On Fri, 22 Oct 2004 11:48:35 -0500, Ford Peterson wrote:
>The fact that I do not understand surge impedances on random lines, the
>vagaries of
>various ferrite mixes, and the subtle nuances of EMI/RFI does not make me an
>idiot.
>Ignorant maybe, but not an idiot.
I certainly did not belittle you nor anyone else. I did suggest (indirectly)
that you were
being lazy, expecting others to do your work for you. I did give you a bunch of
specific
suggestions about how to chase your problem. I DID urge you to study specific
reading
materials and technical data that will help you understand things that you need
to know
to solve your problem. Those who know me (and those who have read this and
several
other lists for a while) know that I have spend thousands of hours teaching and
sharing
what I know. I have spent thousands of hours learning it, and I continue to
study. But like
Tom, I am unwilling to spend days on YOUR engineering problem. I have plenty
of my
own to work on.
You need to understand how ferrite materials work to solve interference
problems. The
Fair-Rite catalog does a very good job of explaining that. That's why you need
to study
it. The executive summary is that it turns the cable it is applied to into a
series R and L,
both of which vary with frequency. That R and L can help reject interference it
they can
be made to form a voltage divider with some "load" impedance. That load
impedance
may already exist in the circuit, or you may need to add it (usually in the
form of a
capacitor to ground). All of this is stuff that is VERY well covered in the
ARRL
Handbook, and which you have to know to pass the ham exams. The Fair-Rite
catalog
will give you the values of R and L for various parts that they make. The email
I posted
several days ago gave you a lot of specific information about how to increase
the series
R and L from a ferrite.
Another point. If you are a ham, you need to understand surge impedance of
lines. It is
VERY well covered in the ARRL Handbook and the ARRL Antenna book. Surge
impedance is simply another name for characteristic impedance.
Jim Brown K9YC
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