I got some declassified CIA documents regarding the A-12 crash near
Wendover Utah. In the 400+ pages, there is a chronological log of the
events of the flight. This particular page notes the radio stations
and beacons used with the planes ADF. Of interest is a beacon on
377KHz, noted as both XTS and STB.

http://www.lazygranch.com/images/cia..._earth_377.jp2
You will need irfanview with the plugings to view this document.
http://www.irfanview.com/

Any ideas on where this NDB is located? Note that many of the beacons
on the list are now history. [Austin was converted to DGPS] so this is
probably an historic beacon as opposed to operational.