[Milsurplus] RC-12 Oscillator Equipment

[Mike Morrow]

I have edited a post I made on 13 May 2015 to correct a couple of typos and add some dates.

Mike Hanz wrote:

> I have a photo of it in a B-15 bomber at 
> http://aafradio.org/flightdeck/1935/B-15-2.JPG

The Signal Corps General Catalog of 1940 describes this system as:

RC-12 Oscillator Equipment

There were six variations of the Oscillator unit, beginning in 1933:

BC-GL-183
BC-GM-183
BC-RA-183
BC-RB-183
BC-RC-183
BC-RD-183.

The calibration chart is MC-132.
The calibration chart case is CS-45.
The oscillator mounting is FT-103.

It is described in the catalog as providing for reception of unmodulated signals as an optional accessory to these Observation and Liaison sets:

SCR-202     (1933:  BC-AA-179 receiver, USN Type GM transmitter)
SCR-AA-185  (1934:  BC-AD-219 receiver, BC-AA-191 transmitter)
SCR-AB-185  (1936:  BC-AF-229 receiver, BC-AA-191 transmitter)
SCR-AA-187  (1934:  BC-AD-219 receiver, BC-AA-191 transmitter)
SCR-AB-187  (1935:  BC-AE-229 receiver, BC-AA-191 transmitter)
SCR-AC-187  (1936:  BC-AG-229 receiver, BC-AA-191 transmitter)

The BC-**-183 Oscillator got its power from the 5-pin connector on the bottom of the receiver system junction box.

Although it is not described as a frequency meter, RC-12 included an 8-inch tall calibration chart MC-132 that was created for and serial-numbered to each individual unit.  This chart is 32 *feet* long!  That indicates the intended function of RC-12 was of greater scope than simply providing a heterodyne oscillator for CW reception.

Mike / KK5F