This is the Self-test in Chapter 6: Radio Transmitters from the book COMMUNICATIONS ELECTRONICS by Louis E. Frenzel. If you are looking for a reviewer in Communications Engineering this will definitely help. I can assure you that this will be a great help in reviewing the book in preparation for your Board Exam. Make sure to familiarize each and every questions to increase the chance of passing the ECE Board Exam.
Start Practice Exam Test Questions
Direction: Either Supply the missing word(s) in each statement or Choose the letter that best answers each question.
1. The simplest transmitter is a(n) _____ circuit.
2. Information sent in the form of coded dots and dashes is called _____ transmission and is abbreviated _____.
3. Fixed-frequency or channel operation of a transmitter is obtained by using a(n) _____.
4. An amplifier that isolates the carrier oscillator from other transmitter amplifiers is known as a _____ amplifier.
5. Intermediate power amplifier stages in a transmitter are commonly referred to as _____.
6. The output RF power amplifier in a transmitter is sometimes called the _____.
7. Audio circuits that prevent excessive signal bandwidth and over modulation are called _____. circuits.
8. In an PM transmitter, special amplifiers called _____ are used to increase the carrier frequency and deviation to the desired output values.
9. In an SSB transmitter, the final output frequency is usually produced by a(n) _____ circuit before being amplified.
10. The power level of SSB signals must be increased by _____ amplifiers to prevent distortion.
11. Frequency-modulated signals use _____ amplifiers for power amplification.
12. Linear power amplifiers are used to raise the power level of _____ and _____ signals.
13. A _____ power amplifier is used to increase the power level of an FM signal.
14. Linear power amplifiers operate class _____ and _____.
15. A Class A Transistor amplifier has an efficiency of 50 percent. The output power is 27W. The power dissipated in the transistor is _____ W.
16. Class A amplifiers conduct for _____ degrees of a sine wave input.
17. The cause of self-oscillation in a transistor RF amplifiers is _____.
18. Self-oscillation in an RF amplifier that does not occur at the tuned frequency of the amplifier is called _____.
19. Self-oscillation of an RF amplifier can be eliminated by the process of _____.
20. True or false. Elimination of self-oscillation can be accomplished with either a feedback inductor or a capacitor.
21. Combining a feedback capacitor with the internal capacitance of the transistor forms a(n) _____ circuit which is used to cancel the self-oscillation.
22. True or false. With no input, a class B amplifier does not conduct.
23. Class B RF power amplifiers normally used a(n) _____ configuration.
24. A class C amplifier conducts for approximately _____ degrees to _____ degrees of the input signal.
25. In a class C amplifier collector current flows in the form of _____.
26. In a class C amplifier, a complete sinusoidal output signal is produced by a(n) _____.
27. The efficiency of a class C amplifier is in the range of _____ to _____ percent.
28. The tuned circuit in the collector of a class C amplifier acts as a filter to eliminate _____.
29. A class C amplifier whose output tuned circuit resonates at some integer multiple of the input frequency is called a(n) _____.
30. Frequency multipliers with factors of 2, 3, 4, and 5 are cascaded. The input is 1.5 MHz. The output is _____ MHz.
31. A class C amplifier has a de supply voltage of 28 V and an average collector current of 1.8 A. The power input is _____ W.
32. Maximum power transfer occurs when the generator impedance _____ the load impedance.
33. A commonly used two-element (LC) circuit called a(n) _____ is widely used for impedance matching.
34. List the two popular types of three element (LC) matching networks.
35. Most impedance-matching networks are _____ filters, so they eliminate harmonies.
36. The main advantage of pi and T networks over the L network is that the circuit _____ can be chosen.
37. 37 True or false. Most impedance-matching networks are made adjustable (tunable).
38. Calculate the L network components to match a 3-Ω internal resistance in series with an internal inductance of 19 nH to a 72-Ω load impedance in parallel with a stray capacitance of 32 pF at a frequency of 18 MHz.
39. Calculate the components of an LCC T network to match a 4-Ω internal resistance to a 52-Ω load at 72 MHz. Assume a Q of 12.
40. A transformer has 6 turns on the primary and 18 turns on the secondary. If the generator (source) impedance is 50Ω, the load impedance should be _____ Ω.
41. A transformer must match a 200 generator a 50-Ω load. The turns ratio must be _____.
42. A single-winding transformer is known as a(n) _____.
43. A doughnut-shaped powdered-iron core widely used to make RF transformers and inductors is called a(n) _____.
44. An RF transformer with a 1:1 turns ratio called a(n) _____ is connected in Ii special way to provide 1:4 or 4:1 impedance matching.
45. Untuned RF transformers permit _____ operation over a wide frequency range.
46. The two techniques used in speech processing are _____ and _____.
47. Name the two primary purposes of speech processing.
48. A diode _____ circuit is frequently used to restrict voice signal amplitude.
49. Name the two main purposes of a low-pass filter in a speech-processing circuit.
50. Over modulation in an AM transmitter causes distortion and out-of-band operation which is referred to as _____.
51. Audio compression is achieved by controlling the _____ of an audio amplifier.
52. Audio compression is used to increase the average _____ in an AM or SSB signal.
53. _____ and _____ circuits are used in a speech compressor to create a dc feedback control signal.
54. The gain of a transistor can be controlled by varying the _____.
55. The process of adjusting the amplification of a signal based on its amplitude is known as _____.
56. In an audio compressor, do low-level signals receive more or less amplification?
57. True or false. Speech processing may be done on the RF signal or the audio signal.