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4 cze 2021 · Easiest way to find out is to build it and measure empirically. Using triple windings allows closer wire spacing between the transformer input and output (primary and secondary) windings which can improve the magnetic coupling coefficient.
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.
12 sie 2016 · In that case, winding your unun on a T106-2 core—or even better a T157-2 core that has an A L of 14—will work OK. If you’re like me, though, and want a 9:1 unun to actually give you a 9:1 transformation over most of the HF bands, then use a ferrite core.
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.
This video discusses End Fed antennas and particularly End Fed Random Wire antennas for ham radio. Additionally, we go through the process of building a 9:1...
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. Parts list.
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.
