It seems all ferrite shapes are made from the fine powder.
I wanted some to put as a 'goop' on some coax to make
a choke balun. There are various grades - mine was 15000u.
(IIRC)

It is very fine indeed. There is some in the modern
toners for the cheap laser printers and copiers.
It replaces the 'developer' of yesteryear.
In fact I had a lot of the old toner and after some
experimenting came up with a brew of ferrite/toner
good enough to use in the copier here :-)

Try some toner with a magnet - it sticks if there
is ferrite in there.

Murray vk4aok


Ed Price wrote:

"Roy Lewallen" wrote in message
...

I stand corrected. I hadn't encountered ground down ferrite as you
describe. I should have realized it existed, though, since I've used
ferrite loaded paints and silicone rubber, which must contain ferrite
in this form. Thanks for the correction, and to the original poster I
apologize -- please disregard my posting.

Am I correct in assuming you'd end up with ferrites of lower
permeability (and higher saturation flux density) than the unpowdered
original, due the inevitable air gaps between particles?

A major manufacturer of ferrite-loaded materials such as paints and
silicone rubbers is Emerson & Cuming. They might be a possible source
of ferrite in powdered form.

Roy Lewallen, W7EL



I personally never saw ferrite any finer than a vaguely gritty powder,
and we had no need for anything finer in the technical ceramics that we
were making. But the ferrite paints are a good example that finer
grinding is common.

I think you are right about the smaller particles yielding high
saturation levels. And another possible source for ferrite in powdered
form might be Steward (in Tennessee).

Ed
wb6wsn