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1948 Semiautomatic Eddystone S689 Bug Key EZ0936

1948 Semiautomatic Eddystone S689 Bug Key EZ0936


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1948 Semiautomatic Eddystone S689 Bug Key EZ0936

This amazing looking Morse key is a 1948 Semiautomatic Eddystone S689 Bug Key EZ0936.

The Eddystone S689 Bug Key holds a unique position. It is, with the exception of the 'Autopiler' of 1932, the only Morse key of semi-automatic design manufactured and sold in Great Britain in limited numbers. A piece of communication history!

This Key is in original condition and has not been repainted. The top cover bears a few paint chip 'battle scars'. It comes with the original lead and jack plug.

  • Maximum Length:- 21.5 cm (nose to end of the key)
  • Maximum width:- 9cm

The top of the key is marked Eddystone, and the underneath has 'Model S689,' 'Ro. No.853967' and EZ0936.

The exact number of S689s produced is unknown, but it seems clear that the figure did not exceed 500 and today we have one of them on offer.

Design and Construction

  • The key is almost entirely constructed of untreated brass and die cast aluminium, with the base and cover being finished in black crackle enamel and it weighs in at 1.4 kg. 
  • Adjustment followed the convention of other conventional single lever semi-automatic keys with the exception of the dot return coil spring, the tension of which is not independently adjustable. 
  • This spring is held by the left-hand control arm stop screw and the tension can only be varied to a small degree by setting of both the left-hand and the right-hand stop screws. 
  • The main pivot pin bearings consist of a single ball for each bearing, only the lower of which is adjustable. 
  • Two speed weights are provided, one large and one small, and use of either or both can give a wide variation in dot speed. 
  • The arm is damped in the rest position by a rubber grommet on the back stop. 
A testimony to the quality of design and production engineering standards of Eddystone is that, unlike the majority of other designs, the control arm of the S689 can be completely dismantled down to individual components.


By the late 1940's, the Birmingham based Stratton and Company Ltd, later to become known as Eddystone Radio, had built up a fine reputation for the manufacture of high class communication receivers and accessories but it was not until late 1947 that work began to develop a semi-automatic Morse key in the style of Martin's 1904 Vibroplex Original design, but in a style in keeping with the traditional Eddystone use of die castings.

Following a showing of pre-production devices at the Amateur Radio Exhibition in November 1947 an initial production run of 250 keys was made in early 1948. Although the S689 was liked by many users, sales of the key continued to be poor and at the prospect of continuing poor sales, Eddystone 'pulled the plug' offered the remaining unsold but assembled keys, and the entire stock of unassembled components, as a clearance lot to Birmingham's Chas. H. Young Amateur Radio Company, who placed the S689 on special offer and continued selling them until stocks were exhausted.

Please click on the following link for more vintage morse keys.

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