Extra Class License Exam Questions

Subelement E7

Practical Circuits

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Group E7A Digital circuits: digital circuit principles and logic circuits: classes of logic elements; positive and negative logic; frequency dividers; truth tables
E7A01 Which is a bi-stable circuit?
E7A02 What is the function of a decade counter digital IC?
E7A03 Which of the following can divide the frequency of a pulse train by 2?
E7A04 How many flip-flops are required to divide a signal frequency by 4?
E7A05 Which of the following is a circuit that continuously alternates between two states without an external clock?
E7A06 What is a characteristic of a monostable multivibrator?
E7A07 What logical operation does a NAND gate perform?
E7A08 What logical operation does an OR gate perform?
E7A09 What logical operation is performed by an exclusive NOR gate?
E7A10 What is a truth table?
E7A11 What type of logic defines "1" as a high voltage?
E7A12 What type of logic defines "0" as a high voltage?
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Group E7B Amplifiers: Class of operation; vacuum tube and solid-state circuits; distortion and intermodulation; spurious and parasitic suppression; microwave amplifiers; switching-type amplifiers
E7B01 For what portion of a signal cycle does a Class AB amplifier operate?
E7B02 What is a Class D amplifier?
E7B03 Which of the following components form the output of a class D amplifier circuit?
E7B04 Where on the load line of a Class A common emitter amplifier would bias normally be set?
E7B05 What can be done to prevent unwanted oscillations in an RF power amplifier?
E7B06 Which of the following amplifier types reduces or eliminates even order harmonics?
E7B07 Which of the following is a likely result when a Class C amplifier is used to amplify a single-sideband phone signal?
E7B08 How can an RF power amplifier be neutralized?
E7B09 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?
E7B10 In Figure E7-1, what is the purpose of R1 and R2?
E7B11 In Figure E7-1, what is the purpose of R3?
E7B12 What type of amplifier circuit is shown in Figure E7-1?
E7B13 In Figure E7-2, what is the purpose of R?
E7B14 Why are switching amplifiers more efficient than linear amplifiers?
E7B15 What is one way to prevent thermal runaway in a bipolar transistor amplifier?
E7B16 What is the effect of intermodulation products in a linear power amplifier?
E7B17 Why are odd-order rather than even-order intermodulation distortion products of concern in linear power amplifiers?
E7B18 What is a characteristic of a grounded-grid amplifier?
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Group E7C Filters and 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?
E7C02 Which of the following is a property of a T-network with series capacitors and a parallel shunt inductor?
E7C03 What advantage does a Pi-L-network have over a regular Pi-network for impedance matching between the final amplifier of a vacuum-tube transmitter and an antenna?
E7C04 How does an impedance-matching circuit transform a complex impedance to a resistive impedance?
E7C05 Which filter type is described as having ripple in the passband and a sharp cutoff?
E7C06 What are the distinguishing features of an elliptical filter?
E7C07 What kind of filter would you use to attenuate an interfering carrier signal while receiving an SSB transmission?
E7C08 Which of the following factors has the greatest effect in helping determine the bandwidth and response shape of a crystal ladder filter?
E7C09 What is a Jones filter as used as part of an HF receiver IF stage?
E7C11 Which of the following is the common name for a filter network which is equivalent to two L-networks connected back-to-back with the two inductors in series and the capacitors in shunt at the input and output?
E7C12 Which describes a Pi-L-network used for matching a vacuum tube final amplifier to a 50 ohm unbalanced output?
E7C13 What is one advantage of a Pi-matching network over an L-matching network consisting of a single inductor and a single capacitor?
E7C14 Which mode is most affected by non-linear phase response in a receiver IF filter?
E7C15 What is a crystal lattice filter?
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Group E7D Power supplies and voltage regulators; Solar array charge controllers
E7D01 What is one characteristic of a linear electronic voltage regulator?
E7D02 What is one characteristic of a switching electronic voltage regulator?
E7D03 What device is typically used as a stable reference voltage in a linear voltage regulator?
E7D04 Which of the following types of linear voltage regulator usually make the most efficient use of the primary power source?
E7D05 Which of the following types of linear voltage regulator places a constant load on the unregulated voltage source?
E7D06 What is the purpose of Q1 in the circuit shown in Figure E7-3?
E7D07 What is the purpose of C2 in the circuit shown in Figure E7-3?
E7D08 What type of circuit is shown in Figure E7-3?
E7D09 What is the main reason to use a charge controller with a solar power system?
E7D10 What is the primary reason that a high-frequency switching type high voltage power supply can be both less expensive and lighter in weight than a conventional power supply?
E7D11 What circuit element is controlled by a series analog voltage regulator to maintain a constant output voltage?
E7D12 What is the drop-out voltage of an analog voltage regulator?
E7D13 What is the equation for calculating power dissipation by a series connected linear voltage regulator?
E7D14 What is one purpose of a "bleeder" resistor in a conventional unregulated power supply?
E7D15 What is the purpose of a "step-start" circuit in a high voltage power supply?
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?
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Group E7E Modulation and demodulation: reactance, phase and balanced modulators; detectors; mixer stages
E7E01 Which of the following can be used to generate FM phone emissions?
E7E02 What is the function of a reactance modulator?
E7E03 How does an analog phase modulator function?
E7E04 What is one way a single-sideband phone signal can be generated?
E7E05 What circuit is added to an FM transmitter to boost the higher audio frequencies?
E7E06 Why is de-emphasis commonly used in FM communications receivers?
E7E07 What is meant by the term baseband in radio communications?
E7E08 What are the principal frequencies that appear at the output of a mixer circuit?
E7E09 What occurs when an excessive amount of signal energy reaches a mixer circuit?
E7E10 How does a diode detector function?
E7E11 Which type of detector is used for demodulating SSB signals?
E7E12 What is a frequency discriminator stage in a FM receiver?
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Group E7F DSP filtering and other operations; Software Defined Radio Fundamentals; DSP modulation and demodulation
E7F01 What is meant by direct digital conversion as applied to software defined radios?
E7F02 What kind of digital signal processing audio filter is used to remove unwanted noise from a received SSB signal?
E7F03 What type of digital signal processing filter is used to generate an SSB signal?
E7F04 What is a common method of generating an SSB signal using digital signal processing?
E7F05 How frequently must an analog signal be sampled by an analog-to-digital converter so that the signal can be accurately reproduced?
E7F06 What is the minimum number of bits required for an analog-to-digital converter to sample a signal with a range of 1 volt at a resolution of 1 millivolt?
E7F07 What function can a Fast Fourier Transform perform?
E7F08 What is the function of decimation with regard to digital filters?
E7F09 Why is an anti-aliasing digital filter required in a digital decimator?
E7F10 What aspect of receiver analog-to-digital conversion determines the maximum receive bandwidth of a Direct Digital Conversion SDR?
E7F11 What sets the minimum detectable signal level for an SDR in the absence of atmospheric or thermal noise?
E7F12 What digital process is applied to I and Q signals in order to recover the baseband modulation information?
E7F13 What is the function of taps in a digital signal processing filter?
E7F14 Which of the following would allow a digital signal processing filter to create a sharper filter response?
E7F15 Which of the following is an advantage of a Finite Impulse Response (FIR) filter vs an Infinite Impulse Response (IIR) digital filter?
E7F16 How might the sampling rate of an existing digital signal be adjusted by a factor of 3/4?
E7F17 What do the letters I and Q in I/Q Modulation represent?
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Group E7G Active filters and op-amp circuits: active audio filters; characteristics; basic circuit design; operational amplifiers
E7G01 What is the typical output impedance of an integrated circuit op-amp?
E7G02 What is the effect of ringing in a filter?
E7G03 What is the typical input impedance of an integrated circuit op-amp?
E7G04 What is meant by the term op-amp input offset voltage?
E7G05 How can unwanted ringing and audio instability be prevented in a multi-section op-amp RC audio filter circuit?
E7G06 Which of the following is the most appropriate use of an op-amp active filter?
E7G07 What magnitude of voltage gain can be expected from the circuit in Figure E7-4 when R1 is 10 ohms and RF is 470 ohms?
E7G08 How does the gain of an ideal operational amplifier vary with frequency?
E7G09 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 DC is applied to the input?
E7G10 What absolute voltage gain can be expected from the circuit in Figure E7-4 when R1 is 1800 ohms and RF is 68 kilohms?
E7G11 What absolute voltage gain can be expected from the circuit in Figure E7-4 when R1 is 3300 ohms and RF is 47 kilohms?
E7G12 What is an integrated circuit operational amplifier?
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Group E7H Oscillators and signal sources: types of oscillators; synthesizers and phase-locked loops; direct digital synthesizers; stabilizing thermal drift; microphonics; high accuracy oscillators
E7H01 What are three oscillator circuits used in Amateur Radio equipment?
E7H02 Which describes a microphonic?
E7H03 How is positive feedback supplied in a Hartley oscillator?
E7H04 How is positive feedback supplied in a Colpitts oscillator?
E7H05 How is positive feedback supplied in a Pierce oscillator?
E7H06 Which of the following oscillator circuits are commonly used in VFOs?
E7H07 How can an oscillator’s microphonic responses be reduced?
E7H08 Which of the following components can be used to reduce thermal drift in crystal oscillators?
E7H09 What type of frequency synthesizer circuit uses a phase accumulator, lookup table, digital to analog converter, and a low-pass anti-alias filter?
E7H10 What information is contained in the lookup table of a direct digital frequency synthesizer?
E7H11 What are the major spectral impurity components of direct digital synthesizers?
E7H12 Which of the following must be done to insure that a crystal oscillator provides the frequency specified by the crystal manufacturer?
E7H13 Which of the following is a technique for providing highly accurate and stable oscillators needed for microwave transmission and reception?
E7H14 What is a phase-locked loop circuit?
E7H15 Which of these functions can be performed by a phase-locked loop?
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