Insulator problems]

[Andre' Kesteloot]

James Moritz wrote:

> Dear LF group,
>
> I notice a few people have been having problems with insulators
> melting/cracking lately. I had problems with my insulators until I
> fitted some corona rings. What seems to happen when you try to
> put a lot of power into a small antenna is that corona discharges
> take place at the ends of the wire and at sharp bends where
> insulators are attached, where the radius of curvature of the
> conductor is small, and the potential gradient large. The heat
> generated either melts, cracks or sets fire to the insulators.
>
> So I have fitted the corona rings, which are just hoops of stiff wire
> about 100mm in diameter, to the "hot" ends of the 3 insulators (2
> plastic and 1 ceramic) on my antenna wire. This has eliminated any
> detectable discharges from the wire, even when operating at full
> power in heavy rain. The rings are electrically connected to the
> wire. The "cold" ends of the insulators are supported with non-
> conducting rope in my system, but with wire halyards you would
> want a corona ring on both ends of the insulator. It is a simple mod
> to make, and has made all the difference to my antenna, so might
> be worth a try if you are having problems.
>
> Cheers, Jim Moritz
> 73 de M0BMU