[Milsurplus] Info on BC-1206C usage?

[Mike Morrow]

Marc wrote:

>Needed for a magazine article: information on how the military used
>the BC-1206 beacon receiver. 
>
>With its light weight, compact design, and ability to run directly
>off the plane's  28-volt system  without a dynamotor, it's obviously
>intended for light aircraft. And the manual advises on retrofitting
>it (mount it in a standard instrument opening using the screws supplied
>or fabricate a metal strap and attach to the plane at any convenient
>spot).
>
>Which planes were these sets typically used on? Were they ever supplied
>on certain planes as original equipment? Does someone have a picture of
>a 1206 as installed in a plane.

Marc, here's probably more than you want to read.

The BC-1206 is part of a series of beacon-beacon band radios.  

It's true that many would be used temporarily for ferry service, when an
aircraft's final radio installation had not been made.  Below I describe
some key points of civil aviation radio usage from the 1930s to 1950s.
Many of these receivers have permanent labels warning ferry pilots or
other personnel not to remove the unit from aircraft without authorization.

Yet other aircraft had these simple beacon band sets installed when
the normal radio installation did not provide a beacon band receiver
like the BC-453.  Many USAAF fighter aircraft had only the VHF-AM
SCR-522-A set installed, so a BC-1206 would also be installed as
part of the permanent radio gear.  You'll see below links to photos
of the P-38J and P-51D which show permanent BC-1206 set installations.
In those photos, the set is either a Detrola Model 438 or BC-1206-A, which
is a little different in shape to the Setchell-Carlson BC-1206-C series.

Here's a list of most, but far from all, such military receivers (all of
which I have in my collection):

A.  28 vdc power, supplied by aircraft dc bus:
1.  BC-1206-A   (Detrola Model 438)
2.  BC-1206-B   (Identical to BC-1206A, but made by Warwick)
3.  BC-1206-C   (Setchell-Carlson Model 524, but two different variations)
4.  BC-1206-CM  (Setchell-Carlson Model 524, yet another C model variation)
5.  BC-1206-CM2 (Setchell-Carlson Model 524, yet another C model variation)
6.  BC-1206-D

B.  14 vdc and 250 vdc power, supplied by RCA AVA-126 vibrator supply:
1.  R-76/ARR-13 (Setchell-Carlson Model 512)
    Note:  Used with 14 vdc RCA AVT-112, AVR-20A, and AVA-126 HF set.
           The military chose the more-versatile S-C Model 512 over the
           RCA AVR-15, which is larger (same size as the AVR-20A), has
           no RF stage, and no 278 kHz tower frequency pre-set.

C.  1.5 vdc and 135 vdc power, supplied by dry batteries:
1.  AN/CRR-1    (Setchell-Carlson Model 591)
    Note:  Used with SCR-578 (BC-778) 500 kHz beacon transmitter to give
    distressed Arctic aircrew the capability of receiving MF transmissions
    from rescue aircraft.
2.  Type 185/186 (Boonton Radio Corporation)
    Note:  Purchased for US Navy training aircraft use.
 
Photo of BC-1206-A or Detrola Model 438 in P-38J:
http://www.zenoswarbirdvideos.com/Images/38cptR.gif
 
Photos of BC-1206-A or Detrola Model 438 in P-51D:
http://p51h.home.comcast.net/~p51h/sig/TO/01-60JE-25.pdf

>From the 1920s to the 1950s, a simple beacon band receiver was one of the
most important radios that an aircraft could have.

Civil airport towers used the standard tower transitter frequency of 278
kHz to provide airport information and serve as the tower-to-aircraft channel.
The aircraft-to-tower transmitting frequency was 3105 kHz (and sometimes
6210 kHz).  Many civil aviation light aircraft sets used one of the many 
commercially available 278 kHz-R/3105 kHz-T sets (like GE AS-1B), which cost
typically cost about $200 in 1946 ($2000 in 2011 dollars).  The MF receivers
always covered the 200 to 400 kHz beacon band, and often also covered the AM
broadcast band and had a simple loop antenna for direction.  In the early 1950s,
3105 kHz was replaced by 3023.5 kHz for this service, and sometimes a different
frequency than 278 kHz was used by the tower.  The beacon band receiver by
itself allowed radio navigation by following one of the four directional
beams transmitted from A-N Adcock beacons of that era (most of which shut
down by the late 1950s).

Even if the aircraft owner did not want to pay the for one of these two-way
sets, he could opt for a simple beacon band only receiver (like the Motorola
Airboy) for about $30 ($300 in 2011 dollars).  For that money, the pilot could
navigate the Adcock beacons and receive the informational broadcasts on an
airport's tower frequency.  In civil aviation light aircraft use, any surplus
BC-1206 would not have been too usable because few such civil aircraft had
28 vdc supplies.

Many military training aircraft of that era were permanently equiped to function
on civil aviation frequencies as just described.

The USN had less need for such receivers, since carrier aircraft returning to
their carrier used the ZB/YE-YG (AN/ARR-1 and -2) VHF homing system.

Mike / KK5F