This final report, or transformer design manual, is divided into eight sections. Sections 1, 2 and 3 are the Abstract, Objectives and Definitions of Symbols respectively. Section 4 covers information of interest to the transformer user as well as the designer. This section includes a discussion on the transformer mechanical and electrical specifications, the test requirements, and the effect of the specifications on the transformer size, weight, and cost. Section 5 covers the audio frequency transformer design procedure. Here the design of an audio transformer has been broken into a step-by-step outline. Each step is briefly described, all necessary equations are listed and defined, and pertinent factual data is presented in tables and curves. Section 6 presents the procedural detail used to calculate the various parameters needed in the step-by-step design section. Section 7 includes the step-by-step design for the 350 kilowatt verification unit. The design summary for the 15 kilowatt and the 100 kilowatt units is also included. The test results for the three verification units are presented and discussed in this section. Section 8 is a complete bibliography of the literature researched during the contract period.