Lightning Arrestor

Overview

A coax lightning arrestor sits in the feedline at the point where it enters the building. It normally passes the signal through untouched, but when the voltage across it rises above a threshold — from a nearby strike or static build-up — it conducts that energy to the earth connection instead.

Two technologies are common. A gas discharge tube fires at a few hundred volts and handles large surges, but it is slow and lets a brief spike through. A DC-blocked arrestor with a quarter-wave stub or a spark gap adds a second layer. Whatever the design, an arrestor is only as good as the earth it connects to.

Bands and modes

Band coverage

Modes

Safety note

Using it well

• Mount the arrestor at the building entry, not at the radio.
• Keep the earth lead from the arrestor as short and straight as possible.
• Bond the arrestor earth to the same system as the mains and station earth.
• Inspect the cartridge after any nearby strike and replace it if it has fired.