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).
Physical 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.
More Information
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Collecting Areas
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Acquisition Information
Donation from Amalgamated Wireless (Australasia) Ltd., 29 Dec 1924
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Manufacturer
Amalgamated Wireless (Australasia) Ltd., Sydney, New South Wales, Australia, circa 1914
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Patentee
Marconi's Wireless Telegraph Company, England, Great Britain, circa 1914
Patents were probably held by both telefunken and Marconi. -
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
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Brand Names
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Classification
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Category
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Discipline
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Type of item
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Overall dimensions
512 mm (Length), 271 mm (Width), 345 mm (Height)
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Maximum dimensions
515 mm (Length), 270 mm (Width), 335 mm (Height)
Measurement From Conservation.
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References
[Book] Jensen, Peter. 1994. In Marconi's Footsteps, 1894 - 1920., 1994
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Keywords