On 8/20/2013 1:00 PM, Tom W8JI wrote:
By squeezing or spreading turns to change mutual coupling between turns, a T157-2 core can have almost 2:1 impedance shift! That tells us it has considerable flux leakage.
So-called "self-shielding" and it's inverse, leakage flux, also depend on permeability, which in turn depends on the material and the frequency of interest. Fair-Rite data sheets for their materials clearly show the variation of permeability with frequency.
And when we squeeze or spread turns we are also changing stray C of the winding.
73, Jim K9YC _________________ Topband Reflector
