Aircraft Direction Finder Receiver Type AD16, by Marconi Company, London, c. 1928

Aircraft Direction Finder Receiver Type AD16, consisting of a High Frequency (H.F.) Amplifier and Supersonic Amplifier with vertically-mounted panels in a varnished cloth-covered case with removable front and rear panels. With three Bakelite tuning dials mounted on upper part of front vertical surface of case, marked Search Coil Tuning (scale 90,0,90), Coupling Coil (scale 180-0), Closed Circuit Tuning (scale 180-0). With power supply plug, headphones plug and assorted terminals on vertical side of case. Removing the rear panel reveals the full extent of the assorted interior coils and components. Removing the front panel reveals the interior including ebonite surfaces of the H.F. and Supersonic Amplifiers. The HF Amplifier has seven 'Type Q'/'Type V24' radio valves mounted vertically, two unscaled Bakelite tuning knobs and a celluloid plaque detailing Low Tension (L.T.), High Tension (H.T.) and other assorted power options. The Supersonic has five 'Type Q'/'Type V24' radio valves mounted vertically, a Bakelite emitter tuning knob (Dull, Bright), a large scaled Bakelite tuning dial (scale 0-10) and a celluloid plaque detailing Low Tension (L.T.), High Tension (H.T.) and other assorted power options. With associated photocopied leaflet.