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LF: Insulator problems

To: [email protected]
Subject: LF: Insulator problems
From: "James Moritz" <[email protected]>
Date: Thu, 15 Feb 2001 14:57:59 +0000
Organization: University of Hertfordshire
Reply-to: [email protected]
Sender: <[email protected]>
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


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