Measurement of Hydraulic Conductivity of Saturated Porous Materials Using a Flexible Wall Permeameter 1
9. Procedure
1. Which of the following is NOT produced when two sine waves are combined through a nonlinear device?
a. Components of each of the two original frequencies b. Components at the sum and difference frequencies c. Harmonics of the two original frequencies d. ac level
Answer: d
2. Which of the following is considered a nonlinear device?
a. Resistor b. Capacitor c. Potentiometer d. Transistor Answer: d
3. Which of the following modulation techniques is the most economical?
a. High-level b. Low-level c. Medium-level d. Ultra low-level Answer: a
4. If the % modulation of an AM transmitter is 60% and the unmodulated antenna current is 10 A, what is the modulated current?
a. 11 A b. 14 A c. 5 A d. 13 A Answer: a
5. If the carrier transmits 12 kW, what is the modulated power from Problem 4?
a. 12 kW b. 10 kW c. 14 kW d. 16 kW Answer: c
TEST ITEM FILE – Chapter 2
6. The reason modulation is used in electronic communication is:
a. Since all intelligence signals occur at approximately the same frequency, there would be catastrophic interference problems if these frequencies were used.
b. Audio frequency radio waves do not propagate long distances very reliably.
c. Efficient transmission and reception of radio waves are not possible unless extremely large antennas are used.
d. All of the above.
Answer: d
7. Which of the following is not created by nonlinear mixing?
a. The original two frequencies
b. Harmonics of the sum and difference frequencies c. The sum and difference of the two original frequencies d. dc (0 Hz)
Answer: b
8. A 2 kHz sinewave is mixed with a 1.5 MHz carrier sinewave through a nonlinear device. Which frequency is not present in the output signal?
a. 3 MHz b. 1.502 MHz c. 3.004 MHz d. 1.498 MHz Answer: c
9. A 2.5 MHz carrier is modulated by a music signal that has frequency components ranging from 100 Hz to 5 kHz. What is the range of frequencies generated for the upper sideband?
a. 2.5 MHz to 2.505 MHz
a. results when the modulation index exceeds unity.
b. is undesirable because it produces sideband splatter.
c. causes the AM signal to become distorted so that the receiver cannot produce a clean replica of the original intelligence signal.
d. all of the above.
Answer: d
TEST ITEM FILE – Chapter 2
Figure 2-1
11. In Figure 2-1, A is 220 mVp-p and B is 350 mVp-p. The percent modulation of the AM signal is:
a. 62.9%
b. 1.59%
c. 22.8%
d. 4.38%
Answer: c
12. In Figure 2-1, Ei is 530 mV peak and Ec is 780 mV peak. The percent modulation of the AM signal is:
a. 67.9%
b. 32.1%
c. 19.1%
d. 14.7%
Answer: a
13. In Figure 2-1, A is 1.5Vp-p and B is 3.3Vp-p. If the carrier signal is set at 1.2V peak, the intelligence signal is:
a. 3.2V peak.
b. 0.55V peak.
c. 0.9V peak.
d. 0.45V peak.
Answer: d
TEST ITEM FILE – Chapter 2
14. The total output power of an AM transmitter that is being operated at 50% modulation is measured to be 1800 watts. What is the carrier power?
a. 1440 watts b. 1600 watts c. 900 watts d. 2025 watts
Answer: b
15. A 250W carrier is to be modulated at an 85% modulation level. What is the total transmitted power?
16. An AM broadcast station operates at its maximum allowed output power of 80W at a percent modulation of 60%. What is the upper sideband power?
a. 6.1 watts b. 18.47 watts c. 9.23 watts d. 12.2 watts Answer: a
17. The antenna current of an AM transmitter is 5A when it is not modulated. It increases to 6A when it is modulated. Its modulation index expressed as a percentage is:
a. 83.3%
b. 63.2%
c. 69.4%
d. 93.8%
Answer: d
18. An intelligence signal is amplified by a 65% efficient amplifier before being combined with a 250W carrier to generate an AM signal. If it is desired to operate at 100% modulation, what must be the dc input power to the final intelligence signal amplifier?
a. 384.6W
b. 192.3W
c. 162.5W
d. 83.3W
Answer: b
TEST ITEM FILE – Chapter 2
19. High-level modulation is used:
a. when the intelligence signal is added to the carrier at the last possible point before the transmitting antenna.
b. in high-power applications such as standard radio broadcasting.
c. when the transmitter must be made as power efficient as possible.
d. all of the above.
Answer: d
20. The process of neutralization is:
a. placing a negative feedback capacitor in an RF amplifier to reduce the tendency for self-oscillation.
b. a technique for filtering out all of the undesired frequencies produced by mixing action in a nonlinear amplifier except for the carrier, sum, and difference frequencies.
c. the process of adjusting the tank circuit so that the transmitter produces the proper output frequency.
d. the process of adjusting the percent modulation to its desired level in a modulator stage.
Answer: a
Figure 2-2
21. The transmitter scheme in Figure 2-2 is set up for:
a. high-level modulation.
b. low-level modulation.
c. medium-level modulation.
Answer: a
22. In Figure 2-2, the audio amplifier and modulator stages:
a. are biased Class A or B for low distortion.
b. are biased Class A or B for high power efficiency.
c. are biased Class C for good mixing action.
d. are biased Class C for high power efficiency.
TEST ITEM FILE – Chapter 2
23. In Figure 2-2, which stages contain "tuned" amplifiers?
a. stages b and c b. stages e and f c. stages c and f d. stages b and f Answer: a
24. In Figure 2-2, the AM waveform is created in:
a. stage b b. stage c c. stage e d. stage f
Answer: b
Figure 2-3
25. The transmitter scheme in Figure 2-3 is set up for:
a. high-level modulation.
b. low-level modulation.
d. medium-level modulation.
Answer: b
26. In Figure 2-3, which stages contain tuned amplifiers?
a. stages b, c, and d b. stages b and f c. stages c and f d. stages e and f Answer: a
TEST ITEM FILE – Chapter 2
27. In Figure 2-3, the AM waveform is created in:
a. stage b.
b. stage c.
c. stage d.
d. stage f.
Answer: a
28. In Figure 2-3, which stages use linear amplification?
a. stages b, c, and d b. stages c, d, and f c. stages b and f d. stages b and c
Answer: b
29. The O.T.A. is:
a. a special type of op amp used to create an AM signal.
b. an operational transconductance amplifier.
c. a linear integrated circuit that creates AM with an absolute minimum of design considerations.
d. all of the above.
Answer: d
30. The last stage of intelligence amplification before mixing with the carrier occurs in:
a. the modulator.
b. the modulated amplifier.
c, the buffer.
d. the RF linear amplifier.
Answer: a
TEST ITEM FILE – Chapter 2
Figure 2-4a
31. In Figure 2-4a, the trapezoidal display indicates:
a. improper bias or low carrier signal power.
b. proper in-phase trapezoidal pattern for typical AM signal.
c. poor linearity of the modulator.
d. lack of an intelligence signal.
Answer: b
Figure 2-4b
32. In Figure 2-4b, the trapezoidal display indicates:
a. improper bias or low carrier signal power.
b. proper in-phase trapezoidal pattern for typical AM signal.
c. poor linearity of the modulator.
d. lack of an intelligence signal.
Answer: d
TEST ITEM FILE – Chapter 2
Figure 2-4c
33. In Figure 2-4c, the trapezoidal display indicates:
a. improper bias or low carrier signal power.
b. proper in-phase trapezoidal pattern for typical AM signal.
c. poor linearity of the modulator.
d. lack of an intelligence signal.
Answer: c
Figure 2-4d
34. In Figure 2-4d, the trapezoidal display indicates:
a. improper bias or low carrier signal power.
b. proper in-phase trapezoidal pattern for typical AM signal.
c. poor linearity of the modulator d. lack of an intelligence signal.
Answer: a
TEST ITEM FILE – Chapter 2
35. In Figure 2-5, the carrier frequency is shown as being 50.003 MHz. The frequencies of the spurs on either side of the carrier are:
Figure 2-5 a. approximately 24 kHz away from the carrier.
b. 48.0034 MHz and 52.0034 MHz.
c. approximately 15 dB below the carrier level.
d. approximately 14 dB above the noise floor.
e. none of the above.
Answer: c
36. The equation defining the AM envelope is a. e =(Ec +Ei sin ωit) sin ωit
37. The result of the trigonometric identity (sin x)( sin y) is a. cos(x-y) – cos(x+y)
38. Determine the side frequency voltage if the modulation index is 70%and the carrier amplitude is 50V.
a. 25
39. Determine the frequency of the AM carrier shown in Figure 2-6.
a. 1 MHz
TEST ITEM FILE – Chapter 2
40. The typical output impedance for an RF transmitter is a. 75 Ω
b. 50 Ω c. 8 Ω d. 16 Ω
e. none of the above Answer: b
TEST ITEM FILE - CHAPTER 3 AMPLITUDE MODULATION: RECEPTION
1. Which of the following is not an advantage of a synchronous detection?
a. Low distortion
b. Eliminate diagonal clipping
c. Greater ability to follow fast-modulated signals d. Ability to produce gain
Answer: b
2. The mixer is often referred to as:
a. RF amplifier.
b. oscillator generator.
c. second detector.
d. first detector.
Answer: d
3. Varactor diodes are used for tuning by:
a. capacitance adjustment through a reverse bias diode.
b. capacitance adjustment through forward bias.
c. temperature compensation of diodes.
d. all of the above.
Answer: a
4. In a varactor diode, as voltage increases, capacitance:
a. increases.
b. stays the same.
c. decreases.
d. none of the above.
Answer: c
5. The only roadblock to having complete receivers on a chip aside from station selection and volume controls is:
a. limiting factors of tuned circuits.
b. local oscillator.
c. mixer circuits.
d. IF amplifier.
Answer: a
TEST ITEM FILE - Chapter 3
6. The radio receiver that simply consists of an RF amplifier, detector, and audio amplifier is known as:
a. a superheterodyne receiver.
b. a TRF receiver.
c. a selective receiver.
d. a sensitive receiver.
Answer: b
7. A receiver’s sensitivity is:
a. the extent to which a receiver is capable of differentiating between the desired signal and other signals.
b. its ability to drive the output speaker to an acceptable level.
c. the ability of the receiver to demodulate a modulated signal.
d. the ability of a receiver to attenuate noise signals.
Answer: b
8. A receiver’s selectivity is:
a. the extent to which a receiver is capable of differentiating between the desired signal and other signals.
b. its ability to drive the output speaker to an acceptable level.
c. the ability of the receiver to demodulate a modulated signal.
d. the ability of a receiver to attenuate noise signals.
Answer: a
9. If a receiver is overly selective:
a. too much noise is picked up and amplified by the receiver.
b. only part of the bandwidth of the AM signal is amplified, causing some of the sideband information to be lost and distortion results.
c. the tank circuits within the tuned amplifiers have insufficient Q.
d. when the volume control is turned up to maximum, the desired station is very weak.
Answer: b
10. If a receiver is underselective:
a. only part of the bandwidth of the AM signal is amplified, causing some of the sideband information to be lost and distortion results.
b. the tank circuits within the tuned amplifiers have too high a Q.
c. when the volume control is turned up to maximum, the desired station is very weak.
d. more than one radio station on different frequencies may be picked up by the receiver at the same time.
Answer: d
TEST ITEM FILE - Chapter 3
11. A TRF receiver is to be designed with a single tuned circuit using an 8.2 uH inductor. If the frequency is to be tuned from 55 kHz to 1600 kHz, find the BW that results at 550 kHz if there is exactly 10 kHz BW at a frequency of 1050 kHz.
a. 105 kHz b. 15.24 kHz c. 5.24 kHz d. 10 kHz Answer: c
12. The diode detector:
a. is one of the simplest and most effective AM detectors.
b. consists of a nonlinear diode and low-pass filter.
c. is sometimes referred to as an envelope detector.
d. all of the above.
Answer: d
13. Which is not an advantage of diode detectors?
a. Power absorbed from the tuned circuit by the diode detector reduces the Q of the tuned circuit.
b. They develop a readily usabledc voltage for automatic gain control circuits.
c. They are highly efficient.
d. Distortion decreases as the amplitude of the AM signal increases.
Answer: a
14. Diagonal clipping:
a. occurs if the time constant of the low-pass filter is too large compared to the period of the RF waveform.
b. is a type of distortion that occurs with diode detectors.
c. is characterized by having the capacitor voltage not follow the full changes of the envelope of the AM waveform.
d. all of the above.
Answer: d
15. Synchronous detectors:
a. are often called product detectors.
b. offer low distortion compared to diode detectors.
c. have the ability to provide gain.
d. all of the above.
Answer: d
TEST ITEM FILE - Chapter 3
16. The superheterodyne receiver design is superior to the TRF design:
a. since it allows for a constant selectivity over the entire tuning range of the receiver.
b. since it always uses synchronous detectors instead of diode detectors.
c. since it uses many RF amplifier stages before the RF signal is mixed with the local oscillator signal.
d. all of the above.
Answer: a
17. An AM signal having a carrier frequency of 560 kHz is to be mixed with a local oscillator signal at a frequency of 1035 kHz. What does the output of the IF amplifier consist of?
a. a 455 kHz carrier b. a 475 kHz sinewave c. a 475 kHz AM signal
d. the original intelligence signal Answer: c
19. In Figure 3-1, the output signal of stage (e) is:
a. an AM signal with a carrier frequency of 490 kHz.
b. an AM signal with a carrier frequency of 1850 kHz.
c. a 490 kHz sinewave.
d. an 1850 kHz sinewave.
Answer: d
20. In Figure 3-1, the output signal of stage (d) is:
a. an AM signal with a carrier frequency of 490 kHz.
b. an AM signal with a carrier frequency of 1360 kHz.
c. a 490 kHz sinewave.
d. a 1 kHz sinewave.
Answer: d
TEST ITEM FILE - Chapter 3
21. In Figure 3-1, the output of stage (a) is:
a. an AM signal with a carrier frequency of 1360 kHz.
b. an AM signal with a carrier frequency of 1850 kHz.
c. a 490 kHz sinewave.
d. an 1850 kHz sinewave.
Answer: a
22. In Figure 3-1, the output signal of stage (c) is:
a. an AM signal with a carrier signal of 490 kHz.
b. an AM signal with a carrier frequency of 1360 kHz.
c. a 490 kHz sinewave.
d. a 1 kHz sinewave.
Answer: a
23. In Figure 3-1, the receiver design is known as:
a. regenerative.
b. superheterodyne.
c. TRF.
d. synchronous.
Answer: b
24. In Figure 3-1, the stage sometimes referred to as the first detector is:
a. stage a.
b. stage b.
c. stage c.
d. stage d.
Answer: b
25. In Figure 3-1, the stages that contain tuned circuits are:
a. stages a, b and d.
b. stages a, b and c.
c. stages a, d and e.
d. stages a, c and d.
Answer: b
26. In Figure 3-1, the stages that must contain nonlinear devices are:
a. stages a, b and c.
b. stages a and e.
c. stages b and d.
d. stages b and c.
Answer: c
TEST ITEM FILE - Chapter 3
27. A padder capacitor:
a. is placed in series with the tank inductor to provide tracking at the low end of a large frequency band.
b. is placed in parallel with each section of the ganged capacitors of the tank to provide tracking at the high end of a large frequency band.
c. is placed in an RF amplifier to provide for proper neutralization.
d. is placed in a tank circuit to provide for electronic tuning.
Answer: a
28. A trimmer capacitor:
a. is placed in series with the tank inductor to provide tracking at the low end of a large frequency band.
b. is placed in parallel with each section of the ganged capacitor of the tank to provide tracking at the high end of a large frequency band.
c. is placed in an RF amplifier to provide for proper neutralization.
d. is placed in a tank circuit to provide for electronic tuning.
Answer: b 29. A varicap:
a. is placed in series with the tank inductor to provide tracking at the low end of a large frequency band.
b. is placed in parallel with each section of the ganged capacitors of the tank to provide tracking at the high end of a large frequency band.
c. is placed in an RF amplifier to provide for proper neutralization.
d. is placed in a tank circuit to provide for electronic tuning.
Answer: d
31. Image frequency rejection on a standard AM broadcast band receiver is not a major problem since:
a. the image frequency is not close to the IF frequency.
b. the image frequency is not close to the LO frequency.
c. the image frequency is not produced by mixing action.
d. the image frequency is so far away from the RF amplifier stage’s tuned frequency.
Answer: d
TEST ITEM FILE - Chapter 3
32. Which of the following is not a major benefit of using RF amplifier stages in superheterodyne receiver design?
a. improved image frequency rejection b. larger frequency tuning range
c. more gain resulting in improved sensitivity d. improved noise characteristics
Answer: b
33. Which of the following is not an advantage of FETs over BJTs in RF amplifier usage?
a. Their input impedance does not load down the Q of the circuit preceding the FET stage.
b. The availability of dual gate FETs provides an isolated injection point for the AGC.
c. Their input/output square-law relationship allows for lower distortion levels.
d. They have improved image frequency rejection.
Answer: d
34. An autodyne mixer is:
a. a stage that provides the mixing and generates the LO at the same time.
b. a mixer that uses a dual-gate FET.
c. a mixer that automatically provides for AGC action.
d. a stage that mixes the LO with the AM signal without the use of a transistor.
Answer: a
35. In a superheterodyne receiver the bulk of the receiver’s sensitivity and selectivity is due to the:
a. RF amplifier stages.
b. converter stages.
c. IF amplifier stages.
d. local oscillator.
Answer: c
36. Double conversion is:
a. a receiver design that uses two superheterodyne receivers to receive a weak signal.
b. a technique used to reduce image frequency problems in a superheterodyne receiver.
c. a technique used to solve the TRF tuning problems.
d. a method that ensures that a superheterodyne receiver does not break into oscillations due to stray positive feedback.
Answer: b
TEST ITEM FILE - Chapter 3
37. The circuit of Figure 3-2 is an example of:
a. an RF mixer, local oscillator, and IF filter.
b. an autodyne mixer.
c. a receive converter.
d. all of the above.
Answer: d
38. In Figure 3-2, the tank circuit made up of L1 and C1 is tuned at:
a. the IF frequency.
b. the LO frequency.
c. the RF carrier frequency.
d. the image frequency.
Answer: c
39. In Figure 3-2, the tank circuit made up of L4 and C4 is tuned at:
a. the IF frequency.
b. the LO frequency.
c. the RF carrier frequency.
d. the image frequency.
Answer: b
40. In Figure 3-2, the tank circuit made up of L5 and C5 is tuned at:
a. the IF frequency.
b. the LO frequency.
c. the RF carrier frequency.
d. the image frequency.
TEST ITEM FILE - Chapter 3
41. In Figure 3-2, the purpose of C3 is:
a. to determine the frequency of oscillation of the LO.
b. to couple the local oscillator frequency from the tank circuit to be amplified by Q1.
c. to act as a bypass capacitor for R3.
d. to neutralize the RF amplifier stage.
Answer: b
42. The AGC control voltage:
a. is actually the dc voltage component produced by the mixing action in the AM demodulator stage.
b. varies as the signal strength of the received signal varies.
c. is a negative feedback voltage.
d. is produced by an RC circuit having a much larger time constant than that of the detector.
e. all of the above.
Answer: e
Q1 T1 Q2 T2 Q3 T3 Q4
L1
L4
43. In Figure 3-3, the tank circuit made up of L1, A, and B is tuned to:
a. the LO frequency.
b. the RF carrier frequency.
c. the IF frequency.
d. the image frequency.
Answer: b
TEST ITEM FILE - Chapter 3
44. In Figure 3-3, the tank circuit made up of L4, C, and D is tuned to:
a. the LO frequency.
b. the RF carrier frequency.
c the IF frequency.
d. the image frequency.
Answer: a
45. In Figure 3-3, the tank circuit inside of T1 is tuned to:
a. the LO frequency.
b. the RF carrier frequency.
c the IF frequency.
d. the image frequency.
Answer: c
46. In Figure 3-3, the transistor Q1 is used as:
a. the nonlinear device in an RF mixer stage.
b. the active part of an RF amplifier.
c. the active part of an LO stage.
d. all of the above.
Answer: d
47. In Figure 3-3, the transistor Q2 is used as:
a. an RF mixer stage transistor.
b. an IF amplifier stage transistor.
c. a detector transistor.
d. an audio amplifier stage transistor.
Answer: b
48. In Figure 3-3, the transistor Q3 is used as:
a. an RF mixer stage transistor.
b. an IF amplifier stage transistor.
c. a detector transistor.
d. an audio amplifier stage transistor.
Answer: b
49. In Figure 3-3, the transistor Q4 is used as:
a. an RF mixer stage transistor.
b. an IF amplifier stage transistor.
c. a detector transistor.
d. an audio amplifier stage transistor.
TEST ITEM FILE - Chapter 3
50. In Figure 3-3, the AM demodulation is accomplished by:
a. transistor - Q3.
b. diode - E1.
c. diode - E2.
d. transistor - Q4.
Answer: c
51. In Figure 3-3, the filter that produces the AGC voltage consists of:
a. R11 and C11.
b. R5 and C4.
c. R11 and C12.
d. R10 and C10.
Answer: b
52. In Figure 3-3, the inductors L1 and L2 function as:
a. an IF transformer.
b. a loopstick antenna.
c. part of the local oscillator.
d. a nonlinear mixer.
Answer: b
53. In Figure 3-3, the transformer, T3, is tuned to:
a. the intelligence frequencies.
b. the RF carrier frequency of the received station.
c. the IF frequency.
d. the local oscillator frequency.
Answer: c
54. In Figure 3-3, the selectivity is accomplished by:
a. T1, T2, and T3.
a. an auxillary AGC diode.
b. a mixer diode.
c. an AM detector diode.
d. an IF amplifier diode.
Answer: a
TEST ITEM FILE - Chapter 3
56. In Figure 3-3, the volume is controlled by adjusting:
56. In Figure 3-3, the volume is controlled by adjusting: