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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