PSN-L Email List Message

Subject: Re: Another mu-metal/permalloy question
From: meredith lamb mlamb1@..........
Date: Thu, 15 Jun 2000 10:32:27 -0700

Erich Kern wrote:

> Merideth,,
> If you do layers, it's very important they don't come into physical contact
> with each other. Some "bubble wrap" will do.
> Regards,
> Erich

Hi Erich and all,

Yes, I plan to insulate between any layers, and thanks for the
note in regard to it.  One or more web sites suggest a
insulating "spacer" of from 1/16 to 1/8", and, if using a ribbon
type material, that it shouldn't be spiral wound, which could
create a polarized effect of the shield itself.   Actually alot of
the "suggestions" per the web sites, and/or via this email are
not really financially viable for myself.  They are likely quite
true and effective for shield purposes, but out of range for
myself.  Commercial sources are available but rather
outrageous in their prices.

Actually this particular approach is kind of a surplus yard
route, but according to my brother Bob and his son, it
can work....but each individual project is a "cut and try"
gambit.  I really doubt that I'll ever find a adequate sized
container, ready made via any source, so the choice is really
not available, outside of this approach.  They have made 
many shields over a number of years using this kind of 
material, and combined they possess alot of electronics
experience (not so for myself...ha) 

Regardless though, it will be interesting to try it out and see
how effective it really is over time.  Perhaps in the most
positive aspect, (if it works as hoped for), it may offer a
means for others to try, who can't really afford the standard
route.  However, even if does, just the finding, identification
and use of this type material is probably also rather impossible
for probably 99% of the people interested.  The most common
source is older torroid coil forms, which contain ribbon wound
coils, which (hopefully) contain real permalloy.  Most are small
width, but the larger diameter/width ones are of course the
most desireable.  Another source could be "regular" rolls of
the item which are not contained within thin aluminum, but they
are even scarcer to find.  Arnold Engineering seems to be the
most prevalant brand (the coils are marked with a "ae.........
and other letters.  The last letter seems to designate its
effectiveness, with a "a" as standard, and a "f" as being the
best.  Other brands exist of course, but aren't known as to
their aspects.  The usual color of the AE torroid cores are
bright orange, but black has been noted in other brands.

We'll see........ha.

Take care,  Meredith Lamb


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Larry Cochrane <cochrane@..............>