Self-Test
& Supply the missing word(s) in each statement.
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?
True or false. Speech processing may be done on the RF signal or the audio signal.
No comments:
Post a Comment