1. Amateur Extra Q & A Study Pool
Quiz # 5
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2.  1.    Which of the following factors has the greatest effect in helping determine the bandwidth and response shape of a crystal ladder filter? E6E05
A. The relative frequencies of the individual crystals
B. The DC voltage applied to the quartz crystal
C. The gain of the RF stage preceding the filter
D. The amplitude of the signals passing through the filter

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5. 2. Where on the load line of a Class A common emitter amplifier would bias normally be set? E7B03
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

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8.    3.  Which of the following amplifier types reduces or eliminates even-order harmonics?
E7B05
A. Push-push
B. Push-pull
C. Class C
D. Class AB

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11. 4. How can a vacuum-tube power amplifier be neutralized? E7B07
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

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14.     5. Why are third-order intermodulation distortion products of particular concern in linear power amplifiers? E7B16
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

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17.   6. How are the capacitors and inductors of a low-pass filter pi-network arranged between the network's input and output? E7C01
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

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20. 7.   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? E7C03
A. Greater harmonic suppression
B. Higher efficiency
C. Lower losses
D. Greater transformation range

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23. 8. How does a network transform a complex impedance into a resistive impedance? E7C04
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

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26. 9. What kind of digital signal processing audio filter might be used to remove unwanted noise from a received SSB signal? E7C08
A. An adaptive filter
B. A crystal-lattice filter
C. A Hilbert-transform filter
D. A phase-inverting filter

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29. 10. What is one characteristic of a linear electronic voltage regulator? E7D01
A. It has a ramp voltage as its output
B. It eliminates the need for a pass transistor
C. The control device 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

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32. 11. What type of circuit is shown in Figure E7-3? E7D08
A. Switching voltage regulator
B. Grounded emitter amplifier
C. Linear voltage regulator
D. Emitter follower

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35. 12. What is the purpose of a "step-start" circuit in a high-voltage power supply? E7D15
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

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38. 13. What is the fundamental principle of a phase modulator? E7E03
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

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41. 14. What are the principal frequencies that appear at the output of a mixer circuit? E7E08
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 and times the input frequency

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44. 15. What is the process of detection? E7E10
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

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47. 16. What are the advantages of using an op-amp instead of LC elements in an audio filter? E7G03
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

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50. 17. Which of the following is the most appropriate use of an op-amp RC active filter? E7G07
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

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53. 18. What is an operational amplifier? E7G14
A. A high-gain, direct-coupled differential amplifier whose characteristics are determined by components external to the amplifier
B. A high-gain, direct-coupled audio amplifier whose characteristics are determined by components external to the amplifier
C. An amplifier used to increase the average output of frequency modulated amateur signals to the legal limit
D. A program subroutine that calculates the gain of an RF amplifier

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56. 19. What condition must exist for a circuit to oscillate? E7H02
A. It must have at least two stages
B. It must be neutralized
C. It must have positive feedback loop with a gain greater than 1
D. It must have negative feedback sufficient to cancel the input signal

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59. 20. How is positive feedback supplied in a Colpitts oscillator? E7H04
A. Through a tapped coil
B. Through link coupling
C. Through a capacitive divider
D. Through a neutralizing capacitor

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62. 21. What type of frequency synthesizer circuit uses a stable voltage-controlled oscillator, programmable divider, phase detector, loop filter and a reference frequency source? E7H09
A. A direct digital synthesizer
B. A hybrid synthesizer
C. A phase-locked loop synthesizer
D. A diode-switching matrix synthesizer

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65. 22. Why is a stable reference oscillator normally used as part of a phase locked loop (PLL) frequency synthesizer? E7H18
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

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