On 10/26/2010 5:42 PM, Bill, W6WRT wrote:
> The Palomar data sheet says #6 is good for 2-30 MHz.
>
> http://www.palomar-engineers.com/Iron_Powder/iron_powder.html
>
> Where did your informaton come from? Perhaps different manufacturers use
> the same number for different mixes?
Mixes (and the numbers that describe them) are generally proprietary to
their manufacturer. Mixes #31, #43, #44, #61, #67, #73, #75, #77, and
#78 are all made by Fair-Rite Products, an excellent company based in
upstate NY. It was originally a family owned company -- he was the chem
engr and she was the EE. I met them at an IEEE EMC conference about six
years ago. They recently sold the company to a conglomerate. I don't
think they make any powdered iron cores.
FWIW, I would trust a reseller of ferrite parts to have a clue about the
USE of those products. For many years, all of them have sold a lot of
the WRONG parts for most ham applications, and always at VERY high
markups (typically 4-5X their cost).
The word "good" depends strongly on the APPLICATION of the part, which
in turn depends on the FREQUENCY. Virtually all cores have low losses at
low frequencies, but get lossy at high frequencies. "Low" and 'High"
varies a LOT from one mix to another. A core that is "good" for use in a
tuned circuit or a transformer at low to mid frequenciescan be AWFUL
for use in suppressing common mode current at low to mid frequencies.
And that same core would make a lousy inductor at VHF and UHF, but
excellent for suppression at VHF and UHF. Fair-Rite makes this quite
clear in their applications notes.
Again, I urge you to study my tutorial, previously cited. Much of this
tutorial material on ferrites has been incorporated in the ARRL
Handbook, beginning with the 2010 edition. I also urge you to study the
Fair-Rite Products catalog, which is a pdf on line. Start by studying
the materials pages near the front of the catalog that show graphs of
the inductive and resistive characteristics of the material vs frequency.
73, Jim Brown K9YC
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