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TST 9669
Baudot and ASCII encryptor - wanted item

The TST-9669 was a universal encryption/decryption system for telex signals (Baudot) and computer data (ASCII), developed and produced by Tele Security Timmann (TST) in Tützing (Germany) around 1982/83. It was suitable for a wide variety of security solutions. The unit was available in a green metal enclosure, but also as a single crypto-board for OEM applications.

The image on the right shows a typical unit in a rugged green aluminium enclosure, which is similar to the earlier TST-4043. It is powered directly from the 220V mains and all wiring is at the front. It is suitable for off-line and on-line use, and is operated via the connected terminal (computer or telex). The device is suitable for Latin-based languages as well as Arabic.

Cryptographic keys are loaded by means of the dedicated TST-0706 (with TST-0502 key card), or manually via the connected terminal.
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The TST-9669 and the OEM version of the 9669 board, were very successfull and greatly boosted sales throughout the 80s. They were first shown to the public on the Military Electronics Defence Expo (MEDE) in 1983 and became an instant world-wide success.

OEM versions
The TST-9669 was so universal that it was used as the heart of other TST cipher machines, but also as part of cipher machines made by other manufacturers, to which it was available as a third-part OEM product. Below are several examples of the use of this Eurocard-size PCB.

Siemens T-1000
One of the first applications of the board was inside the Siemens T-1000 teleprinter.

Due to its small size, the 9669 board could be installed instead of the line interface, rather than mounting it to the bottom of the T-1000 as some other manufactuers did. All configuration and key loading was done via the keyboard of the T-1000 through the built-in user interface.

The T-1000 with TST-9669 crypto board was a direct competitor of the Philips Aroflex and the Hagelin HC-550/580.

 More about Aroflex
 More about the HC-550

OEM version of TST-9669 inside a Siemens T-1000 teleprinter

TST-3550 Mark II
The OEM-version of the 9669 was later also used in the TST-3550 Mark II, where the basic 9669 board was mounted in a separate shell that was bolted to the bottom of the TRS-80 Model 102 host computer.

In the early 1990s, the TRS-80 replaced the original TI Silent 700 computer.

 More information

Flight case with TST 3550, printer and acoustic coupler

The TST-9669 board was also used as the heart of the earlier TST-4043 data encryptor, shown in the image on the right.

 More information

TST-4043 front panel

The TST-9667 [3] is a variant of the TST-9669, which has similar specifications, but different connectors. It connects directly to a PC, a telex machine and a radio, but requires an external modem for connecting it to a telephone line.

This was done to circumvent the time-consuming approval procedures in certain countries. By using an (already approved) external modem, no explicit approval was needed for the TST-9667.

The image on the right shows a typical 9669 OEM board. At the left of the PCB are the typical 25-way D-type connector and the 4 LEDs. The board is built around a military-grade NSC 8000 microprocessor (Z-80 compatible) with external RAM and an EPROM containing the firmware.

The cryptographic keys are retained in battery-backed static RAM that can be wiped instantly when security is compromised. In order to protect the design, the text was removed from some of the ICs, as can be seen in the image above. This was common practice in the early 1980s. In the early 1990s, the NSC 8000 microprocessor was replaced by the much cheaper Zilog Z-80.
Main crypto card

Forward Error Correction (FEC)
At the right side of the board is an expansion connector that allows a small daughter card to be mounted on top. For customers who wanted to use the encryptor for online applications, it was possible to add a versatile modem with built-in Forward Error Correction (FEC).

The image on the right shows the optional TST-082 daughter card that could be mounted on top of the OEM version of the 9669. It has a fully equipped 300 baud HF-modem with FEC. The card shown here was a smaller replacement for the earlier design, and has a dedicated FEC chip.
Daughter card, component side.

  1. Helmut 'Jim' Meyer, HS0ZHK, My way to Ham - Radio and beyond
    Website QRZ.COM. Personal correspondence. Crypto Museum, July 2013.

  2. TST-9669, Verschlüsselungsgerät für Baudot und ASCII-Daten
    Tele Security Timmann (TST). Sales brochure, 7 pages. Date unknown. 1

  3. TST-9667, PC-Controlled Encryption System for Baudot and ASCII Data
    Tele Security Timmann (TST). Sales brochure, 7 pages. Date unknown. 1
  1. Brochure kindly supplied by Helmuth (Jim) Meyer [1].

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Crypto Museum. Created: Sunday 11 August 2013. Last changed: Friday, 23 December 2022 - 08:41 CET.
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