neonstrobe
- Joined May 15, 2009
- 190
I don't know what target inductance you needed, but I certainly would not use a bolt. One of the earlier posts mentioned that a bolt will give a poor result. In that case the effective RL will load the coil and give a low phase angle (instead of 90 degrees). So my advice would be to determine what inductance you need; decide if you could use air core, ferrite core or iron, then obtain a suitable core. If using a lot of turns the self-capacitance can be reduced by using old-fashioned layering (not the " free winding" of modern power transformers) and using fairly thick insulation sheets between layers. I've wound successful MW IF air cored coils that were so consistent that the three units resonated at the same frequency with the same capacitance values (presumably these were fairly well matched too) and although I fitted variables they were all set to the same value!