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Cover For Multiple Tuner, by Marconi Company, England, c. 1907

Inventory Number: 74506

74506-1t 74506-2t

Date: c. 1907

Maker Details: Attributed to Marconi's Wireless Telegraph Co. Ltd.

Inscription: None

Size: 435 x 160 x 130 mm

Materials: Mahogany, brass, glass.


Glass-topped mahogany cover for multiple tuner, with brass components.

For the magnetic detector to work effectively in a system designed to respond to the principles of tuning as defined by Marconi, another device was required; the multiple tuner met this need. The Multiple Tuner, patented in 1907, was invented by one of the Marconi Company's most prolific engineers C.S. Franklin. It was in 1904 while he was serving in Russia that Franklin sent home sketches and drawings of the first disc capacitor. This concept was rapidly developed to incorporate variable inductances, and in its ultimate form was to be known as the multiple tuner. In conjunction with the magnetic detector it was adopted as standard equipment for ship-to-shore service and remained so for many years. The detector being of low resistance, works on current rather than voltage effects, and hence in this receiver, capacity effects predominate and inductance effects are small. The instrument is designed to tune to all wavelengths from 30 ft to 8000 ft. The apparatus was suitable for ship or shore installations in conjunction with the magnetic detector, which was connected to the terminals, marked 'detector'. When the switch on the multiple tuner was at 'tune', the magnetic detector was placed in series with a condenser which was coupled inductively with another circuit called the intermediate circuit. This intermediate circuit was again coupled with the aerial circuit. Each circuit in practice was adjusted to the wavelength being received. This arrangement gave sharp tuning.

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