Masters Theses


"The analysis of tuned grid-tuned plate Class C power amplifiers has been treated by many authors in many ways. The methods differ in accuracy and in time required to obtain the end results. A survey of most important of these methods was taken up by the author of this thesis with an aim towards studying their accuracies, advantages and disadvantages. A general survey of this type of analysis has not been found in the literature. In this survey only the most important phases of the tuned grid-tuned plate single ended Class C power amplifiers are discussed.

This survey has been divided into four main sections.

Part I. In this section a general survey of the following methods of solution of Class C amplifiers has been made.

(a) Exact Analysis. This is a graphical analysis based on the use of constant current curves. It was derived by I. E. Mouromtseff and H. N. Kosanowski in 1535. On the basis of this analysis, a method of obtaining contour diagrams of various quantities such as output power, plate dissipation etc., are also discussed.

Following the discussion of contour diagrams, an analysis by W. L. Everitt is given. This analysis is more or less exact. It makes the use of transfer characteristics of tubes and is based on the assumption that the transfer characteristics are linear.

(b) Approximate Analysis. Four approximate methods of solving Class C amplifier problems have been discussed in this part of the thesis. The first method is that of F. E. Terman. This analysis is based upon the total space current in the vacuum tubes, and has been applied to triode as well as the pentode tubes. At the end of this analysis an outline for the design of Class C amplifiers is given. This is followed by a discussion of an approximate analysis of W. G. Wagener. In the latter analysis, a simplified method is given for quickly computing with reasonable accuracy the performance of Class C amplifiers. The third analysis is that of E. H. Schulz which makes use of radio frequency charts. These charts consist of various quantities such as the ratios of various components of current etc., as a function of the operative angle of current flow. The fourth analysis covers a step by step procedure of Class C amplifier design. This analysis makes use of charts in which ratios of peak, plate current to d. c. plate current are given as a function of the ratios of fundamental plate current to d. c. plate current and also uses constant current curves.

(c) Illustrative Computations. In order to illustrate the various methods of analysis, an actual Class C amplifier design, problem has been worked out using a particular tube. The accuracies of the various analysts are compared and their advantages and disadvantages are discussed.

(d) Factors affecting operation of Class C amplifiers. Here, a brief discussion has been given about the requirements that should be fulfilled by the plate tank circuits. Also, an analysis of grid driving power is discussed and a brief resume is made of the methods of obtaining grid bias voltage in Class C amplifiers.

Part II. This section covers modulation of Class C amplifiers. In the first part of this section, a general discussion of amplitude modulation is given and this is followed by a discussion of a particular method of plate modulation. The remaining portion of tills section is devoted to analysis and methods of grid, suppressor, cathode and screen grid modulation.

Part III. Neutralization of interelectrode capacitance has an important bearing on the performance of Class C amplifiers, and is discussed in this section.

Part IV. In this section some of the problems that are involved in operation of Class C amplifiers at high frequencies are discussed. One of the most important of these is the effect of transit time in operation of tubes at high frequencies. Also, the effects of interelectrode capacitance and lead inductance are considered"--Introduction, pages 1-4.


Skitek, G. G. (Gabriel G.)


Electrical and Computer Engineering

Degree Name

M.S. in Electrical Engineering


Missouri School of Mines and Metallurgy

Publication Date



viii, 201 pages

Note about bibliography

Includes bibliographical references (pages 195-197).


© 1951 Chandrakant D. Gandhi, All rights reserved.

Document Type

Thesis - Open Access

File Type




Subject Headings

Power amplifiers -- Evaluation

Thesis Number

T 962

Print OCLC #


Electronic OCLC #