[ARC5] Jeeps with Radio Equipment

[Captain D.]

Radio modification of the transmitters for the ARC-5/ SCR-274 is extremely difficult, but not impossible.  So modification would really depend on the motivation of the tech doing the mod, and his ability to find the parts needed.  If the regular USAAF/USN  radios were not available, then use of an SCR-274/ARC-5 is brought into play.  The photos of the modified vehicles do not positively show a power source, and a 24 volt kit to convert the vehicle electrical system was not available for the MB/GPW ( or the WC-series 3/4 ton vehicles, for that matter) until well after WW2 ended, and there were no 24 volt electrical system 1/4 or 3/4 ton wheeled vehicles factory produced for field use until the 1950s..  I agree that in such a situation, converting the radios to 12 volt is not likely, since parts to do so would not be readily at hand.  So we're left with getting a scrounged generator/APU to supply the 24 volts needed to power the radio/ recharge a bank of batteries to provide the necessary 24 volt power to the radio in the picture.  There is no APU/generator anywhere in the pictures that have been posted to far. The only assumption that can come from that is the equipment used to power the radios/recharge the battery bank was supplied by something not in the pictures.  A trailer mounted generator/APU makes sense, especially and APU.  The APU was already in USAAF inventory, and was commonly used for bomber aircraft.  The APU could be connected to the radios using a theatre made cable with plugs and sockets gotten through regular supply channels, or scrounged from damaged/not airworthy aircraft.  Mark D.WW2RDO   "Courage is not having the strength to go on.  Courage is going on when you don't have the strength."   -  Theodore Roosevelt  Sent from my AOL Desktop  .In a message dated 7/31/2021 12:59:22 PM Eastern Standard Time, kgordon2006 at frontier.com writes: 
On 31 Jul 2021 at 16:43, Mike Morrow wrote: > The radios may not be ARC-5, SRC-274 or ARA radios. They may be an> earlier> look-a-like that ran on 12 volts.Rule that out positively. > There were no such radios anywhere anytime in military service...ever> (except the R-148/ARC-5X and its rack... a 14 vdc version of> R-23A/ARC-5).  When use of an aircraft MF/HF command set was required in> a 12 vdc environment, the USAAF used the SCR-A*-183 and the USN used the> appropriate RU/GF system.> Either that, or parts were scrounged and> radios were heavily modified.This suggestion lacks credibility.The full> SCR-274-N installation shown in Bill's photo looks like one pulled> "lock, stock, and barrel" from a USAAF aircraft with no attempt to> tailor it to just whatever HF capability that jeep may have required. > (Certainly it did not need a beacon band receiver.)  Just how great> would be the motivation to locate ten rather uniquely configured 12 vdc> relays of six different types, install them in five different> components, rewire filaments in six different components, and rewire> carbon mic excitation just to be able to install a stock-looking> complete SCR-274-N in a 12 vdc jeep?  Occam's Razor indicates that the> ONLY reasonable and logical conclusion is:  That SCR-274-N is being> supplied 24 vdc.Mike's photo of a custom single receiver single> transmitter installation provokes these comments:1.  The transmitter> control box appears to have a built-in key on its top.  Only the ATA> CBY-/CCT-23243 and SCR-274-N BC-451-A control boxes have a key...the> very rare C-29/ARC-5 does not.  That indicates the equipment is ARA/ATA> or SCR-274-N.2.  ALL components have black paint.  That indicates the> equipment is ARA/ATA or EARLY SCR-274-N.It is equally unlikely that this> equipment has been reworked for 12 vdc for the same reasons I cited> above except that only six 12 vdc relays of six different kinds would be> required.  Anyone performing such a quixotic feat should also have> realized that a single-transmitter system using only VOICE emission> requires NO transmitter control box.  Some post-WWII USN training> aircraft used only the T-19, R-23A, and R-26/ARC-5.  There were C-125> controls present for the R-23A and R-26, but the ONLY transmitter> control was the instructor's PTT switch.My conclusion:  The sets in each> of these photos without any doubt are being supplied 24 vdc. I absolutely agree with this statement!!! >  I will not> speculate from where the 24 vdc comes.Mike / KK5F Ha ha! **I** will! :-) Ken W7EKB______________________________________________________________ARC5 mailing listHome: http://mailman.qth.net/mailman/listinfo/arc5Help: http://mailman.qth.net/mmfaq.htmPost: mailto:ARC5 at mailman.qth.net This list hosted by: http://www.qsl.netPlease help support this email list: https://www.qsl.net/donate.html
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