Bunnell Double Speed Key and Vibroplex Key

The Radio Sideswiper by Bunnell 1923-1925
The Radio Sideswiper by Bunnell 1923-1925


7A      The Double Speed key is of the type known a "sideswiper." Unlike the straight keys shown on page6, this key is worked by alternating side-to-side movements. Since the left and right contacts are electrically (and mechanically) connected, dots or dashes may be made in either direction. Usually, the code elements were made by working the lever alternately to the left and right irrespective of whether a dot or dash was to be made.

      The reason for the sideswiper was to avoid the vertical motion of the straight key which was thought to cause the "telegrapher's paralysis" (carpal tunnel syndrome) that afflicted may operators.

7B      The mechanical semiautomatic telegraph key was invented in 1904 by Horace Martin. He called it a "Vivbroplex," although it was often called a "bug" by operators derogating those who used it.

      Like a sideswiper, it is worked by a side-to-side motion. However, while the knob must be pressed to the left for each dash, dots are made automatically by a vibrating pendulum when the paddle is pressed to the right. Its appearance here shows that the Bunnell marketed products other than its own.

      The No. 4 model Vibroplex appeared in 1914 with an attractive blue japan finished base. The model was later call the Blue Racer. It wasn't quite as small as the description might lead you to believe: it measured 2.5 inches wide by over 6 inches long.

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