In article ,
John, N9JG wrote:

Yes, Amidon's price is fair, but if I can buy 10 of these large toroids for
$6 rather than $10, I would probably bite.

These toroids are for use as common-mode filters for wires leading to/from
electronic equipment. My ham rig operates primarily in the bands between 1.8
& 21.5 MHz.

You might want to check with electronic-surplus stores. Most of the
ones around here have a fair supply of ferrite cylinders and toroids
of various sizes (some pre-wound with wire, others bare). A lot of
them appear to have been intended for power-supply filtering
applications of one sort or another, and might be suitable for your
needs.

Being that they're ferrite, there's little or no standardization in
labelling or color coding (and many of them are "naked" ferrite with
no coding at all) - you'd have to buy a few, and then run some
inductance-vs.-frequency tests to see if you could figure out what
sort of ferrite mix was used and whether its inductance and loss in
your frequency range is acceptable.

It's a bit of a carp-shoot, but if you're lucky you might be able to
pick up a bunch of usable ones (if not necessarily of the exact same
size and mix you were thinking of) for rather less money... maybe as
little as a dollar or two each.

Hmmm. As an example, I just checked one surplus dealer (www.mpja.com)
and see that they have a Magnetics ferrite toroid, 1.9" OD, made by
Magnetics, of a type "J" ferrite mix (permeability 5000), intended for
EMI/RFI filtering (and for broadband transformers below 1 MHz). Data
sheet for this mix can be found at

http://www.mag-inc.com/pdf/Ferrites/...aterials_J.pdf

MPJA sells these for $3.95 each in onesies, $2.95 if you want 20 or
more. If those would do, you could buy 20 for the same $60 that you
were hoping to be able to spend for ten of the Fair-Rite toroids.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
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