ferrite beads

Steve Lund stevel at hpsrfh.sr.hp.com
Fri Sep 10 14:52:02 EDT 1993

>What company has the ferrite balun kits that you slip the beads over the coax?
>Any luck with them?  Recommendations?  TNX Ralph Bellas, K9ZO

RadioKit, although I don't recommend using the kit they offer using the
Chosorb (?) beads.  The beads they offer for use on RG8 type coax do not
produce a high enough impedance to do a good job of choking any currents
flowing on the outside of the shield.  They work okay on 15/10m, but only
marginally on 20m and not at all on 40m and lower.  I made a number of
measurements on these beads and they don't seem to work in this application.

The original article on bead baluns was in March 1983 QST.  It used 50
#73 beads slipped over a teflon (RG142) cable.  I've been using this
method and it has worked wonders on my Mosley antennas (TA-53M).  I'm using
48 beads as they are sold by the dozen.  I believe that Amidon sells the
coax and, of course, the beads.  Don't substitute for the teflon cable--
the beads slip over it nicely and it can handle several KW at HF--something
that RG58 can't.

Steve WA8LLY/6

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