Where in the U.S. can i purchase powdered ferrite in
order to make very large ferrite rod antennas?

Look up Steward in Chattanooga.
$10/# last time I bought. (10 years ago! :-) )

Cheers
Murray vk4aok


Radio Man wrote:
Where in the U.S. can i purchase powdered ferrite in
order to make very large ferrite rod antennas?

There's no such thing as "powdered ferrite". Ferrites are ceramics, made
by firing special clays at high temperatures with proprietary processes.
The process is similar in many ways to firing pottery, and making a
ferrite rod from "powdered ferrite" would be as hopeless as making a
ceramic vase from ground-up coffe mugs.

Roy Lewallen, W7EL

Radio Man wrote:
Where in the U.S. can i purchase powdered ferrite in
order to make very large ferrite rod antennas?

"Roy Lewallen" wrote in message
...
There's no such thing as "powdered ferrite". Ferrites are ceramics, made
by firing special clays at high temperatures with proprietary processes.
The process is similar in many ways to firing pottery, and making a
ferrite rod from "powdered ferrite" would be as hopeless as making a
ceramic vase from ground-up coffe mugs.

Roy Lewallen, W7EL


After the sintering step, the resultant granules are ground down to a
reasonably uniform size. These powders (and I wouldn't know what else to
call them) can then be compressed into pellets, extruded into rods, mixed
with a vehicle and cast as thin films, or sprayed onto substrates. You can
even blend them into a binding carrier (like wax or epoxy) and create
physical shapes (like rods or blocks).

The density of the ferrite particles can be controlled, yielding
inter-particle gaps as desired.

Ferrite exists in it's granular (powdered) form. However, since there's
likely little market for this stage, you might have trouble buying a few
pounds of it.

Ed
wb6wsn

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

Ed Price wrote:


"Roy Lewallen" wrote in message
...

There's no such thing as "powdered ferrite". Ferrites are ceramics,
made by firing special clays at high temperatures with proprietary
processes. The process is similar in many ways to firing pottery, and
making a ferrite rod from "powdered ferrite" would be as hopeless as
making a ceramic vase from ground-up coffe mugs.

Roy Lewallen, W7EL



After the sintering step, the resultant granules are ground down to a
reasonably uniform size. These powders (and I wouldn't know what else to
call them) can then be compressed into pellets, extruded into rods,
mixed with a vehicle and cast as thin films, or sprayed onto substrates.
You can even blend them into a binding carrier (like wax or epoxy) and
create physical shapes (like rods or blocks).

The density of the ferrite particles can be controlled, yielding
inter-particle gaps as desired.

Ferrite exists in it's granular (powdered) form. However, since there's
likely little market for this stage, you might have trouble buying a few
pounds of it.

Ed
wb6wsn

"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

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