Review Questions

2. Why is gas used in low-pressure tubes? In high-pressure tubes?

3. Explain the operation of the grid-controlled gas triode.

4. What is the first alternating component in a half-wave rectifier? In a full-wave rectifier? What is the relation of the answers to filtering?

5. What is cutout in rectifier filters? Can it be prevented? How does it affect regulation?

6. Why are tetrodes and pentodes superior voltage amplifiers?

7. Distinguish between voltage amplification and power amplification.

8. Discuss the phase relations in a vacuum tube and its associated amplifying circuit.

9. What determines the low-frequency response of a resistance-coupled amplifier? The high-frequency response?

10. Explain how the decoupling resistors and capacitors of Fig. 19 function.

11. Discuss the application of Thévenin's theorem and Norton's theorem to amplifiers.

12. What are the proper approximate relations of r_p and R_L in triode voltage amplifiers, triode power amplifiers, pentode voltage amplifiers, and pentode power amplifiers?

13. Define class A, class B, and class C operation. What do the suffixes 1 and 2 mean?

14. Define plate-circuit efficiency. What is a typical value for a class A amplifier? For a class C amplifier?

15. What steps are followed in the design of a push-pull class A audio amplifier?

16. Repeat the preceding question for a class C radio amplifier.

17. Explain how frequency multipliers operate.

18. What is the basic principle of neutralization?

19. Describe voltage feedback and current feedback. What is a cathode follower?

20. Describe the so-called distributed amplifier.

21. Explain how a crystal-controlled oscillator operates. Repeat for a transmission-line oscillator.

22. Briefly describe cavity oscillators and enumerate several types.

23. Explain the principle of operation of a positive-grid oscillator. Name a practical application.

24. Explain the principle of operation of a basic Klystron, and of the reflex Klystron.

25. Discuss the traveling-wave tube. What is its outstanding characteristic?

26. Briefly explain how the magnetron operates.

27. What are varistors? Name several types. Give a few applications.

28. Repeat the preceding questions for thermistors.

29. What is a Transistor?

30. Discuss the role the Transistor may have in future telephone systems.