This publication pertains to wide-band transformers, transmitting power of more than 100 watts.* Guides to application and test procedures are included. Appendices contain certain precautions and recommended practices. Provision is made for including data for use in the design of feedback amplifiers and control networks or otherre circuits in which knowledge of the transformer amplitude- and phase-frequency response is needed by the system designer. These transformers are required to transform voltage within specified tolerances of amplitude and phase when operating between specified impedances.