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Thoughts on making choke cores.



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From:  Bob Schumann [SMTP:tesla-at-america-dot-com]
Sent:  Sunday, March 22, 1998 7:55 AM
To:  tesla-at-pupman-dot-com
Cc:  USA-TESLA-at-list.iex-dot-net; Tesla-2-at-emachine-dot-com
Subject:  Thoughts on making choke cores.

Howdy coilers,
	As many other coilers have here, I had bought some of the iron-powdered core
toroids from Hosfelt to make RF chokes from. I followed the directions from
some
previous builders and wound the core with layers of electrical tape,etc..
and have had
no problems at all , in fact I liked then but then Hosfelt ran out and so
did I.

I have been trying to come up with a better, simpler and cheaper way to
have some
good beefy chokes and this is my newest thought:

The toroid part would be one of those plastic 'doughnuts' that you see in
the toy
store for small infants. We have all seen them, they are about 4 to 5
inches in
diameter and some have bigger inside 'doughnut holes' than others. 
Some sort of opening would have to be made in the toroid for it to be filled.
What to fill it with? This is something I am thinking on as well. You can
go to
any automotive shop that 'turns' brake rotors and find a goldmine of fine iron
shavings that have come off the brake rotors. Using a sieve, you can
collect the
smallest particles. I am still trying to decide what makes a good compound
to mix
with these iron shavings and the best I have come up with is plaster of
paris. Mixing
the plaster with the shavings  will yeild a compound to fill the plastic
doughnut with.
Experimenting with iron shaving - plaster ratios, one should be able to
come up with
a good ratio that would be just fine. I don't know how much iron shavings
is too
much and may cause core saturation but that would be in the experimentation
process. I had also thought of using an extremely thick oil such as automotive
gear oil as the compund mix but I envision that the iron shavings might
'settle'
which would not be acceptable. Any ideas are welcome. Neccessity is the mother
of invention.

Bob Schumann