[Bruce Parker (RIP)]

An alternative power supply to the Battle Battery was the Vibrator Power Unit or VPU. It is 22 ½ lbs, 14” tall by 10-1/2” wide by 4” deep. The outer case is aluminum with web straps allowing it to be carried on a signaller’s back or attached to his web equipment, but was also intended as a ground or vehicle power supply. Inside the case was another metal case secured by a metal strip with pins at the top and rubber nipple shock mounts on the sides and bottom. The inner case, made in the U.S.A. by Electronic Labs Inc., had a vibrator power unit on the top and a space in the bottom for two lead acid batteries: ‘A’ and ‘B’. On one side were leads for two headsets and another to connect the VPU to the wireless set. On the other side was a small switchboard and plug to allow each of the batteries to either operate the set or charge from an external 6 volt battery. This inner unit is finickity to remove and replace in the outer case even when new and must have been prone to breakage and frustration in actual use. The outer case had a full set of spare valves in the lid and small plastic windows likewise labeled “A” and ‘B’ to check fluid levels and condition of the batteries. The switchboard and cables were accessed by small hinged doors on the sides of the outer case.

The advantage of the VPU is that it would operate the set indefinitely so long as there was a 6 volt truck battery around.