Tech Articles

Recently a few of the less open minded purists in our hobby have begun a negative compaign focused on the 4:1 single core balun (SCB) that we and about about 15 other balun producers offer.  It is important to note that we are only referring to those baluns built utilizing a single core or stacked cores wound with two separate windings.  In addition to these baluns, we also offer a classic two core wind in the model 4115 and a model 4116 Hybrid balun each with there own "best applicati …

How a 1:1 Guanella-Balun (Current-Balun) Operates By Jerry Sodus, KM3K In the spirit of the hobby, I pass along what I have learned and don’t profess to know all the answers. 1. The primary reason for this work is to explain how a particular Transmission-Line-Transformer (TLT) known as a 1:1 Guanella-balun operates. Three other commonly used names to describe this balun are: “current-balun”, “isolation-balun”, and “choke-balun”; I’d suggest committing all four names to memory. The 1:1 Guane …

Currently there is no industry standard for measurement of power ratings for baluns and ununs.  Because of the many different types of ferrites, build methods and levels of quality, comparison of the same type of balun/unun from different vendors can have very different outcomes when the unit is put in to service.  With this in mind, we have established our own standards based on the research and testing of Dr. Jerry Sevick PhD (W2FMI sk).  Dr Sevick is well known for his numerou …

Selecting the best toroid material or "mix" for baluns and ununs. Transmitting baluns Occasionally errors are made regarding core selection and this especially includes baluns, where some very strange ideas surface. One rather odd but somewhat popular idea is that adding a mixture of core types will allow both high power operation and high choking impedance in baluns by slowly reducing current through a balun. Other misleading claims are that extreme values of core ui (pronounced mu), such …

This is a partial reprint (with permission) of an excellent series of articles published by KV5R on shortwave antennas. His full series can be found at www.KV5R.com As previously stated, a ½ wave antenna radiates off of the sides, perpendicular to the wire. Longwire antennas radiate toward the far end of the wire. Let’s look at what happens to the directivity pattern of our 94-foot wire. As we dial up the frequency, the pattern of the antenna changes. The following diagrams show r …