LP2A Carrier Radio Installation

[Ian Hall]

G'day Everyone.
I am new to the forum, but I have owned an Australian LP2A Carrier (2930) for many years. 2930 is fitted with a No. 11 radio and an original wooden battery box (with "6V" on the terminal block) as per the manuals.

My question is how to wire up the battery for the radio ? The radio is 12V negative earth, while the Carrier is 6V positive earth. The manual for the No. 11 set shows a "Connector Low Tension" with leads to two 6V batteries which are connected in series to give 12V. In the Carrier manual, the only clue is that radio cable should be plugged into the inspection light socket. I assume the idea was that for charging the vehicle and radio batteries were in parallel, while for radio operation, the batteries were in series via some sort of two position plug. However, this cannot work with one being positive earth and the other negative earth.

Does anyone have a wiring diagram for the radio battery cables ?
Did this require the Carrier to be changed to negative earth ?

Regards,
Ian

[Ron Pier]

Hello Ian and welcome. I'm no authority on Australian carriers but I'm surprised that they were Poss earth. All our stuff back then was Neg earth. But never the less, the 12 V (2x6V) supply is plugged into the power supply unit (bottom right) and I would think a separate charging system would be required like a Chore Horse generator as installed in my Canadian MK2 for its 19 set.(It's a bloody heavy generator stowed in the rear left here) ,

The 11 set installation in my Morris truck has 2 pairs of 6V batteries and one pair would be on charge through a switchboard whilst the other pair are supplying the wireless. Ron

[Mike Kelly]

Maybe they got around the polarity problem by insulating the radio and its power supplies from the carriers hull ?

Was there another 6V battery somewhere apart from the carriers own battery ? Maybe there was a split charging system and they switched the second battery into series with the carriers battery when the radio was required ?

[Ian Hall]

Thanks to Ron & Mike for your replies.

The Australian LP Carriers followed the Ford USA design with positive earth electrical systems. I do have a Chore Horse generator, but there is no indication in the manuals or stowage provision to carry the generator on the Carriers.

Ron - I see that your No. 11 set has two wires going to the power plug for 2 x 6V batteries, whereas mine has only a single wire to suit a 12V battery.

Mike - I did consider if the radio could be insulated from the hull, but the wiring in the radio is connected to the radio frame in many places and insulating the whole radio from the Carrier hull would give a 12V potential between the radio case and the Carrier hull which would be unsafe. I have the wooden battery box for a second 6V battery installed as per the manual and you could design a wiring harness with a two position plug and socket. Plugged in one way the 6V batteries would be in parallel for charging and the other way in series for radio operation, but this still does not solve the polarity problem.
Regards,
Ian

[Mike Cecil]

Ian,

Welcome to the forum. I still have several shots of your carrier display at the Bicentennial airshow in 1988 in my photoalbum. Very nice job.

This may (or may not) help, but its the only carrier file associated with communications that is listed on Recordsearch. You can order a copy on-line through recordsearch. Use the Barcode number (I've placed that in bold) as the quickest way to bring it up on the Recordsearch screen:

Item details for: MP508/1, 325/702/776

Title
[Machine Gun carrier - internal communications placing of crew in vehicle]
Contents date range
1942 - 1942
Series number
MP508/1
Click to see which government agency or person created this item.
Control symbol
325/702/776
Citation
NAA: MP508/1, 325/702/776
Item barcode
1079114
Location
Melbourne
Access status
Open
Date of decision
20 Dec 1993
Physical format
PAPER FILES AND DOCUMENTS (allocated at series level)
Date registered
20 Dec 1993

Best regards

Mike

[Ron Pier]

Ian it makes no difference if you have one 12V battery or two 6V batteries as the two 6V batteries will be wired in series to create one 12V. As on my Tilly here for instance which is a normal 12V vehicle. Back then it was common to have both 6V and 12V vehicles so 6V batteries were quite common.

The two cables in the plug will be for the pos and neg terminals on the battery.
Ron

[Lynn Eades]

Ian, Does this help? and I might be corrected here.
The standard Universal carrier (MkI or MkI*) (English or Canadian) had a 6 volt battery on the left rear floor. It was a dedicated carrier battery for the starting and running of the carrier along with its standard fittings (lights , horn etc)
It also had a battery box at the rear that carried two 6 volt batteries that were dedicated radio batteries. These batteries were charged with the likes of a chore horse charger (6volt during WWII)
The batteries were obviously hooked up to the radio as an entirely independent circuit. They would possibly have been disconnected from the radio for charging (connected in parallel for charging and series for radio operation)
On later carriers like my Armoured O.P. MkIIIw, there was stowage provision for the gen set, on the left rear.
Also if it helps, the (later)19 set is rubber mounted. (I know very little about radios)