LRDG Wireless set up

[Charlie Down]

The wireless trucks carried a spare battery on the cab side step, so if they needed 12 volts then that would have been the obvious method of achieving it. Maybe for a long range signal they boosted the power to 18volts using another truck battery? Seems possible, but if so why not 24 volts? I just don't have that sort of knowledge. I know the Chevrolet 1533X2 Wireless trucks had a charging switch panel behind the drivers seat to manage the batteries (custom made most likely in Cairo, but I only have a vague idea of what it looks like after 5 years of looking for photos of it, see attached), so that took care of the 12v supply and charging them.