
What type of digital signal processing filter might be used in generating an SSB signal?
A. An adaptive filter
B. A notch filter
C. A Hilbert-transform filter
D. An elliptical filter
E7C10
Which of the following filters would be the best choice for use in a 2-meter repeater duplexer?
A. A crystal filter
B. A cavity filter
C. A DSP filter
D. An L-C filter
E7C11
Which of the following is the common name for a filter network which is equivalent to two L networks back-to-back?
A. Pi-L
B. Cascode
C. Omega
D. Pi
E7C12
What is a Pi-L network, as used when matching a vacuum-tube final amplifier to a 50-ohm unbalanced output?
A. A Phase Inverter Load network
B. A network consisting of two series inductors and two shunt capacitors
C. A network with only three discrete parts
D. A matching network in which all components are isolated from ground
E7C13
What is one advantage of a Pi matching network over an L matching network?
A. Q of Pi networks can be varied depending on the component values chosen
B. L networks can not perform impedance transformation
C. Pi networks have fewer components
D. Pi networks are designed for balanced input and output
E7C14
Which of these modes is most affected by non-linear phase response in a receiver IF filter?
A. Meteor Scatter
B. Single-Sideband Voice
C. Digital
D. Video
E7D Power supplies and voltage regulators
E7D01
What is one characteristic of a linear electronic voltage regulator?
A. It has a ramp voltage as its output
B. It eliminates the need for a pass transistor
C. The control element duty cycle is proportional to the line or load conditions
D. The conduction of a control element is varied to maintain a constant output voltage
E7D02
What is one characteristic of a switching electronic voltage regulator?
A. The resistance of a control element is varied in direct proportion to the line voltage or load current
B. It is generally less efficient than a linear regulator
C. The control device’s duty cycle is controlled to produce a constant average output voltage
D. It gives a ramp voltage at its output
E7D03
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
E7D04
Which of the following types of linear regulator makes the most efficient use of the primary power source?
A. A constant current source
B. A series regulator
C. A shunt regulator
D. A shunt current source
E7D05
Which of the following types of linear voltage regulator places 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
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E7D06 What is the purpose of Q1 in the circuit shown in Figure E7-3? A. It provides negative feedback to improve regulation B. It provides a constant load for the voltage source C. It increases the current-handling capability of the regulator D. It provides D1 with current
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E7D07 What is the purpose of C2 in the circuit shown in Figure E7-3? A. It bypasses hum around D1 B. It is a brute force filter for the output C. To self-resonate at the hum frequency D. To provide fixed DC bias for Q1
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E7D08 What type of circuit is shown in Figure E7-3? A. Switching voltage regulator B. Grounded emitter amplifier C. Linear voltage regulator D. Emitter follower
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E7D09 What is the purpose of C1 in the circuit shown in Figure E7-3? A. It resonates at the ripple frequency B. It provides fixed bias for Q1 C. It decouples the output D. It filters the supply voltage
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E7D10 What is the purpose of C3 in the circuit shown in Figure E7-3? A. It prevents self-oscillation B. It provides brute force filtering of the output C. It provides fixed bias for Q1 D. It clips the peaks of the ripple
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E7D11 What is the purpose of R1 in the circuit shown in Figure E7-3? A. It provides a constant load to the voltage source B. It couples hum to D1 C. It supplies current to D1 D. It bypasses hum around D1
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E7D12 What is the purpose of R2 in the circuit shown in Figure E7-3? A. It provides fixed bias for Q1 B. It provides fixed bias for D1 C. It decouples hum from D1 D. It provides a constant minimum load for Q1
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E7D13 What is the purpose of D1 in the circuit shown in Figure E7-3? A. To provide line voltage stabilization B. To provide a voltage reference C. Peak clipping D. Hum filtering
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E7D15
What is the purpose of a "step-start" circuit in a high-voltage power supply?
A. To provide a dual-voltage output for reduced power applications
B. To compensate for variations of the incoming line voltage
C. To allow for remote control of the power supply
D. To allow the filter capacitors to charge gradually
E7D16
When several electrolytic filter capacitors are connected in series to increase the operating voltage of a power supply filter circuit, why should resistors be connected across each capacitor?
A. To equalize, as much as possible, the voltage drop across each capacitor
B. To provide a safety bleeder to discharge the capacitors when the supply is off
C. To provide a minimum load current to reduce voltage excursions at light loads
D. All of these answers are correct
E7D17
What is the primary reason that a high-frequency inverter type high-voltage power supply can be both less expensive and lighter in weight than a conventional power supply?
A. The inverter design does not require any output filtering
B. It uses a diode bridge rectifier for increased output
C. The high frequency inverter design uses much smaller transformers and filter components for an equivalent power output
D. It uses a large power-factor compensation capacitor to create "free" power from the unused portion of the AC cycle
E7E Modulation and demodulation: reactance, phase and balanced modulators; detectors; mixer stages; DSP modulation and demodulation; software defined radio systems
E7E01 (B)
Which of the following can be used to generate FM-phone emissions?
A. A balanced modulator on the audio amplifier
B. A reactance modulator on the oscillator
C. A reactance modulator on the final amplifier
D. A balanced modulator on the oscillator
E7E02
What is the function of a reactance modulator?
A. To produce PM signals by using an electrically variable resistance
B. To produce AM signals by using an electrically variable inductance or capacitance
C. To produce AM signals by using an electrically variable resistance
D. To produce PM signals by using an electrically variable inductance or capacitance
E7E03
What is the fundamental principle of a phase modulator?
A. It varies the tuning of a microphone preamplifier to produce PM signals
B. It varies the tuning of an amplifier tank circuit to produce AM signals
C. It varies the tuning of an amplifier tank circuit to produce PM signals
D. It varies the tuning of a microphone preamplifier to produce AM signals
E7E04
What is one way a single-sideband phone signal can be generated?
A. By using a balanced modulator followed by a filter
B. By using a reactance modulator followed by a mixer
C. By using a loop modulator followed by a mixer
D. By driving a product detector with a DSB signal
E7E05
What circuit is added to an FM transmitter to proportionally attenuate the lower audio frequencies?
A. A de-emphasis network
B. A heterodyne suppressor
C. An audio prescaler
D. A pre-emphasis network
E7E06
What circuit is added to an FM receiver to restore attenuated lower audio frequencies?
A. A de-emphasis network
B. A heterodyne suppressor
C. An audio prescaler
D. A pre-emphasis network
E7E07
What is one result of the process of mixing two signals?
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. The recovery of the intelligence from a modulated RF signal
D. The creation of new signals at the sum and difference frequencies
E7E08
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
E7E09
What occurs when an excessive amount of signal energy reaches a mixer circuit?
A. Spurious mixer products are generated
B. Mixer blanking occurs
C. Automatic limiting occurs
D. A beat frequency is generated
E7E10
What is the process of detection?
A. The extraction of weak signals from noise
B. The recovery of information from a modulated RF signal
C. The modulation of a carrier
D. The mixing of noise with a received signal
E7E11
How does a diode detector function?
A. By rectification and filtering of RF signals
B. By breakdown of the Zener voltage
C. By mixing signals with noise in the transition region of the diode
D. By sensing the change of reactance in the diode with respect to frequency
E7E12
Which of the following types of detector is well suited for demodulating SSB signals?
A. Discriminator
B. Phase detector
C. Product detector
D. Phase comparator
E7E13
What is a frequency discriminator?
A. An FM generator circuit
B. A circuit for filtering two closely adjacent signals
C. An automatic band-switching circuit
D. A circuit for detecting FM signals
E7E14
Which of the following describes a common means of generating a SSB signal when using digital signal processing?
A. Mixing products are converted to voltages and subtracted by adder circuits
B. A frequency synthesizer removes the unwanted sidebands
C. Emulation of quartz crystal filter characteristics
D. The phasing or quadrature method
E7E15
What is meant by direct conversion when referring to a software defined receiver?
A. Software is converted from source code to object code during operation of the receiver
B. Incoming RF is converted to the IF frequency by rectification to generate the control voltage for a voltage controlled oscillator
C. Incoming RF is mixed to baseband for analog-to-digital conversion and subsequent processing
D. Software is generated in machine language, avoiding the need for compilers
E7F Frequency markers and counters: frequency divider circuits; frequency marker generators; frequency counters
E7F01
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 a higher frequency signal so a low-frequency counter can display the operating frequency
C. It prevents oscillation in a low-frequency counter circuit
D. It divides a higher frequency signal so a low-frequency counter can display the operating frequency
E7F02
Which of the following would be used to reduce a signal’s frequency by a factor of ten?
A. A preamp
B. A prescaler
C. A marker generator
D. A flip-flop
E7F03
What is the function of a decade counter digital IC?
A. It produces one output pulse for every ten input pulses
B. It decodes a decimal number for display on a seven-segment LED display
C. It produces ten output pulses for every input pulse
D. It adds two decimal numbers together
E7F04
What additional circuitry must be added to a 100-kHz crystal-controlled marker generator so as to provide markers at 50 and 25 kHz?
A. An emitter-follower
B. Two frequency multipliers
C. Two flip-flops
D. A voltage divider
E7F05
Which of the following circuits can be combined to produce a 100 kHz fundamental signal with harmonics at 100 kHz intervals?
A. A 10 MHz oscillator and a flip-flop
B. A 1 MHz oscillator and a decade counter
C. A 1 MHz oscillator and a flip-flop
D. A 100 kHz oscillator and a phase detector
E7F06
Which of these choices best describes a crystal 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 crystal-controlled oscillator with an output frequency and amplitude that can be varied over a wide range
D. A crystal-controlled oscillator that generates a series of reference signals at known frequency intervals
E7F07
Which type of circuit would be a good choice for generating a series of harmonically related receiver calibration signals?
A. A Wein-bridge oscillator followed by a class-A amplifier
B. A Foster-Seeley discriminator
C. A phase-shift oscillator
D. A crystal oscillator followed by a frequency divider
E7F08
What is one purpose of a marker generator?
A. To add audio markers to an oscilloscope
B. To provide a frequency reference for a phase locked loop
C. To provide a means of calibrating a receiver's frequency settings
D. To add time signals to a transmitted signal
E7F09
What determines the accuracy of a frequency counter?
A. The accuracy of the time base
B. The speed of the logic devices used
C. Accuracy of the AC input frequency to the power supply
D. Proper balancing of the mixer diodes
E7F10
How does a conventional frequency counter determine the frequency of a signal?
A. It counts the total number of pulses in a circuit
B. It monitors a WWV reference signal for comparison with the measured signal
C. It counts the number of input pulses occurring within a specific period of time
D. It converts the phase of the measured signal to a voltage which is proportional to the frequency
E7F11
What is the purpose of a frequency counter?
A. To provide a digital representation of the frequency of a signal
B. To generate a series of reference signals at known frequency intervals
C. To display all frequency components of a transmitted signal
D. To provide a signal source at a very accurate frequency
E7F12
What alternate method of determining frequency, other than by directly counting input pulses, is used by some frequency counters?
A. GPS averaging
B. Period measurement
C. Prescaling
D. D/A conversion
E7F13
What is an advantage of a period-measuring frequency counter over a direct-count type?
A. It can run on battery power for remote measurements
B. It does not require an expensive high-precision time base
C. It provides improved resolution of signals within a comparable time period
D. It can directly measure the modulation index of an FM transmitter
E7G Active filters and op-amps: active audio filters; characteristics; basic circuit design; operational amplifiers
E7G01
What determines the gain and frequency characteristics of an op-amp RC active filter?
A. The values of capacitors and resistors built into the op-amp
B. The values of capacitors and resistors external to the op-amp
C. The input voltage and frequency of the op-amp's DC power supply
D. The output voltage and smoothness of the op-amp's DC power supply
E7G02
What causes ringing in a filter?
A. The slew rate of the filter
B. The bandwidth of the filter
C. The frequency and phase response of the filter
D. The gain of the filter
E7G03
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 varieties than are LC elements
D. Op-amps exhibit gain rather than insertion loss
E7G04
Which of the following capacitor types is best suited for use in high-stability op-amp RC active filter circuits?
A. Electrolytic
B. Disc ceramic
C. Polystyrene
D. Paper dielectric
E7G05
How can unwanted ringing and audio instability be prevented in a multi-section 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
E7G06
What steps are typically followed when selecting the external components for an op-amp RC active filter?
A. Standard capacitor values are chosen first, the resistances are calculated, and resistors of the nearest standard value are used
B. Standard resistor values are chosen first, the capacitances are calculated, and capacitors of the nearest standard value are used
C. Standard resistor and capacitor values are used, the circuit is tested, and additional resistors are added to make any needed adjustments
D. Standard resistor and capacitor values are used, the circuit is tested, and additional capacitors are added to make any needed adjustments
E7G07
Which of the following is the most appropriate use of an op-amp RC active filter?
A. As a high-pass filter used to block RFI at the input to receivers
B. As a low-pass filter used between a transmitter and a transmission line
C. For smoothing power-supply output
D. As an audio receiving filter
E7G08
Which of the following is a type of active op-amp filter circuit?
A. Regenerative feedback resonator
B. Helical resonator
C. Gilbert cell
D. Sallen-Key
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E7G09 What voltage gain can be expected from the circuit in Figure E7-4 when R1 is 10 ohms and RF is 470 ohms? A. 0.21 D. 24
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E7G10 How does the gain of a theoretically ideal operational amplifier vary with frequency? A. It increases linearly with increasing frequency B. It decreases linearly with increasing frequency C. It decreases logarithmically with increasing frequency D. It does not vary with frequency
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E7G11 What will be the output voltage of the circuit shown in Figure E7-4 if R1 is 1000 ohms, RF is 10,000 ohms, and 0.23 volts is applied to the input? A. 0.23 volts B. 2.3 volts C. -0.23 volts D. -2.3 volts
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E7G12 What voltage gain can be expected from the circuit in Figure E7-4 when R1 is 1800 ohms and RF is 68 kilohms? A. 1 B. 0.03 C. 38 D. 76
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E7G13 What voltage gain can be expected from the circuit in Figure E7-4 when R1 is 3300 ohms and RF is 47 kilohms? A. 28 B. 14 C. 7 D. 0.07
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E7G15
What is meant by the term "op-amp input-offset voltage"?
A. The output voltage of the op-amp minus its input voltage
B. The difference between the output voltage of the op-amp and the input voltage required in the immediately following stage
C. The potential between the amplifier input terminals of the op-amp in a closed-loop condition
D. The potential between the amplifier input terminals of the op-amp in an open-loop condition
E7G16
What is the typical input impedance of an integrated circuit op-amp?
A. 100 ohms
B. 1000 ohms
C. Very low
D. Very high
E7G17
What is the typical output impedance of an integrated circuit op-amp?
A. Very low
B. Very high
C. 100 ohms
D. 1000 ohms
E7H Oscillators and signal sources: types of oscillators;
synthesizers and phase-locked loops; direct digital synthesizer
E7H01
What are three major oscillator circuits often used in Amateur Radio equipment?
A. Taft, Pierce and negative feedback
B. Pierce, Fenner and Beane
C. Taft, Hartley and Pierce
D. Colpitts, Hartley and Pierce
E7H02
What condition must exist for a circuit to oscillate?
A. It must have at least two stages
B. It must be neutralized
C. It must have a positive feedback loop with a gain greater than 1
D. It must have negative feedback sufficient to cancel the input signal
E7H03
How is positive feedback supplied in a Hartley oscillator?
A. Through a tapped coil
B. Through a capacitive divider
C. Through link coupling
D. Through a neutralizing capacitor
E7H04
How is positive feedback supplied in a Colpitts oscillator?
A. Through a tapped coil
B. Through link coupling
C. Through a capacitive divider
D. Through a neutralizing capacitor
E7H05
How is positive feedback supplied in a Pierce oscillator?
A. Through a tapped coil
B. Through link coupling
C. Through a neutralizing capacitor
D. Through a quartz crystal
E7H06
Which type of oscillator circuits are commonly used in VFOs?
A. Pierce and Zener
B. Colpitts and Hartley
C. Armstrong and deForest
D. Negative feedback and Balanced feedback
E7H07(C)
What is a magnetron oscillator?
A. An oscillator in which the output is fed back to the input by the magnetic field of a transformer
B. An crystal oscillator in which variable frequency is obtained by placing the crystal in a strong magnetic field
C. A UHF or microwave oscillator consisting of a diode vacuum tube with a specially shaped anode, surrounded by an external magnet
D. A reference standard oscillator in which the oscillations are synchronized by magnetic coupling to a rubidium gas tube
E7H08
What is a Gunn diode oscillator?
A. An oscillator based on the negative resistance properties of properly-doped semiconductors
B. An oscillator based on the argon gas diode
C. A highly stable reference oscillator based on the tee-notch principle
D. A highly stable reference oscillator based on the hot-carrier effect
E7H09
What type of frequency synthesizer circuit uses a stable voltage-controlled oscillator, programmable divider, phase detector, loop filter and a reference frequency source?
A. A direct digital synthesizer
B. A hybrid synthesizer
C. A phase locked loop synthesizer
D. A diode-switching matrix synthesizer
E7H10
What type of frequency synthesizer circuit uses a phase accumulator, lookup table, digital to analog converter and a low-pass anti-alias filter?
A. A direct digital synthesizer
B. A hybrid synthesizer
C. A phase locked loop synthesizer
D. A diode-switching matrix synthesizer
E7H11
What information is contained in the lookup table of a direct digital frequency synthesizer?
A. The phase relationship between a reference oscillator and the output waveform
B. The amplitude values that represent a sine-wave output
C. The phase relationship between a voltage-controlled oscillator and the output waveform
D. The synthesizer frequency limits and frequency values stored in the radio memories
E7H12
What are the major spectral impurity components of direct digital synthesizers?
A. Broadband noise
B. Digital conversion noise
C. Spurs at discrete frequencies
D. Nyquist limit noise
E7H13
Which of these circuits would be classified as a principal component of a direct digital synthesizer (DDS)
?
A. Phase splitter
B. Hex inverter
C. Chroma demodulator
D. Phase accumulator
E7H14
What circuit is often used in conjunction with a direct digital synthesizer (DDS)
to expand the available tuning range?
A. Binary expander
B. J-K flip-flop
C. Phase locked loop
D. Compander
E7H15
What is the capture range of a phase-locked loop circuit?
A. The frequency range over which the circuit can lock
B. The voltage range over which the circuit can lock
C. The input impedance range over which the circuit can lock
D. The range of time it takes the circuit to lock
E7H16
What is a phase-locked loop circuit?
A. An electronic servo loop consisting of a ratio detector, reactance modulator, and voltage-controlled oscillator
B. An electronic circuit also known as a monostable multivibrator
C. An electronic servo loop consisting of a phase detector, a low-pass filter and voltage-controlled oscillator
D. An electronic circuit consisting of a precision push-pull amplifier with a differential input
E7H17
Which of these functions can be performed by a phase-locked loop?
A. Wide-band AF and RF power amplification
B. Comparison of two digital input signals, digital pulse counter
C. Photovoltaic conversion, optical coupling
D. Frequency synthesis, FM demodulation
E7H18
Why is a stable reference oscillator normally 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
E7H19
Why is a phase-locked loop often used as part of a variable frequency synthesizer for receivers and transmitters?
A. It generates FM sidebands
B. It eliminates the need for a voltage controlled oscillator
C. It makes it possible for a VFO to have the same degree of stability as a crystal oscillator
D. It can be used to generate or demodulate SSB signals by quadrature phase synchronization
E7H20
What are the major spectral impurity components of phase-locked loop synthesizers?
A. Broadband noise
B. Digital conversion noise
C. Spurs at discrete frequencies
D. Nyquist limit noise