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11

Baluns are a source of much confusion in the hobby, and are probably one of the most common causes of RFI, common mode noise reception, and poor antenna performance. Folks try to shoe-horn a lot of very complex values and characteristics in to a very linear way of thinking, and most of it is just flat wrong. Starting from the top: That design should in ...


6

I'll explain the operation of that balun very briefly: for the differential mode (which by definition has equal but opposite currents on each conductor), each conductor induces an equal but opposite magnetic flux in the core. These magnetic fluxes cancel, and so the differential mode sees no inductance: it's as if the core and the windings aren't there. ...


4

Short answer: No, and in fact you'll often get more bang for your buck by avoiding coaxial baluns. The description of the balun's purpose in an antenna system you quote is an oft repeated bit of "common wisdom" in ham radio, but it is such an over-simplification that it is at best drastically misleading and at worst, just plain wrong. The purpose of a ...


4

This is a magnetic flux transformer, not a transmission line transformer. It works by flux coupling just like a mains power transformer. So the bifilar part isn't too special, nothing like a transmission line transformer. In a regular flux transformer, the position of the winding doesn't really matter, only the number of turns. At RF though there is the ...


3

VHF transmission line baluns are very difficult to construct due to interwinding capacitance. As a result, the balun will have an undesirable self resonant point and will not typically reach the desired transformation ratio. Note that a balun does not consist of simple primary and secondary turns but rather primary and secondary transmission lines (2 ...


2

It more or less doesn't matter because it's so small, relative to wavelength. As such, a lumped element model is valid. You can make a conjecture to that effect by looking inside your antenna tuner (or really, a lot of HF equipment). Unless it's a fancy kind, there will be wires running whatever way between the components, with no attention paid to the ...


1

My biggest mistake was keeping my search on everything about ferrite and balun online, and receiving various piece of confusing information of mixed quality. Meawhile, I didn't even take a look at the most basic and authoritative reference material: The ARRL Handbook for Radio Communication. Today, I just obtained a copy of the 2014 edition, and immediately ...


1

The wire spacing can matter in a common-mode choke balun. A bifilar choke wound around a toroid forms a short transmission line whose impedance may be different from that of the line into which it is inserted. Thus, a bifilar choke can introduces some mismatch. (A tightly spaced enameled #14 bifilar winding is very ...


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