The Lytle Triplex Semi-Automatic Telegraph Key
Lytle Triplex Key in Right-Hand Position
Right-Handed Position
This rare "Lytle Triplex" telegraph key was made by the Precision Thermometer & Instrument company of Philadelphia.  Walter Lytle applied for a patent on this device on June 21, 1921.  The patent was issued on Feb. 12, 1924 (no. 1,483,669), so the key shown here was made sometime after that date.

It is a semi-automatic key, similar in operation to the Vibroplex, but it has a unique feature that sets it apart from all other keys.  

The standard Vibroplex configuration of the knob and paddle was optimum for the right-handed operator.  A movement of the lever to the right produced dots, and to the left it produced dashes.  A lefty had the option of special ordering a left-handed key, with all parts and functions reversed.

The Lytle Triplex allowed operation as a semi-automatic key for either the right or left-handed operator, and it could also function as a standard "straight" key (up and down lever motion).  To change the mode of operation, a spring-loaded locking pin is pulled out, and the lever assembly is then free to rotate.

Most of the pieces are lacquered brass, and the base is a solid block of brass.  I am told this key originally came in a little metal carrying case that was shaped like a mailbox.

Lytle Triplex Key in Left-HandPosition
Left-Handed Position
Lytle Triplex Key in Straight Key Position
Straight Key Position
Lytle Triplex Nameplate