[ARC5] BC-453 in the SCR-274N Configuration

[Mike Morrow]

>  The manual shows a Detrola LF receiver mounted
> on the lower right side of the cockpit.

That's the Detrola 438.  There are at least six different BC-1206 models...A, B, C, CM, CM2, D.  The  BC-1206-A model is the same as the Detrola 438.

> The BC-1206 was Setchell Carlson Model 524. The
> Model 512 was the R-76/ARR-13. It was similar to
> the 1206 but had a switch that when pulled out set
> the radio to 276 Kc.

The R-76/ARR-13 has other very significant differences.  It is wired for 12 vdc filaments and requires an HV B+ supply of about 150 vdc.  It was made for use in light observation aircraft like the Stinson series that had a 12 vdc electrical system.  It was most commonly paired with the RCA/Continental AVR-20A1 HF receiver, AVT-112 HF transmitter, and AVA-126 vibrator power supply.  The instruction manual for the R-76/ARR-13 instructs how to wire it to the AVA-126.  It is no surprise that the R-76 beat out the RCA AVR-15 beacon band receiver.

The national standard LF tower frequency (often paired with 3105 kHz) that the pull swich on the R-76 normally selected is 278 kHz.  It tunes all three front-end circuits to allow instant swap between 278 kHz and the frequency set on the dial.

There is a very interesting JAN nomenclatured beacon band receiver, the AN/CRR-1 (Setchell-Carleson Model 519).  It is powered solely by dry cells and uses 1.5 v filiment tubes.  It was to be packed with the SCR-578-* Gibson Girl 500 kHz emergency transmitter for North Atlantic flights from North America to Europe.  The AN/CRR-1 potentially allowed two-way comms from rescue aircraft (on a different frequency) to a downed crew.  The only set I've seen is the one I have, but it is described in USAAF documents of the late WWII era.

> Another important use of the BC-1206 and R-76 was
> they were used for ferry flights from the factory to
> the facility that installed the radios.

That does not apply to the R-76/ARR-13, which requires a 12 and 150 vdc power supply.

Mike / KK5F