These are two simple lightning arrestor designs. Antennas should always be disconnected from radios and grounded before lightning storms, and these devices are not substitutes for doing so. However, they will provide some measure of protection in case you forget to do so. And of course, nothing will provide total protection in case of a direct strike.
Design #1 consists of a simple air gap provided by two bolts that are filed down into points. The plastic box is water tight to prevent moisture from shorting out the air gap. Make sure the gap is around 1/4″ apart, as too wide a gap will not allow the spark to jump across, and if the bolts are touching the RF will be shorted to ground.
Design #2 consists of two SO-239 jacks mounted on a metal chassis, with a sharpened bolt providing the air gap to the center conductor. It is necessary to use a metal box to minimize signal loss. Make sure it is watertight.
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