[ARC5] WOW

[Mike Morrow]

There has been some sort of misunderstanding.  I never said anything about control boxes.  The control boxes are neutral WRT system voltage.

In my first post today, which earthlink webmail server stripped of all line feed and made it difficult to read.  I wrote:

"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.

"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 adjust carbon mic excitation just to be able to install a stock-looking complete SCR-274-N in a 12 vdc jeep?"

I omitted the problem of any ready access to existing receiver 12 vdc dynamotors and the nonexistence of any interchangeable 12 vdc transmitter dynamotor.

It is immaterial that on the other side of the world some place was modifying under a semi-industrial program on order of some other government multiple copies of SCR-274-N modified for 12 vdc operation.  What the photos depict are obviously ersatz ad hoc one-of-a-kind installations without any industrial base producing them.  A local radio mechanic would not have access to the six different types of relays nor dynamotors for 12 vdc, not even the 12 vdc receiver dynamotor used on the Navy's R-3/ARR-2X and R-148/ARC-5X or one used in some USN interphones.  If he somehow magically conjured up such devices (relays and dynamotors), there is little doubt the effort would have been directed only toward the minimum number of components required to meet minimum requirements...not the luxury of a three-receiver and two-transmitter full SCR-274-N shown in Bill's photo.

The single receiver and transmitter system shown in Mike's photo is only slightly less challenging.  If the two transmitter-select relays in the one transmitter were made permanently mechanically closed, four different 12 vdc somewhat unique relays would still need to be found in addition to the likely unavailable 12 vdc receiver dynamotor and the nonexistent 12 vdc transmitter dynamotor.

I am surprised at the cavalier assumption that some ex-ham radio mechanic in the back of beyond could procure necessary parts (some of which did not exist) and effect such a conversion.  That is fantasy.  There is 24 vdc coming from somewhere in those jeeps.

Mike / KK5F