5 Kw "Plain Discharger " Set
Three different 5 KW transmitters aee described in the Handbook of Technical Instruction for Wireless Telegraphists. They are called the "Plain Discharger Set" , the "Battleship Set" , and the "Special Set".   The Plain Discharger set used an ordinary spark gap mounted in a box  It was called by that name to distinguish it from rotary gap sets.

The Battleship Set used a synchronous rotary gap in a heavy teak box. Radio operators said that the Titanic was the first ship to receive a synchronous gap transmitter.  It was the only ship that produced a musical note. The rotary gap for the Special Set was encased in a round aluminum case.

A  detailed article on the radio equipment on the Titanic is availanle in the Vol. 25, 2012 issue of the Antique Wireless Association Review.

Plain Discharger Power output: 5,000 watts
Frequency range: 300 or 600 meters. If a similar jigger  to the one used in the 1/.5 kw shipboard transmitter was used, then the frequency range was 200 to 1100 metres.  A jigger (see note 1)  was a term commonly used in the late 19th century/early 20th century, to refer to a high-frequency transformer used in early spark transmitters to couple the aerial circuit to the oscillation-generating circuit. In modern terms, a type of transformer.

5kw_discharger_set_s.jpg This image describes the principal parts of the 5 kw Marconi "Discharger  Set" . Click on thumbnail to enlarge.   (Image courtesy Handbook of Technical Instruction for Wireless Telegraphists). 
5kw_discharger_spark_gap_s.jpg This image describes the principal parts of the 5 kw Marconi "Discharger  Set" spark gap. Click on thumbnail to enlarge.   ( Image courtesy This image describes the principal parts of the 5 kw Marconi "Discharger  Set" . Click on thumbnail to enlarge.   ( Image courtesy Handbook of Technical Instruction for Wireless Telegraphists). 
Note 1: The use of the term " Jigger" in wireless, first appears in Marconi`s  7777 patent on tuning in 1904. In the vast amount of radio literature that is out there,  the term can be found in only two places.  It is found in textbooks only when they are referring to the 7777 patent.   It is also found in the Handbook Of Technical Instruction For Wireless Telegraphists,  by J.C. Hawkhead & H.M. Dowsett  only when they are referring to products that were manufactured by Marconi. The use of the term could not at any time have been popular or common. A good reason for it being unpopular was that Marconi`s claim to be the inventor of tuning was widely disputed and was not settled until 1943 when the USA Supreme Court ruled in favor of Tesla


Contributors and Credits:

1) Lewis Bodkin  <05bodkin555(at)gmail.com>
2)  Handbook of Technical Instruction for Wireless Telegraphists).

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