[Milsurplus] BC-1206-B IF bandwidth

[Mike Morrow]

Neil wrote:

> The receiver covers 200-400 KHz ... I think it was intended as a NDB beacon
> receiver only...

Just the opposite, actually.  It was intended for DIRECTIONAL beacons of the Adcock A-N type from which four traffic lanes/beams originated, not necessarily 90 degrees apart.  A lane/beam could be flown by flying a path that merged A and N reception around the path to a solid continuous tone...no loops or indicators required...just the pilot's ears.  In addition, control tower AM transmissions could be copied...278 kHz was most common, paired with aircraft AM transmission on 3105 kHz (typical).  This whole system was in place by the mid-1930s.

Directional beacons were essentially extinct in North America by the end of the 1950s.  Most became simple non-directional beacons that require aircraft RDF or ADF sets with loop in order to be useful as a nav aid.  A simple receiver like the BC-1206-* has no navigation value unless the received beacon is directional.

For example, a typical WWII-era light-aircraft 12-vdc installation in a Stinson L-5 used:

RCA/CR&TC AVR-20-A1 2300 to 6700 kHz receiver (plane to plane),
RCA AVT-112 2500 to 6500 kHz transmitter (plane to control tower),
Setchell-Carlson Model 512 (R-76/ARR-13) 200 to 420 kHz with 278 kHz pre-set
  receiver (control tower to plane, directional beacon),
RCA AVA-126 12-vdc vibrator power supply.

That R-76 beacon band radio served vital communications and navigational purpose.

Mike / KK5F