Control Unit C-4, of ARN-7 Automatic Radio Compass, B-17, B-24, B-29 Nick Fighter but not the Royal Air

but not the Royal Air Force since it didn't come into existence until 1918)

The screw (H) (two) serves to fasten the instrument to the mounting plate

dated 1953

The cover page page was missing

Control Unit C-4, of ARN-7 Automatic Radio Compass, B-17, B-24, B-29 Nick Fighter but not the Royal AirHere is a WWII era Control Unit for the ARN 7 Automatic Radio Compass system used for direction finding and homing. The receiver function tunes from 100 1750 kHz across 4 bands, which were selected by rotating the center knob below the frequency band window. The center knob rotates a flexible shaft connected to a rotatable loop antenna. The ARN 7 system (see diagram), were one of several generations of radio navigational systems installed in an