Had a similar experience with a 50 bead balun (choke) on a low dipole
where the beads were slipped over the coax and not protected from
flexing. I took off the plastic sleeve cover and found a lot of dust
and small fragments. Definitely not lightning or high transmit power
(max 200 wts) damage. Assuming two years of wind creating enough flex
to bang them against each other - ceramic is brittle - and as a few
beads break, then more room for the others to bang into each other...
However, this is speculation as I haven't taken apart the bead choke
using the same materials on my beam that is enclosed in a PVC tube and
can't flex to verify that's the root cause. Some day I'll replace it
with the better design from Jim, K9YC, and then get inquisitive.
73, George VE3YV / K8HI
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