Radio Compass Indicator I-81-A of SCR-269-G and AN/ARN-7

The I-81-A Radio Compass Indicator (aka Pilot's Bearing Indicator) is a component of the Radio Compass SCR- 269-G system (which evolved into the AN/ARN-7), used during WWII.  According to the Airborne Radio Equipment Handbook of the Air Service Command dated 1943, this system appeared in versions of the US Army Air Force bombers B-17, B-24, B-25, B-26, B-29, and transports C-46, C-47, and C-54, as well as in any models of these aircraft used by the US Navy. The system was designed primarily to be used as a navigational instrument, and this is the indicator which appeared on the pilots instrument panel to provide directional indication for the signal being received from the transmitting installation, e.g., an airfield or other navigational beacon. The equipment is basically a 15 tube superheterodyne radio receiver with the addition of certain essential circuits necessary for radio compass operation. The equipment is designed for remote control operation and may be installed with provisi