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W2FMI Transmission Line Transformers,
(Jerry Sevick's BALUNs & UNUNs)


CWS ByteMark's Baluns (Balanced to Unbalanced) and Ununs (unbalanced to unbalanced) transformers are developed jointly with Dr. Jerry Sevick, W2FMI, who is known worldwide for his work on transmission line transformers. These Baluns and Ununs are probably the most efficient high power impedance matching transformers available in the world. They have an efficiency of 98% to 99%, and will enable you to achieve high signal strength in your systems. CWS ByteMark offer the widest and most comprehensive selections of these Baluns and Ununs.

Background on BALUNS and UNUNS

Baluns and ununs (unbalanced-to-unbalanced transformers) belong to a class of matching devices known as transmission line transformers. They transmit the energy from input to output by a transmission line mode instead of by flux linkages as in the case of conventional transformers. When properly designed, they can have extremely high efficiencies and very broad bandwidths. The theory of operation of these devices rests chiefly on that of chokes and transmission lines. A balun or unun is simply a choke that isolates the input from the output (thus only allowing transmission currents to flow) and a configuration of transmission lines.

A major difficulty (even today) is that this very important and popular class of matching devices is not included in the curriculums at universities. In fact, there are no standards for the specification and testing of these devices by any professional group! As a result, practically everyone still perceives these devices as conventional transformers and not transmission line transformers. To remedy this, it has been suggested that this class of transformers be called broadband transmission line matching networks.

For more detailed information, please read the following written by Dr. Jerry Sevick:.

  1. Transmission Line Transformers, 4th. Ed. published by Noble. Contains analysis, characterization, and designs of BALUNs and UNUNs. Good for students, engineers and designers.
  2. Transmission Line Design Handbook, Contains 48 improved designs of BALUNs and UNUNs covering all impedance ratios. Good for do-it-yourself, hobbyists, and Amateurs.
  3. Undestanding Building and Using Baluns and Ununs: Practical Designs for the Experimenter, Published by CQ Communications, Inc. Jerry Sevick. The all new definitive source for his latest practical information and designs. Unique opportunity to learn about the application of baluns and ununs for dipoles, yagis, log periodics, beverages, antenna tuners, and countless other examples. This book is offered at

Please click the BALUN and UNUN for descriptions and prices.

Note: CWS Bytemark is another division of, Inc

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