[ARC5] Jeep’s with ARC-5 radios

[Kenneth G. Gordon]

On 31 Jul 2021 at 11:40, MARK DORNEY via ARC5 wrote:

> I think we´ve established that the only way to practically run an
> ARC-5 set up on a WW2 Jeep is to run it off an APU or to have a
> battery bank set up somewhere to provide 24 volt power to the set,
> since there was no conversion kit for the WW2 jeep to run 24 volt
> power, and Jeep´s and other light vehicles weren´t converted to run a
> 24 volt electrical system until the 1950s.  More than likely this
> generator or APU was run separately from the vehicle, perhaps towed
> behind it on a trailer.

I don't agree: small 24 V APUs were available from quite early on in WWII. They would not 
have needed to be "towed". The one I am familiar with could have very easily be set down in 
the Jeep's passenger seat area.

> Batteries could be charged together or
> separately, depending on what was available to charge them.  So what
> is needed now are pictures of the power set-up. It would have to be
> pictures, since there was no official 24 volt set up authorized by any
> military until well after the war. Even the PTO radio Jeep's purpose
> built during WW2 were 12 volt.

Although I agree with your assessment for the most part, I am also trying to envision what I 
would have done in a similar situation. I also agree completely that at this point in our 
discussion we should consider the primary power source. What was it most likely to be?

First of all, I cannot imagine that this setup would have been used for an extended period of 
time, like to monitor used frequencies, mimicing a control tower. IMHO, it would have been 
used for short periods when the aircraft involved were assembling, taking off, and returning 
from a mission. I think it would have been called upon when needed, and not operated 
continuously. If this is true, this, alone, would indicate battery power.

Secondly, it seems to me that the technicians involved must have wanted to come up with 
the simplest method of getting the job done. This, to me, would preclude doing any extensive 
modifications, or in fact ANY modifications, to the equipment itself. There is also the fact that 
modifications to military equipment was frowned upon.

Taking only these two factors into account, it would seem to me that the simplest solution 
would be simply two 12 V or four 6 V well--charged batteries. A pair of large 6 V batteries 
were used in the 10 kW PE-95 generator to "motor" the generator for starting.

The fact that the passenger's seat is not there would tend to lend credance to this scenario.

The second less-simplest method would be the use of a 24 V APU, which, given that this 
Jeep was being used at a forward air-field, these APUs may have been available. These 
units were commonly available some time during WWII. I remember I had one once: a small, 
yellow job using a single-cylinder engine which may have been a 2 cycle. It was a rope start 
unit. As I remember it (dangerous at my age) it was capable of around 500 watts.

These were small enough to be set down in any Jeep where the front passenger seat would 
have been.

It would really be nice to see a photo of the interior of this Jeep, or one like it, as you have 
mentioned.

BTW, I have 12 V dynamotors here which were used during WWII, I have two types, one 
normally used in a receiver, outputting 250 VDC, used, I believe, in the BC-603/683 (?) 
receivers (DM-35 maybe), and those normally used in the accompanying transmitters, 
outputting 600 VDC. I am sure that although these were from tank-radios, I would think that 
they would have been available in Iran at the time. Even so, using them would require 
modifying the "ARC-5" equipment, and at this point, I don't think that would have been done.

> "The game is afoot"

Yes, it most certainly is. I am thoroughly enjoying this discussion as it shows, again, how our 
radios were used in actual combat situations. The technicians, many of whom were hams 
BTW, were ingenious and used what they had. Good for them.

Ken W7EKB