Frenzel Self-test in Communications Receivers - Answers

Answers key for Frenzel Self-test in Communications Receivers from the book COMMUNICATIONS ELECTRONICS by Louis E. Frenzel. Make sure to familiarize each and every questions.

Answers for Frenzel Self-test in Communications Receivers

Below are the answers key for Frenzel Self-test in Chapter 7: Communications Receivers from the book COMMUNICATIONS ELECTRONICS by Louis E. Frenzel. Make sure to familiarize each and every questions to increase the chance of passing the ECE Board Exam.

1. selectivity

2. increase

3. narrow

4. true (resonant step-up)

5. increase(narrower bandwidth)

6. sidebands

7. 5

8. 0.53 MHz or 530 kHz (fr = 10.6 MHz, XL = 200 , Q = 20)

9. 9.95, 10.05

10. 1333.3

11. decreased

12. 2.4

13. sensitivity

14. tuned radio frequency

15. superheterodyne

16. intermediate frequency

17. local oscillator

18. IF amplifier

19. automatic gain control

20. signal or input, local oscillator

21. IF amplifier

22. c (low)

23. Image

24. 3.5

25. selectivity

26. 28

27. true

28. mixer

29. Intermediate frequency

30. 9,600

31. industrial, atmospheric, and space

32. thermal agitation, shot noise, transit-time noise

33. extraterrestrial or space

34. lightning

35. automobiles, motors, generators, fluorescent lights

36. thermal agitation

37. decibels

38. high

39. increase

40. white, Johnson

41. decrease

42. 1.36

43. shot, transit-time

44. false

45. true

46. noise figure

47. microwave

48. 48.464

49. 49. distortion

50. 50. high

51. RF amplifier, mixer

52. true

53. gain, selectivity, noise

54. MESFET or GASFET, gallium arsenide

55. IF

56. tuned circuits

57. mutual inductance

58. under, over, optimum, critical

59. limiter

60. cutoff, saturation

61. collector current

62. 100

63. automatic gain control

64. IF

65. rectifier, IF amplifier or detector

66. decrease

67. increase

68. constant-current source

69. control gate

70. automatic volume control

71. diode detector

72. reduced

73. local oscillator

74. demodulator

75. voltage-variable capacitor

76. squelch

77. audio, noise

78. tone, squelch

79. SSB, CW

80. the ceramic filter FIL1

81.As the pot arm voltage goes more positive, the reverse bias across D1 increases, thus decreasing its capacitance and the overall capacitance of D1 in series with C14; this in turn increases the local oscillator frequency.

82. volume R2 and squelch R3

83. U2, the MC1350 IF amplifier IC

84. The squelch is signal derived

85. With no BFO, the receiver cannot receive CW or SSB.

86. The gain increases.

87. pin 5 of the U3-b op amp

88.10.7 MHz injected to the ceramic filter FIL1

89. U2, the MC1350 IC, would lose supply voltage at pin 2.

90. A digital counter could be connected to monitor the local oscillator output signal at pin 6 or 7 of the NE602 mixer IC. This would read the local oscillator frequency, which is 10.7 MHz higher than the actual input signal frequency. Therefore, the counter would have to be preset to a value that is 10.7 MHz less than zero count. In this way, the IF value would effectively be subtracted from the input count to read the correct frequency. Assume that the counter is set up to count four digits, 000.0. The counter is preset to 100.0 - 10.7= 89.3, and the input signal frequency is 118 MHz. The local oscillator is tuned to 118 + 10.7 = 128.7 MHz. The counter counts 10.7 to reach 000.0 and then counts 118 more to display a final value of 118.0.

91. power supply

92. crystal filter, local oscillators

93. frequency synthesizer

94. phase-locked loop

95. frequency division ratio

96. 2.86, 10

97. mixer

98. LO for first mixer, LO for second mixer, transmitter

Complete List of Self-test and Reviewers in Communications Electronics


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