[Bruce Parker (RIP)]

This week’s items qualify as the most boring so far, yet they are a vital part of both line and wireless communication systems. Grounding sets to eliminate static interference or grounding line equipment to maximize its performance was necessary and a precaution every good signaller became proficient in.

The small spike, shown here in its fitting on a ’37 Pattern web brace was used to ground field phones, Fullerphones and remote control units. The web brace was most often the carrying strap for the unit. While it could be used to ground the unit for its own sake, generally this spike was used as a ground when signalling over one wire. You may recall in previous weeks that line equipment could be used with two wires connecting the sets, or a single one with the second wire going to ‘earth’. The spike shown is used for this purpose. It is made of steel and is 13” long weighing 1-1/2 lbs. The captive knurled nut is for the wire connection and the L-shaped handle at the top is for depressing the spike into the ground by hand. This Canadian example was made by MCA (I’m not sure who that is) in 1942.

The large spike is used for grounding wireless trucks and vans against static buildup or interference from the vehicle’s electrical system, however wireless trucks also employed suppression systems for their ignitions and were well bonded with woven metal ground straps between frame, engine and body components. The spike is 36” long made out of 1-5/16” diameter bronze tube weighing 6-3/4 lbs. It has a reinforced point and head for pounding into the ground. The black band indicated the depth to which the spike was to be set. A rubber coated wire was used to attach the top of the spike to a grounding point on the vehicle. Often when there was no ability to sink the spike because of rock, or for operating when stopped for short durations, the spike was grounded by placing it wedged under the vehicle’s tire as shown. This spike is again is a Canadian MCA made example dated 1942.

The last photo is of the factory applied “W/T” stencil painted on vehicles to indicate they were equipped to take a wireless set. This typically meant not only provision for the wireless set carrier and aerial brackets but also that it had ignition suppression and grounding against radio interference. It is 4-3/4” wide with 2” tall white letters.