There are a number of ways of making a ball gap. but more important is arriving at the correct spacing for the gap. The way rain is handled is usually by positioning the balls one above the other so a water bridge doesn't form between the balls.
Read this by Mark Persons: https://www.radioworld.com/tech-and-gear/understanding-arc-gaps-for-am-systems Here's another treatment: https://www.thebdr.net/articles/steel/twrs/LimitingStatic.pdf Kintronic sells them https://www.kintronic.com/shop/tower-ball-gap/ 73 Rob K5UJ _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector