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RE- EMI Shield Beads




From: 	Robert Michaels[SMTP:robert.michaels-at-online.sme-dot-org]
Sent: 	Thursday, September 11, 1997 5:01 AM
To: 	tesla-at-pupman-dot-com
Subject: 	RE- EMI Shield Beads

        Ferrite beads can be very effective in rf absorption and are
        used routinely for such purposes.

        As said in the literature you found, they are effective only
        at high frequencies.   (Have you made any 25-MHz. Tesla coils
        lately, Gary?)

                                - - - - - - - -

        THHN is machine wire, not house wire.  I  =strongly=  recommend
        against using it in any sort of coil since its slick Nylon
        coating is very stiff, making it hard to wind and quite
        resistant to small-radius bending.

        If you are intent on using machine wire, I recommend MTW
        instead.  It is soft and flexible and decidedly cheaper
        than THHN.

                                        Regards,

                                        Robert Michaels,
                                        Detroit, USA


TL>From:  gweaver[SMTP:gweaver-at-earthlink-dot-net]
TL>Sent:  Wednesday, September 10, 1997 1:55 PM

TL>While looking threw an industrial electronic catalog at work today I noticed
TL>something called EMI shield beads.  It had a picture and a small amount of
TL>sales
TL>information about this things.  The informtion said.

TL>EMI shield beads.  These 6 hole ferrite beads wound with various
TL>configurations
TL>offer very high impedance in a small package.  Maximum suppression is obtain
TL>between 25 and 250 MHz.  1.5" x 30 mm.  100 pack $17.12, 25 or more packs
TL>$14.27
TL>per package.

TL>It does not say what value can be obtained.  I was thinking these might make
TL>good chokes for a TC wound with #14 THHN house wire.  Is anyone familiar wit
TL>these things?
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