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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.
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.
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.
9:1 VOLTAGE UNUN. Version 3. 1:9 voltage unun using a FT140-43 Ferrite Toroid Core for 1.0MHz to 60MHz.
The toroid is a T130-2 Iron Powder core, with 3 x 9 turns of 18SWG enammeled copper wire, and the connections can be seen below. The triple winding connections. 8 turns is shown here, but more turns is preferred. 10 would be ideal.
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. Parts list.
