Ken Scharf wrote:

Anybody have an idea how to determine what material a surplus toroid
core might be made out of? I tried winding a known number of turns on
one and then measured the inductance on a Q meter, but how would that
relate to the the permability factor?

Probably the easiest way is to compare your inductance to tables of
inductance for various core types in your size.
http://tritium.fis.unb.br/Fis3Exp/fc...nd/toroid.html

Or you can go back to the basic physics and solve the formula for
permeability.
http://hyperphysics.phy-astr.gsu.edu...ic/indtor.html

--
John Popelish