Coil Forms - Crystal Radio

thingiverse

I designed two specialized coil forms for my crystal radios, dubbed Basket Form V4 and Spider Form v2. These innovative designs enable you to directly wind coils onto them. I've experimented with a range of wire gauges, from 20 AWG magnet wire to as fine as 30 AWG, with 22 AWG proving the ideal balance. When working with the basket coil form, be mindful not to overtighten the wire, as excessive tension can cause the form to warp over time. In contrast, the spider coil wrap allows for a snug fit. I also employed a separate mounting system called Basket Coil Mount when building standalone baskets. To optimize my coils' inductance, I consulted various calculators and discovered that regardless of the construction method, my coils consistently measured higher than expected, necessitating wire trimming to reach the desired value – likely an innocent calculation mistake on my part.