Jim and Peter:

I use PA0SE dog bone insulators, which are excellent for QRO using small
antennas. The insulators were fixed to supports using 2mm nylon cord.
Twice now the antenna has come down because of a failure in the nylon

cord.

At the point of the break there is no indication of any burning but the

ends

of the nylon cord, where the break occurred, are hard rather than frayed.

First Jim, I am a bit thick I am unable to visualize your wire loop concept.
When I used, 40+ years ago, high power on 3.7 MHz AM mobile, I had corona
problems that were  mitigated by welding a copper penny on the end of the
whip.  Are you suggesting to just hang a wire loop at the end of a point in
the wire to perform a similar disipation function?

Peter, my situation here is the same with a variation.  I use yellow
polypropelene (sic?) rope, it rots in the sun fairly fast but usually my
antennas change far more often than the rope fails hi, and I found not only
a "welded end" but I also found considerable stretching due to heat in the
last foot or so to the insulator.

One kind soul offered that the insulator fractured because of the effects of
small shot from a shotgun shell but the insulator failed in long shards (as
glass has been known to do) rather than the powder associated with the
effect of a projectile.

Larry
VA3LK