CHAPTER 2 VIDEO AND RF AMPLIFIERS

2-1 CHAPTER 2 VIDEO AND RF AMPLIFIERS LEARNING OBJECTIVES Upon completion of this chapter, you will be able to: 1. Define the term "bandwidth of an amplifier." 2. Determine the upper and lower frequency limits of an amplifier from a frequency-response curve. 3. List the factors that limit frequency response in an amplifier. 4. List two techniques used to increase the high-frequency response for a video amplifier. 5. State one technique used to increase the low-frequency response of a video amplifier. 6. Identify the purpose of various components on a schematic of a complete typical video amplifier circuit. 7. State the purpose of a frequency-determining network in an rf amplifier. 8. State one method by which an rf amplifier can be neutralized. 9. Identify the purpose of various components on a schematic of a complete typical rf amplifier. INTRODUCTION In this chapter you will be given information on the frequency response of amplifiers as well as specific information on video and rf amplifiers. For all practical purposes, all the general information you studied in chapter 1 about audio amplifiers will apply to the video and rf amplifiers which you are about to study. You may be wondering why you need to learn about video and rf amplifiers. You need to understand these circuits because, as a technician, you will probably be involved in working on equipment in which these circuits are used. Many of the circuits shown in this and the next chapter are incomplete and would not be used in actual equipment. For example, the complete biasing network may not be shown. This is done so you can concentrate on the concepts being presented without being overwhelmed by an abundance of circuit elements. With this idea in mind, the information that is presented in this chapter is real, practical information about video and rf amplifiers. It is the sort of information that you will use in working with these circuits. Engineering information (such as design specifications) will not be presented because it is not needed to understand the concepts that a technician needs to perform the job of circuit analysis and repair. Before you are given the specific information on video and rf amplifiers, you may be wondering how these circuits are used. Video amplifiers are used to amplify signals that represent video information. (That’s where the term "video" comes from.) Video is the "picture" portion of a television signal. The "sound" portion is audio.