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Portable Data Terminal - wanted item

DDT-300 was a portable message terminal with built-in encryption and decryption facilities, developed in the mid-1970s by Tele Security Timmann (TST) in Rodgau (Germany). It features a built-in acoustic telephone modem and was compatible with the tiny APT-60 pocket terminal [1].

The image on the right shows a typical DDT-300 terminal that is housed in a strong aluminium Haliburton briefcase of the 1970s. The device consists of three parts: a full Latin keyboard with the German QWERTZ layout – used for input – in the blue area at the front, a single-line red LED diplay – for output – in the grey area behind the keyboard, and an acoustic modem at the right.

The acoustic modem consists of two adjustable black rubber funnels into which the handset of a regular analogue telephone set can be placed. This way, the device's internal modem can send and receive standard audio tones according to the BELL 103 standard, allowing digital data to be exchanged at a speed of 300 baud. A built-in cipher unit allows the messages to be encrypted using a proprietary TST encryption algorithm, developed by company owner Timmann himself.

The DDT-300 was fully compatible with the earlier APT-60 miniature pocket terminal and was capable of deciphering messages received from an APT-60 device. It was not possible to send messages back to an APT-60, as the APT-60 did not have receiving capabilities. It was possible however, to exchange messages (i.e. send and receive) with another DDT-300 data terminal.

The DDT-300 was eventually replaced in the early 1980s by the compatible TST-3300. Encryption and decryption are based on the same scheme as the later TST-2305 and TST-3336 terminals. The image above shows the DDT-300 in an opened briefcase, alongside the Latin (center) and Arabic (right) versions of the APT-60 device, with the Arabic version concealed in a leather case.

  1. Helmut 'Jim' Meyer, HS0ZHK, My way to Ham - Radio and beyond
    Website QRZ.COM. Personal correspondence. Retrieved March 2018.
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Crypto Museum. Created: Monday 04 March 2013. Last changed: Sunday, 04 March 2018 - 14:01 CET.
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