Warren K2ORS/WD2XGJ wrote:
During the period when I was transmitting using high power (1kW) with a
suburban antenna I noticed that once in a while it fell down - the
insulated line between the insulator and the support just 'broke'.
It turned out that the problem was caused by leakage across the
insulator when it became dirty or there was a build up of salt (I am
about 400m from the sea). This occured even though I was using PA0SE
supplied ceramic insulators about 120mm (5in) long. The problem was
fixed by using copper wire between the insulator and the support. I had
a ritual of insulator cleaning, and inspecting the insulators in the
dark with the transmitter switched on looking for blue tracking.
The problem only seemed to occur if the insulated cord support was
relatively short, say less than 2m long.
Prolonged tracking across an insulator will etch a track in the ceramic
glaze of the insulator and render is useless.
I take it this is a transmitting antenna? If so, then it will depend on how much power you are running and what kind of insulators you are using so you don't arc over from the top wire to the grounded tower. It will help if you use non conductive rope (dacron) between the tower and the insulator. I imagine that your biggest problems would occur if you ran high power and the insulators were wet. It would be a good idea to use the ceramic dogbone or other insulator with a long leakage path.