[Amps] Guidelines.....toroids for tank ckts

[Colin Lamb]

Toroids do not need to be wound on powdered iron or ferrite.  A core with no permeability works.  The advantage of such a core is the self-contained energy.  You can wind a core on teflon or some other material.  The disadvantage is that more wire is needed.  

A number of years ago, I made an antenna tuner for field day and wound the coil on a bagel.  It worked fine and got people's attention. Much easier to wind on week old bagels.   

That may have been the same year my final was a 5U4G.

73,  Colin  K7FM