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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 · 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.
Start with the end of the wire in the center of the toroid and begin winding as shown in the image to the right. Make about 7-10 full turns, evenly spaced around the toroid. The starting end of the wire will solder to the “GND” pad on the PCB.
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.
Figure 1 Typical 9:1 voltage unun and long wire antenna configuration. Construction . 1.25mm Enamelled copper wire was used in a triple bifilar winding of 4 turns wound evenly spaced around the L15 ferrite toroid core with the three individual windings wound close together.
14 kwi 2002 · My solution was simply to use some scotch tape every couple of inches to organize the cable. The scotch tape will disintegrate over time, but that's OK - the only purpose is to help you wind the wire around the core. Wind 9 turns around the core with the three wires.
