[Elecraft] toroid turn spacing-how it matters(?)

[Masleid, Michael A.]

Hi Rick,

Here's another way to look at it perhaps:

>The core captures all of the magnetic field from each
>wire turn regardless of the location of the wire with
>respect to the body of the toroid.

The H field doesn't notice that the toroid exists, it depends
on current, turns, and distances.

The B field depends on permeability times the H field.

The B field in the toroid core is boosted by the
relative permeability of the core material.

The total enclosed B field time turns (again) does the inductance.

Since the permeability of the core is so much higher than
the permeability of the air, the part due to the air is
usually not significant.

But, the cores used for HF work don't have very much permeability,
so the part in the air matters some, and the shape of the
winding changes the inductance by a noticeable amount.  It would be
very noticeable for plastic VHF cores.

73, de Michael, AB9GV