Take a look at the 8th line here:
http://www.karinya.net/g3txq/chokes/
10 FB-31-1020 beads slipped over RG213 produces a choke which is
resitive from 4MHz to beyond 28MHz. However, I would agree that using
beads is not an efficient use of the ferrite material - it produces
relatively low CM impedance for the volume of ferrite used. As we know,
you can wind much more effective chokes with multi-turns on toroid forms.
Steve G3TXQ
Jim Brown K9YC wrote:
> The only beads I know of that are suitable for HF are the tiny beads that
> W2DU found 30 years ago for his chokes. They only fit miniature coax, and
> it takes HUNDREDS of them to make a choke that still doesn't work as well
> as the multi-turn I've described. Those made with fewer beads are less
> effective AND they can be blown up with high power.
>
> 73, Jim Brown K9YC
>
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