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12 sie 2016 · It’s relatively easy to build a 9:1 balun. One of the most common designs is to wind nine turns of a trifilar winding around a toroid core. Trifilar means that there are three wires wound simultaneously around the core.
4 cze 2021 · Using triple windings allows closer wire spacing between the transformer input and output (primary and secondary) windings which can improve the magnetic coupling coefficient. This can slightly improve power transfer efficiency, as more power goes into the output/antenna windings instead of heating the toroid.
The heart of the Un-un uses a Type 43 [FT240-43] core and consists of a trifilar [3 wire] winding arrangement around the core. The wires are wound to create a 9:1 transformer and would ideally suit an end-fed long wire antenna fed against ideally – a good counterpoise, or a good radial system.
Figure 2 Schematic of the 9:1 voltage unun. Typically unbalanced = 50/75 ohms too unbalanced = 450/675 ohms. Figure 3 Wiring of the 9:1 voltage unun. Note this drawing shows winding connections and not the number of turns required. See article for details.
These are sometimes known as a Magnetic Longwire Balun. Its really an impedance transformer (9:1) to feed a high impedance, end fed (unbalanced) random wire which is likely to be a few hundred ohms, and transform it into something closer to a 50Ω (unbalanced) coaxial input, hence UnUn.
17 cze 2009 · To understand how to construct an unun lets build a 9:1 version. You will need a T-200 (red) toroid and three pieces of wire, each 24 inches (60cm) long . It will also help if you a small plastic box with an SO239 socket mounted at one end and with two wing nuts or mounting posts at the other.
Step 3: Wind the 9:1 unun toroidal transformer. NOTE: For the 20w kit, nest the smaller toroid in the center of the larger toroid and treat them as if they are one toroid for the following steps. Uncoil the magnet wire. Start with the end of the wire in the center of the toroid and begin winding as shown in the image to the right.
