Item ST 15459 Multiple Tuner - Marconi, Radio Receiver, circa 1908

Summary

Multiple radio tuner, made by Marconi's Wireless Telegraph Company, England, circa 1908. Used with spark receivers on both land and sea. The tuner was connected between the aerial and the detector in order to select the receiving frequency. This type of technology was superseded during World war I (1914 - 1918).

This equipment is the same model as that used on the radio system on the Titanic ship at the time of the disaster in 1912.

Three controls on the top adjust the tuning of the aerial, detector and intermediate tuned circuits; the controls are variable capacitors. On the front, the left hand control adjusts the aerial tuning inductance and the right hand control perates three ganged switches, which set the tuning range of the three controls on top. The knife switch on the top selects between standby and tuned modes.

The item on the left hand front corner is the micrometer spark gap. This was provided to bypass the radio frequency energy coming from the transmitter when the key was pressed. There was no mechanical transmit/receive switching apart from the back contact of the key which would short the headphones when the key was pressed. This allowed 'break-in' operation where the operator would be able to hear another station trying to break in during the sending of a message.

Physical Description

Wooden box with composition front panel and top. The top holds three large brass and composition controls, four terminals, one knife switch and a brass housing. The front panel holds one rotary switch and a three ganged switch. On one end is a rotary control.

Significance

The equipment is typical of early shipboard radio in the period prior to the First World War (1914 - 1918); it is rare.