Tube network radio receiver "SI-646".
Tube radios.DomesticThe network tube radio receiver "SI-646" in 1936 was produced in a limited series by the Ordzhonikidze Moscow Electromechanical Plant. The `` SI-646 '' radio receiver (Network Individual, 6-circuit, 4-tube, 1936) is a superheterodyne type broadcasting receiver with full AC power supply, mounted in a common box with a dynamic loudspeaker and rectifier. The receiver belongs to all-wave, since in addition to receiving long-wave and medium-wave stations, the receiver can receive short-wave broadcasting stations. The receiver covers the ranges: 19 ... 50 m (shortwave), 200 ... 550 m (medium wave) and 714 ... 2000 m (longwave). As the name of the receiver itself shows, it has 6 resonant circuits, of which 2 are the received frequency circuits and 4 are the intermediate frequency circuits. The role of the local oscillator, the first detector and mixer is performed by the CO-183 pentagrid. The radio frequency circuits, including the local oscillator circuit, are tuned by variable capacitors, the rotors of which are mounted on a common axis and rotated by a common vernier. The intermediate frequency is amplified by a high-frequency pentode of the SO-182 type. The intermediate frequency voltage, after amplification by the SO-182 lamp, is supplied to the diode part of the CO-185 double diode-triode, the triode part of which operates in the first stage of LF amplification. In the final (second) stage of bass amplification, the CO-187 pentode operates. The receiver has manual as well as automatic volume control, tone (timbre) control, selectivity control. The receiver can also be used to play back a recording with an external EPU.