[ARC5] Jeeps with Radio Equipment

[Mike Morrow]

> 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 will not speculate from where the 24 vdc comes.Mike / KK5F
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