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How to Make a Lightning Arrester for a Long Wire Antenna

Long wire antennas typically consist of a 100-foot length of copper wire connected between a tree and a shortwave radio. The risk of a long wire antenna is a nearby lightning strike will create a power surge sending a damaging amount of electrical current through the antenna to the radio. One way to protect a radio is to insert a lightning arrester between the antenna and the radio. A lightning arrester reroutes the surge and dissipates the electricity to a metal rod buried in the ground.

Things You'll Need

Nonresister type automotive spark plug
Aluminum bar 1/4 inch by 1 inch by 6 inches
Assortment of metal drill bits
Assortment of metal taps to create threaded holes
Electric drill
Two 6-32 size set screws

Instructions

- 1
  Drill a hole slightly smaller than the threaded section of a spark plug at one end of an aluminum bar.
- 2
  Tap a thread through the hole in the aluminum bar that matches the threads of the spark plug.
- 3
  Drill and tap a 6-32 size hole into the side of the aluminum bar perpendicular to and centered with the spark plug hole.
- 4
  Drill a hole at the other end of the aluminum bar the same size as the copper ground rod used to ground the antenna/radio system. Drill and tap a 6-32 size hole into the side of the aluminum bar perpendicular to and centered with the ground rod hole.
- 5
  Screw the spark plug into its hole in the aluminum bar and secure with a set screw. Insert the aluminum bar over the copper ground rod and secure the bar with a set screw. Connect a short lead wire from the antenna to the hot terminal end of the spark plug. Adjust the spark gap to a clearance of 0.015 to 0.020 inches. The lightning arrester is now ready to use.

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