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TST-4045 →
Digital voice encryptor

TST-7698 was a digital voice encryption and decryption unit, developed in the mid to late 1980s by Tele Security Timmann (TST) in Tutzing (Germany). It was intended for use in combination with SW/HF, VHF and UHF radios and used a Linear Predictive Coding (LPC-10) vocoder as digitizer.

The device uses a digital vocoder (digitizer) that offers excellent speech quality, even at a bitrate of 2400 baud. It is suitable for voice encryption via noisy shortwave (SW) radio channels, and is commonly used with the SSB mode of the radio. When connected to a VHF/UHF FM radio, higher baudrates of up to 9600 baud are possible [A].

The device has 9 compartments for the storage of cryptographic KEYs, that are loaded into the device with a TST-0706 reader and a TST-0502 key card. The key loader should be connected to the same socket as the radio (the leftmost NF-7).

The TST-7698 was introduced in the mid or late 1980s, as the successor to the TST-7595 SW/HF voice scrambler. Although both devices look very similar — they are housed in the same rugged enclosure and have identical controls and connections — the TST-7698 is much more secure as it offers true digital encryption. The TST-7698 was also used as part of the TST-4045 HF modem.

  • TST 7698-2
    Suitable for VHF/UHF, 2400—9600 baud
  • TST 7698-3
    Suitable for VHF/UHF and HF, 2400 baud
  • TST 7698-6
    Same as TST 7698-2, but wit 2dB higher output level
  • TST 0606
    Random generator for creating keys
  • TST 0810
    Key management system
  • TST 0706
    Key reader/loader for key cards TST 0502
  • TST 0708
    Reader/writer for key cards TST 0502
  • TST 0502
    Key cards for transferring cryptographic keys
  1. TST 7698 sales brochure 1
    Date unknown. 6 Pages (German).

  2. TST 7698 handbook 1
    8.20 F. TST, 1988. 38 Pages (English).
  1. Kindly supplied by Jim Meyer [1].

  1. Helmut 'Jim' Meyer, HS0ZHK, My way to Ham - Radio and beyond
    Website QRZ.COM. Personal correspondence. Retrieved February 2018.
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