My guess on the knife switch, Charlie, is that it is the selector switch between two distinct aerial setups for the wireless set so the operator can change quickly from one operating frequency to another.
Another factor to consider. Vehicle starting batteries are a very different design from wireless batteries. They are meant to provide a huge starting current quickly and then have very little to do other than sit and get recharged.
Wireless batteries, on the other hand, are designed for deep discharge where a few amps are needed over as long a time as possible. In fact, you will often find operating ratio data provided in wireless manuals advising operators of the best possible combinations of receiver time (low amp draw) and transmitter time (high amp draw) to enable the wireless batteries to last on a full charge as long as possible. Wireless batteries are quite happy under a float charge, most vehicle batteries do not like it. Vehicle batteries will experience increased failure under high deep discharge conditions as well.
The LRDG would have been aware of all the limitations of the two sets of batteries on patrol. Just another set of supply considerations each time they set out.
One other thought. What is known of the fuel supplies for the LRDG? Did they have access to fuel depots placed in the desert while on patrols, or did they have to carry all they needed from start to return? If fuel was not an issue, having a chorehorse as part of your kit would make sense. If fuel was critical, maybe they deleted a chorehorse from patrols and used PTO driven generators for charging the wireless batteries. Either way, you would still need the switchboard seen tucked behind the drivers arm.
David
|