Junker Telegraph Key


From 1926, the former naval captain Joseph Junker created the telegraph key ("Junker-Taste"). It was patented in 1931 and subsequently manufactured by the MT company Joseph Junker founded, and the key wasn't changed to this day. These keys features the adjustable spring pressure of the transducer arm and the adjustable distance between the switch contacts ("Hub") of the key button.

The patent of 1935 argues the need to adapt to the different hand weights of radio operators without interruption of radio operation. This allows "on-the-fly" changes by the radio operator on the same key in order to ensure a continuous operation without fatigue. Markings on the screws could be individually adjusted and quickly be restored.
This key is equipped with a protective circuit (LCR circuit). This protection prevents inductively loaded current to flow creating a switching arc from telegraph signals on key contact. This switching arc would damage the surface of the contacts (contact wear).






















The left photo shows the "Entstört" label, which means filtered or interference suppression. There is a low-pass filter built into this key to remove higher frequencies. Here is the schematic borrowed from Radiomusem.org. The right photo shows the "D.R.P. Junker" label, which is "Deutches Reichspatent".