Powered Iron makes low loss toroids but are not useful as EMI
suppressors. The inductance and the net impedance is low also. As we all
know, ferrite works very well if you get the right mix.
73
John
K5PRO
Message: 1
Date: Fri, 6 Dec 2024 07:16:22 -0800
From: Michael Tope<W4EF@dellroy.com>
To:amps@contesting.com
Subject: Re: [Amps] Alpha 77dx L5 help
Message-ID:<e7306fd4-bce1-4987-bf69-311b1afd25e1@dellroy.com>
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Hi Jim,
My only familiarity with iron powder is there common application in
high-Q RF inductors. They are available in a wide range of sizes
depending on the power level involved. I don't know if they have any
useful application for RFI suppression at frequencies above their
intended application range.
73, Mike W4EF................
On 12/5/2024 1:47 AM, Jim Brown wrote:
Thanks Mike.
I don't know much about those materials, but I've learned a LOT about
ferrites, which are quite different.? Ferrite cores exhibit
self-resonance, and within that frequency range, are quite useful for
suppression -- i.e., EMC. Many ferrite mixes that have useful
conventional inductive circuit properties (that is, as cores for
inductors) at low frequencies have self-resonances that are useful for
suppression at higher frequencies. And these resonances, which mostly
are in the VHF range for single turns (that is, one pass through the
core), can be moved down (as far as 160M) by winding multiple turns
through the core. That is the basis of my work on common mode chokes.
For a lot of reasons, Fair-Rite #31 is the only mix I've found that is
useful at HF. Another great researcher, who has chosen to remain
anonymous because he works in major labs where professional jealousies
can be? a problem, was a VERY important contributor to my work. I
continue to thank him for it.
73, Jim K9YC
On 12/4/2024 10:31 PM, Michael Tope wrote:
FWIW, the pertinent technical data for the Micrometals #2 Iron Powder
material mix (relative permeability, mu = 10) can be found here:
https://www.micrometals.com/products/materials/-2/
If you look at W6SAI's "Radio Handbook", a stack of two or three
T200-2 cores is specified as part of the PI-L networks in several of
the HF amplifiers described therein.
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