LRDG Wireless set up

[Bruce MacMillan]

In the photo from Charlie it shows a 4pdt switch on the side of the vehicle. It's in a convenient place on the side where batteries would be kept. My thoughts are this is for charging batteries. Here are some diagrams of the battery system from my M152 sigs van. You can see there is a 4pdt switch to select battery banks and each bank has a pair of wires connecting to the switch. This allows one set to be used and the other to be charged. The knife switch is not rated for radio frequencies so you wouldn't want to attenuate the already low power output.

[Bruce Parker (RIP)]

My 2 cents. Almost every British radio truck and even carriers used a 12 volt electrical system for the wireless completely independent of the 6 volt vehicle system. The 12 volt wireless system included either replacement batteries delivered every morning (along with your rations I presume) or two sets of batteries so one could charge while the other was operating the radio. This arrangement would be modified for setups working away from 'base' as the LRDG did, so a self contained system with a generator is the most likely. Jumper cables to pairs of 6 volt wireless batteries to charge then put in series for 12 volts?? That would be about the only way using the truck generator if a chorehorse wasn't available.

As to the type of radio, it seems 11 sets were first used, but did they ever change over to 19 sets? The electrical system above would have accommodated either.

[Mike Cecil]

Hi Bruce,

Interesting comments, so I'll chuck this into the mix as well: the Australian Cruiser Tank used three different voltages (6V, 12V and 40V), with the 6 & 12 volt systems reliant on the same design/amp-hour 6 V batteries as the 6V system. The 6V system was grounded to the hull.

The 12V system used 2 x 6V batteries and was wired independently and 'sealed' from the vehicle. A 12V generator was included, run by a connection to one of the transfer case lay shafts.

My point here is that the same 6V battery type was used for both, so could be changed over in the field (with some considerable difficulty) between systems if needed. While a single 12V battery would have reduced the stowage problems a little, battery commonality made interchange between systems possible and also simplified the supply stream.

Mike

[Bruce MacMillan]

Originally Posted by Bruce Parker

As to the type of radio, it seems 11 sets were first used, but did they ever change over to 19 sets?

Good question, I know there were issues with the 19 set in North Africa due to the heat. I just watched Sea of Sand on youtube and wonder if the trucks used were ex LRDG? Here's a clip showing a WS19 but as the movie was filmed in 1958 it may not be period correct for WW2

[Charlie Down]

Gentlemen, thank you for your input, that has given me much to ponder.
To quickly answer some questions
WS11 was used throughout the campaign, it worked they could mend it and it met their needs..
Supply dumps were established throughout the desert. Petrol, water, food and medical supplies seem to be the main items. No mention of batteries, let alone different types/spec.
Batteries. The truck battery and the wireless battery on the driver sidestep are the one known about. Whether the wireless battery was 12 volts? I'll see what I can find about any other batteries, but currently looks like too few batteries for the job. I need to look into this.
Chore horses are mentioned but the inventory (late 1942) suggests there were only enough for HQ. However at other times the situation could be different.
The photo suggests to me that there was one large knife switch and 3 other smaller (knife?) switches, as opposed to 4 ganged together. however I understand the concept of the ganged 4 switches, just trying to work out how that idea could be accommodated by the truck 's wireless set up.
I presume the trucks were supressed for wireless use, maybe all the trucks at the factory, but there is no mention of it.
The trucks in the film 'Sea of Sand' were mostly Dodge trucks, but there was at least one (ex RAF?) Chevrolet 1543 long wheel based truck modified to look like a 1533X2.

I think I need a lie down for a few days to take on board all the information and then cross reference it to any documents!

Attached is the best view of the wireless battery on the sidestep. I don't know if that helps in any way. 12 Volt maybe?

[Mike Cecil]

Charlie,

As far as I'm aware, only the top view of the battery will tell you the voltage (by the number of cells visible).

Mike

[Charlie Down]

Ok. Found these LRDG Documents, I think originally marked 'TOP SECRET'.
So they used 2 standard 6 volt truck batteries, one from the truck and one mounted next to it on the side step. They were used in series for wireless operation and in parallel for charging, via a 'special series Parallel switch'. The trucks generator charged the batteries and if on road watch for several days batteries were swapped with batteries from another truck. This required no chore horse charging set.
The second document shows the maintenance procedure for the wireless equipment in the field.
So does that mean the panel only needed one knife switch, and they used a standard 4 switch panel and removed the other 3 knife switches, or a 2 knife switch panel with a knife switch removed? The 2 positions of the switch would be series and parallel.
Looking at the attached compilation of switch panels I think I'm leaning towards a 2 switch panel with one switch removed.
Also what is involved with setting a truck up to be wireless suppressed?
Could the photo at the start be another truck waiting to swap batteries, based on this new information?

[Lynn Eades]

There is quite a lot involved in radio suppression on a veh. Lots of earth / bond straps every where. A suppressor on the generator and the distributor, some shielded wiring (generator to regulator) etc. and filter boxes. Have a look at Jeeps, and Dodges. The American manuals give pretty good info on this sort of thing, with lots of photos. Most American production rolled out of the factories with it all done from around 1941. The thing is that its not just the veh. with the radio in it, It's all of the vehicles in proximity that cause a problem.