I have spent a fair amount of time trying to find an answer to this question. It is regarding the relationship between the diameter of wire, and the inductance of a coil. I know it is a design consideration in the calculation of the inductance of some types of coils and transformers; and I know how to compute the value of L, the Q, and the other parameters of an air wound coil. There are also formulas (formulae) for calculating the inductance of a coil wound on a coil form with an adjustable slug iron core; as long as the permeability is known. All that stuff was basic theory needed to pass 1st phone, Advanced, 8th grade science, etc.
Here is my quandary. Say I have a multi aperture toroidal core. The type used as a wide band RF output or driver transformer, for example. Lets make the core a two holer of say, type 43 material, with three turns of silver coated Teflon wire.
The core chemistry will remain the same, the turns count will remain at three, the test frequency will remain at 20 MHz, and no parameter will change, except for the wire size.
What effect would changing from say a 16 AWG silver plated Teflon wire to an 18 AWG wire, of the same type and style, make on the inductance at the test frequency? It is my contention, that the change in inductance would be negligible. I'm sure it would change slightly, but not enough to greatly change the output level at the test frequency.
I figure, that due to the characteristics of a toroidal core, and the way it affects inductance, which is why they work so well in wide band circuits, that about the only thing that would make a radical change in said inductance or output of the transformer, would be the number of turns. The main consideration for wire size here would be the amount of current that must be safely passed.
About the only thing I can locate, is data on the actual ID, OD, and composition of the multi aperture transformer form itself, and the maximum number of turns one can make with a given size wire, for the given ID. Obviously, if the toroid form was thicker, thinner, of have more or less iron in it, a change of inductance would be expected, just as would more or less turns. But how about changing the wire diameter from 1.0 mm to 1.3 mm?
It appears that in a straight air wound coil, or even one wound straight on a variable slug coil form, the diameter of the wire would have a greater impact on the overall inductance then that of the toroid.
Of course, I could be full of shit, too.