Book 3 — Lightning Switch for Wireless Aerials

Amateur wireless operators often cannot afford to buy a lightning switch such as is required to ground the aerial when not in use. The sketch shows such a device, which was made of a marble slab fitted with copper strips cut from discarded half-tone plates. The base was smoothed and polished to the size indicated, 4 in. wide and 9 in. long. The upper edges were beveled off, and holes were drilled near the ends through which bolts were passed to fasten the small brackets supporting the crossbar.

Discarded Copper Half-Tone Plates and a Piece of Marble were Used in Making This Lightning Switch for the Wireless Aerials

The copper pieces were made as follows: The plates of ¹⁄₁₆-in. copper were cut into strips, 1¹⁄₄ in. wide. Two were made 8 in. long; four, 3 in. long, and four, ⁷⁄₈ in. long. The 8-in. strips were fastened together with small bolts and a hole was drilled through one end of the joined pieces to fit the bolt which forms the pivot for the switch. The 3-in. strips were bent to form a ³⁄₄-in. angle, through which holes were bored for fastening to the base. The ⁷⁄₈-in. strips were clamped between the brackets at their lower ends to provide a slot for the crossbar. The bolts, by which the brackets were clamped together, were provided with binding nuts to which the wires were connected. A handle might be fixed to the crossbar, but this is not essential.