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  #1  
Old 20-05-22, 12:25
Charlie Down Charlie Down is offline
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Default LRDG Wireless set up

I recently got sent a photo of a Y Patrol Wireless truck in connection with something unrelated (apologies the photo is from a private collection and I canít post it).
The photo showed a wireless operator sending/receiving a signal on his No11 set. What struck me was that the other truck (Chevrolet 1533X2) was parked so close to the wireless truck. It reminded me of another well-known photo of an identical arrangement (attached). The trucks only just allow the operator to fold down his work shelf and stand in front of it with his back to the other fender. The trucks are aligned so that the driverís seats are as close as possible to each other. Itís a very cramped set up considering they have hundreds of miles of empty desert to park in, and that they should be dispersed for camouflage, and so they present a minimal target should they be spotted by aircraft, as seen in most photos of a Patrol laying up for the night
So it strikes me that there had to be a reason for it. It is too deliberate and precise to be chance.
In front of the driverís seat on the floor panel is a battery inspection hatch. The arrangement reminds me of how you would place 2 vehicles to jump start one of them. So is this a Wireless power issue, or a wireless causing flat batteries and the other truck is on standby to jump start it? Would the use of the Wireless cause the battery to loose so much charge that it would need jump starting? If so what is the point of the spare battery on the side step of a wireless truck? Or is it for some completely different reason?
My knowledge of WW2 Radios is limited so hopefully someone with greater knowledge/experience can chip in.
Something else I noticed that I didn't expect is that the aerial is connected to the wireless only when the wireless is in operation and is plugged into the front of the wireless and out the front of the wireless compartment. I have always assumed the aerial and cables were 'properly' wired into the body, through various holes in panels and eventually the wireless. This set up means that the Patrol couldn't send/receive messages when on the move (ignoring the issue of connecting headphones into the wireless at the same time!).

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  #2  
Old 20-05-22, 16:07
Grant Bowker Grant Bowker is online now
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Feel free to tell me I'm wrong - I don't claim to be a wireless expert.
I have the impression that the WS19 required 12V (or 24V) to operate. Most trucks of that era were 6V. Is it possible that to avoid carrying both wireless batteries and charging sets (on trucks that were already heavily loaded) they devised a scheme to connect the batteries of two trucks in series to give 12V?
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Old 20-05-22, 18:14
Charlie Down Charlie Down is offline
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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.
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Charging panel.jpg   Tripod case.jpg  
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  #4  
Old 20-05-22, 19:58
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Ron Pier Ron Pier is offline
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Back then, 12 volts was often achieved with two 6V batteries wired in series. My knowledge is mainly to do with the 8cwt PU's. In these, the wireless was powered by two batteries whilst two more were being charged, either by built in generator or separate charger. The wireless was operated independently of the twin 6V vehicle batteries. Ron
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  #5  
Old 21-05-22, 11:35
Charlie Down Charlie Down is offline
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Hi Ron,
So the No11 set would use 12 volts from two 6 Volt batteries in series to power the set. On the LRDG trucks this would be achieved by using the truck 6 volt battery connected to the battery on the side step in series through the Charging Switch Panel.
Would there be any possibilty/need for a third battery to boost the signal for long range transmissions? And would sending the signal flatten the batteries sufficiently to require a alternative source of electricity to start the truck? Would the truck engine be switched off during signalling to prevent interference?
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  #6  
Old 21-05-22, 15:02
David Dunlop David Dunlop is offline
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Morning. Charlie.

Unfortunately, the idea of a third battery in the Wireless System to provide 18 volts to the wireless set will destroy said set. You would instantly burn out the heater/filaments in the sets valves which were designed with a very narrow +/- 12 volt operating range. The wireless set will have a theoretical operating range limit factored into its design that no amount of extra voltage will increase. A whole host of environmental factors may, however, increase/decrease range from time to time.

Wireless vehicles would definitely have had wireless suppression kits fitted to them to eliminate vehicle electrical interference with the wireless set. This was not necessarily done to other, none wireless fitted vehicles early in the war, but became much more common as the war progressed for several reasons, from both production considerations and bad experiences from vehicle operations in theatre. My thought would be that given the nature of the work the LRDG was doing, they would have wanted all vehicles wireless suppressed, either from the factory, or mods done upon receipt in the field. So the two vehicles being so close in your photo would not surprise me.

Keeping a pair of wireless batteries charged in the field by the LRDG would be an interesting challenge. The standard norm is a set of four 6 volt batteries. Two charged and running the wireless set while the second pair are being recharged through a charging system via some form of charging set. The charging set for the LRDG would likely be one of three things available to them: a small gasoline powered chorehorse, the vehicle generator from one of their vehicles, or perhaps a secondary mechanical generator driven either directly, or indirectly from the PTO of one of their vehicles. This latter option was often found in jeeps, during the war, mounted over the PTO assembly, between the two front seats.

Hope this helps a bit.

David
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Old 21-05-22, 23:50
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Lynn Eades Lynn Eades is offline
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Some ramblings:
I would tender the idea that most early war radio equipped vehicles were 6 volt and carried a petrol gen set (300 watt chorehorse or Brit equivalent?) The U.S. would have been the first of the allies to go over to a 12 volt vehicle electical system to cater for "in house" radio support. The belt driven (pto) generator in the Jeep was the same Autolite (different end plates) generator that was fitted in the Dodge Radio Car from circa 1943 (as well as late carriers)
These comments with respect to 12 volt Jeeps, from a thread in G503:

The W7 modification is in the February 15, 1945 SNL parts book.

I know the 12v PTO units were in production and Navy contract radio jeeps delivered by Willys-Overland in May of 1943.

The following TM for radio installations implies the conversion was in use at least by January 1944.

I think the 12 volt conversion in a WWII jeep was not so common until quite late in the war? (my comment)

Obviously, the problem with having a 6 volt vehicle and a 12 volt radio is that you need a second 6 volt battery. Keeping two separately used batteries evenly charged is not so simple. To manage this for soldiers that were in majority, farm types, required some extra care and skills.
To this day there are somewhat complicated systems in motor homes.
The radio op. would have used an hydrometer to check the state of charge of his batteries. This can be a bit vague, without familiarity.
For an LRDG radio op., with vibration, heat and evaporation, he would have been constantly mothering his batteries.

All the above stated from a position of "not much knowledge"
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  #8  
Old 22-05-22, 07:27
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Ron Pier Ron Pier is offline
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Lynn, like you without the benefit of huge knowledge, but from my own experience. My 1940 FFW Morris and Austin Tilly are both 12v which was supplied by twin 6v batteries wired in series.

The wireless batteries were kept charged by means of a PTO driven generator through a switchboard charging unit.

I would need to research other makes and models to confirm if this was the norm. Ron
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DSCF1543.jpg   DSCF1359.jpg  
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  #9  
Old 22-05-22, 10:20
Charlie Down Charlie Down is offline
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Default Charging Panel

Yesterday I got Brendan O'Carroll's new LRDG book, 'Fighting with the Long Range Desert Group' (which is excellent) and found a photo of a Wireless Chevrolet WA with panel on the side that could be a charging switch panel. I have now found 2 other WA photos with the same panel fitted. I have grouped a close up of the panel with the panel partially seen on a 1533X truck for comparison.
The panel has at least one knife switch and I assume based on other charging panels it would need 3-4 to make it work (see attached MKV Panel).
Hanno has suggested that the panel could be a main on off switch and posted the image attached. It doesn't match the original photo but has opened up more questions about the set up.
I've been working on the assumption, based on feedback from various wireless forums that the trucks would need a charging switch panel to manage the power and charging of the batteries. There are so far no known charging panels that fit the photo of the 1533X2 panel, so it has been presumed that it would be relatively easy to make one in a base workshop with a few suitable components that would fit onto a truck. I don't know why they didn't use a standard panel, they weren't the only wireless trucks in service in the Desert at that time. And I imagine they would have access to any if they were available. The early British Wireless trucks normally operated with 4 6 Volt batteries, and a separate battery for the vehicle. 2 batteries would provide the necessary 12 volts and the other 2 would be charged, usually by a chore horse or later on, a PTO driven generator. There is no evidence that the LRDG had that many batteries, although the spares could have been stored in a locker or in a box, ( I need to check the battery inventory) which would make sense as the Patrol was really about escorting the Wireless truck to a position to transmit intelligence back to base, and not having back up batteries would seem like a stupid idea, and the LRDG weren't stupid. It was suggested that the 1533X2 panel used knife switches on the charging panel based on the photos, and that they could be commercial not military. The LRDG did have some Chore horses on their inventory, but not it seems enough to equip all the Patrols and they seem to have been retained by HQ. Sorry for the random ramblings and thoughts. Its a serious test of my limited Wireless knowledge. I also need to stop calling the battery on the side step a spare battery, when it was clearly a Wireless battery in series!
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Charging panel2.jpg   Charging Panel 3.jpg   Charging panel knife.jpg   Brit Restoration 2.JPG  
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  #10  
Old 22-05-22, 13:14
David Dunlop David Dunlop is offline
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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
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Old 22-05-22, 14:34
Bruce MacMillan Bruce MacMillan is offline
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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.
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4pdtswitch.jpg   battery.jpg  
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  #12  
Old 22-05-22, 14:54
Bruce Parker Bruce Parker is offline
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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.
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Old 22-05-22, 16:59
Mike Cecil Mike Cecil is offline
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Default 12 volts

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
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Old 22-05-22, 18:48
Bruce MacMillan Bruce MacMillan is offline
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Quote:
Originally Posted by Bruce Parker View Post
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
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seaofsand.jpg  
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Old 23-05-22, 03:12
Charlie Down Charlie Down is offline
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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?
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BS_13_06.jpg  
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Old 23-05-22, 05:19
Mike Cecil Mike Cecil is offline
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Default No. of cells visible

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
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Old 23-05-22, 20:17
Charlie Down Charlie Down is offline
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Default LRDG Document

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?
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Wireless set up.jpg   Wireless care.jpg   knife switches.jpg  

Last edited by Charlie Down; 24-05-22 at 00:52.
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Old 24-05-22, 08:45
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Lynn Eades Lynn Eades is offline
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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.
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Old 24-05-22, 09:52
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Yes this is like the earth grounding kit I fitted to my Jeep many years ago, just to dress it up. Along with all the required filters and suppression parts that Lynn mentioned.
https://www.mvspares.com/WWII-JEEP-P...iijeep-418.htm

In line suppressors were fitted in the HT leads of motorcycles which was detrimental to their use, as magnetos don't work as well through a suppressor.

Ron
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Old 31-05-22, 13:29
Charlie Down Charlie Down is offline
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So, having thought about it and looked at other documents and photos, my current conclusion is that the LRDG used the same set up throughout the Desert campaign on all their trucks-Chevrolet WA, 1533X2 and Ford F30s. They used a WS11 High Power unit with Windom centre feed or sometimes end feed aerials on 16' duraluminium poles stowed on the trucks, and the 4' rod aerials for local (100 mile range) communication between Patrols. The power supply was fed through a 'Special' series/parallel switch for trickle charging/wireless use, from 2 standard 6 Volt batteries, one the truck battery, the other a 'booster' battery to provide the necessary 12 volts with the truck battery for the wireless. The 'booster' was mounted on the side step in front of the driver. During long periods of stationary Patrol, Road Watch, the Patrol would either take a chore horse to recharge the batteries or swap batteries with the other trucks in the Patrol. Very high levels of training were given to the signallers, this being the primary reason for the successful long range communication, not the limitations of the wireless. Very high levels of maintenance were given to the wireless and accessories throughout the Patrol. No information is given on what periods of the campaign chore horses are used, but it seems they were more common later on. I suspect that all the Chevrolet 1533X2 trucks, and most likely the CMP Ford F30s were fitted with wireless suppression fittings as standard, but on the WA's not so sure. Most likely the ones from the Egyptian Army would be suppressed, which would therefore be primary choice for wireless trucks, but not the ones sourced from the civilian dealership in Alexandria.

I've put a drawing together of the series/parallel switch based on the photos (not dimensionally accurate and most likely wrong with some details, but its something to work on!), and on the assumption its the same switch, but on the Chevrolet WAs it had a protective edge due to its external mounting on the outside of the rear body, but on the Chevrolet 1533X2 no protection was needed because it was mounted in the cab behind the Drivers seat. No photos found yet of its location on the Ford F30's, but its not externally mounted on the rear body, or in the cab, based on the limited number of photos showing those area of wireless trucks. It may be mounted in the plywood wireless compartment, or possibly in one of the tool boxes below the wireless compartment. Hopefully something will turn up.
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knife switches.jpg   SPECAIL SWITCH BOARD.jpg  

Last edited by Charlie Down; 31-05-22 at 14:21.
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