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Rotary Discharger - AWA, Spark Radio Transmitter, circa 1914 Object Reg. No: ST 015463

Summary:
Rotary discharger, part of spark radio transmitter; made by Amalgamated Wireless Australasia Ltd. for use in the Marconi Telefunken System for ship-to-shore and ship-to-ship radio communication.

The device is connected between a capacitor and an inductor. The capacitor is charged to a high voltage from a alternating current source, such that the gap will break down causing a spark to cross from one copper electrode to the other via a toothed wheel. The gap is adjusted such that the gap breaks down when the spacing is close to the minimum. The wheel is driven by a motor (missing). As the wheel rotates, the spark is interrupted to produce an audible tone in the transmission. A morse code message is produced by keying the spark on and off producing a series of tones (the dots and dashes of morse code).
Description:
Metal and ebonite device on wooden table on wooden base. Wooden table top and base have elliptical holes ( to allow connection to motor (missing) via a belt (missing).
Device consists of a toothed wheel on an axle with pulley at other end. The wheel lies between two adjustable electrodes mounted on ebonite blocks, which are connected to terminal screws mounted on ebonite cylinders. The electrodes show darkening and erosion due to use.
Acquisition Information:
Donation from Amalgamated Wireless (Australasia) Ltd., 1924
Discipline: Technology
Dimensions: 345 mm (Height), 271 mm (Width), 512 mm (Length)

More information

Tagged with: radios, radio dischargers
Themes this item is part of: Information & Communication Collection, Early radio: transmission and reception, 1900 - 1914
Primary Classification: COMMUNICATIONS
Secondary Classification: Radio
Tertiary Classification: transmitters
Inscriptions: Metal plate on top: MADE IN AUSTRALIA / AMALGAMATED WIRELESS (AUSTRALASIA) LTD / MARCONI TELEFUNKEN SYSTEM / SYDNEY, NSW. No 97-422
Embossed in wooden top: TESTED B7-A
Metal plate on base: AUSTRALIAN MANUFACTURE
Stamped underneath base: (rubber stamp illegible but overwritten) 028? / 59?58
Manufacturer: Amalgamated Wireless (Australasia) Ltd., Sydney, New South Wales, Australia, circa 1914
Patentee: Marconi's Wireless Telegraph Company, England, Great Britain, circa 1914

Patents were probably held by both telefunken and Marconi.
Bibliography:
  1. [Book], Mr Peter Jensen, In Marconi's Footsteps, 1894 - 1920, Kangaroo Press, 1994, 1994

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