Figure 1 Schematic of the 4:1 Ruthroff voltage balun. Typically unbalanced = 50/75 ohms and balanced = 200/300 ohms. Figure 2 Wiring of the 4:1 Ruthroff voltage balun. Note this drawing shows winding connections and not the number of turns required. See table
Refer to the schematic (or figure 2-1A on page 18 of Jerry Sevick's book "Building and Using Baluns and Ununs"). Label the 7-8 lead as RED (colors correspond to the approximate colors of the wires used in
Refer to the schematic (or figure 2-1A on page 18 of Jerry Sevick’s book “Building and Using Baluns and Ununs”). Label the 7-8 lead as RED (colors correspond to the approximate colors of the wires used in
The easiest way to start building a 4:1 current balun is to order the AB240-250 K Mix Balun Kit from Amidon Associates. This kit includes the proper toroidal core, 12.5 feet of #14 magnet wire, 12.5 feet of Teflon tubing, and the Transmission Line Transformer Handbook 2 …
Build a High Power 4:1 Guanella Current Balun RF Choke and Transformer Using 2 Cores. As with the 1:1 Balun, there’s plenty of online info on building 4:1 Baluns. I’ve seen and read many articles on baluns and there’s’ plenty of pretty variable advice out there.
This time, we’ll show you how to make a 4:1 current balun, which will not only match a 200-ohm antenna system with a 50-ohm source, but minimize common-mode current, which can waste a lot of energy and introduce shack RF.
Perhaps the most common 4:1 balun is the voltage type, shown schematically in Fig. 3. The unit consists of two series windings, with a ground (common to the input connector ground) at the junction. The dots in the photo indicate the start of a bifilar winding, a parallel run of two wires around the core.
This project builds a 4:1 and a choke balun suitable for high frequency (1.8 – 30MHz) use. With modest common mode currents these baluns are suitable for 1 kw. The boxes are weatherized for outdoor use. Pictures are also shown of smaller 100 watt balun using similar construction with a small balun core. Materials: 2.4 inch diameter cores
An Improved 4:1 Current Balun Using a Single Core The shortcomings of the Guanella and Ruthroff 4:1 baluns gave rise to speculation of the possibilities of devising a 4:1 current balun comprised of a pair of 1:1 current baluns on the same core that can be used with float-ing, symmetrical, or even asymmetrical loads.
The notes in the following series of preliminary measurement reports make a start toward characterizing different types of balun designs with respect to impedance transformation. Part 1: Essential Background. Part 2: The Dual-Ferrite-Bead HF Balun: Some Preliminary Measurements. Part 3: Voltage Baluns: Some Preliminary Measurements