[MRCA] [ARC5] Jeeps with Radio Equipment

[MARK DORNEY]

To keep the Jeep batteries charged, a generator of some sort needs to be mounted somewhere in the Jeep, along with some sort of voltage regulator to keep the batteries from being overcharged . The WW2 Jeep  factory set up, at least initially, for a 12 volt MB or GPW involved installing a second 6 volt battery, generator and voltage regulator. This was later replaced by use of a 12 volt system for the entire vehicle, as the dual battery system added both cost and complication ( there isn’t a lot of room to add a second electrical system in a Jeep). The same is true for the larger 3/4 ton WC series ( the second battery was installed in the front, passenger side tool box, along with the radio connection box in the factory set up). But especially in the Jeep, there simply isn’t any room to do add too much to the vehicle. It is true that the Jeep was set up to accept a PTO, but the only issue Jeep that actually had an issue PTO was the GPA Amphibian, and they were relatively rare. The only other way I could think of to operate the radios without modifying them would be to have either a gas generator mounted, or scrounged aircraft APU mounted in the Jeep or towed on a trailer behind the Jeep, and I see neither in the photo ( perhaps there is a trailer that went with this Jeep that isn’t in the photo ).  Also, ARC-5/SCR-274 was designed for aircraft use. The radio gear, with it’s thin aluminum casing,  isn’t designed to take the beating it would get on the ground in the field. That alone points more to a ad-hoc radio installation devised and done in theatre. Take a close look at the way the aircraft radios are mounted in the Jeep in the photo. It looks “home-made”. This mount was done in theatre to fill a specific need at the airfield. 

It is easier and more likely that the aircraft radios were modified to operate on 12 volts than the Jeep converted to operate on 24 volts. An enterprising Ham ( and we all know that Ham operators were highly sought after by the US Navy and USAAF during WW2 ) more than likely converted the radios in this case to 12 volt. Take a look at what radios in this series are left for sale today, and we’ve all seen evidence of enterprising Hams modifying these radios to suit their own needs. That was not limited to post-war operation. There are photos of scrounged aircraft radios 
 installed in airfield Watch Stations at USAAF airfields in England during the war. These radios supplemented the airfield’s radios ( there was a transmitter and receiver, I believe a BC-639 and BC-640, at each field, along with another station set up to aid radio navigation in bad weather in the TO&E for each airfield ). These aircraft radios were scrounged from supply, more than likely from aircraft that came back too badly damaged to be put back in the air. Of the set ups I’ve seen pictures of in Watch Stations, there is a battery bank of four, 6 volt batteries set up to power these radios. I did not see how these batteries were re-charged, but more than likely there was some sort of electrical battery charger scrounged for purpose stored somewhere at the watch station, and somebody on a shift who’s duty it was to regularly recharge these batteries. 

Mark D. 
WW2RDO

“In matters of style, float with the current. In matters of Principle, stand like a rock. “.   -   Thomas Jefferson 

Sent from my iPhone

> On Jul 29, 2021, at 4:31 AM, Robert Downs <wa5cab at cs.com> wrote:
> 
> Mark is correct about the probable date that the photo was shot and the Jeep is either an MB or a GPW with 6 volt internal electrical system.  It has a 2-piece wind screen.
> 
> However, although the Command Set receivers can, with a little rewiring and/or tube swaps, be operated from either 12 or 6 volts, the transmitters cannot.  At least within the limits that the AAC would have imposed.  There were never any 6 or 12 VDC relays or transmitter dynamotors built and in the supply chain.  Although I have heard that there was a 12 volt conversion kit procured in very small quantities, I have never heard that there was a 24 volt kit.  But the Jeep has to have at least a 24 volt battery in it somewhere.  Most likely, as it could have been requisitioned at the time, the Jeep has one of the auxiliary PTO driven generator and batteries installed.  The angle at which the photo was taken hides the evidence.
> 
> Robert Downs
> 
> 
> -----Original Message-----
> From: arc5-bounces at mailman.qth.net [mailto:arc5-bounces at mailman.qth.net] On Behalf Of MARK DORNEY via ARC5
> Sent: Thursday, July 29, 2021 01:57
> To: Bill Pileggi
> Cc: arc5 at mailman.qth.net
> Subject: Re: [ARC5] Jeeps with Radio Equipment
> 
> The negative of the photo was received in 1950 from some unit’s records. The photo was taken in Iran, more than likely sometime during WW2, since the B-24 and it’s subtypes we’re removed from  service when World War Two ended. 
> 
> Mark D. 
> 
> “In matters of style, float with the current. In matters of Principle, stand like a rock. “.   -   Thomas Jefferson 
> 
> Sent from my iPhone
> 
>> On Jul 29, 2021, at 1:41 AM, Bill Pileggi <wpileggi at juno.com> wrote:
>> 
>> Slightly over 10 years ago (June 2011) , there was a mention on this list of a photo of a Jeep with ARC's in the rear deck. At the time, they would have provided a link. Don't know what the link is now... Nobody seems to have brought it up... As a bonus, there's a B-24 in the background.
>> 
>> So, I'm attaching. It's about 89 Kb.
>> 
>> Bill KA3AIS
>