Homepage
Crypto
Index
Glossary
Enigma
Hagelin
Fialka
Nema
Voice
Hand
OTP
EMU
Mixers
Phones
FILL
Codebooks
Algorithms
USA
USSR
UK
Yugoslavia
Ascom
AT&T
Bosch
Datotek
Gretag
HELL
ITT
Motorola
Mils
OMI
Philips
Racal
Siemens
STK
Tadiran
Telsy
Teltron
Transvertex
TST
Spy radio
Burst encoders
Intercept
Covert
Radio
PC
Telex
People
Agencies
Manufacturers
• • • Donate • • •
Kits
Shop
News
Events
Wanted
Contact
About
Links
   Click for homepage
TST-7595
Voice scrambler for HF radio

The TST-7595 was a small military-grade voice encryption unit, developed by Tele Security Timmann (TST) in Pöcking (Germany) around 1985. It was intended for use in combination with military HF transceivers and was so small that it could be fitted to the side of such a radio set.

The image on the right shows a typical 7595, which is housed in an extruded aluminium casing, similar to the ones used for other TST devices, such as the TST-3010 message unit.

The device is shown here with a modern German handset that is connected to the NF10 socket at the right of the front panel. The socket at the left is used for connecting the TST-7595 to the transceiver, which should also provide the necessary power. The cryptographic key is entered into the device by using the rotary dial (0-9) in combination with the push-button.
  
TST-7595 voice encryptor

The TST-7595 was sold world-wide and was rather popular with foreign armies. In the UK, the device was sold by Marconi, who used it in combination with their Clansman radio sets. Although the nearby German Army Signals School in Feldafing helped testing the usability of the TST-7595 in the field, Timmann, to his dismay, was not allowed to supply the devices to the German Army.

Please note that the TST-7595 is not a digital encryption device, but rather an analogue one, that was built with the latest digital techniques of the era. It was intended for use in situations where digital encryption was not possible or practible, such as in combination with analogue narrow-band HF radio sets. It offered good voice quality and did not reduce the operational range of the radio. As long as clear voice was possible, the TST-7595 would scramble it, using three different techniques: Frequency Domain, Time Domain and Inverted Time Domain scrambling [2].

TST-7595 voice encryptor TST-7595 with handset Front panel of the TST-7595 Dialing a digit (0-9) Entering a digit NF10 socket for handset Socket for connection to the transceiver and power source Operating the PTT

Controls
From the outside, the TST-7595 is a rather simple device, with only a few controls and connections. The larger socket is used for connection to a transceiver, such as the British Clansman series, whilst the smaller one is used for connection of a handset with PTT.

Front panel of the TST-7595. Click for a larger view.

The rotary dial at the center is used in combination with the LED indicator and the Push-To-Talk switch on the handset (PTT), for entering the cryptographic key into the device. In normal use, i.e. when operating the device, the rotary is used to select one of the previously stored keys.

Interior
The TST-7595 is housed in a strong aluminium enlosure that consists of an extruded aluminium shell with die-cast aluminium panels at both ends. These side panels are inserted into the case and are each held in place by four tiny hex bolts in the corners of the outer shell.

Removing the hex bolts in the corners is easy, but removing the side panels is more difficult as the bolts have caused the aluminium to deform somewhat. With proportional force and the right tools however, it should be possible to remove them without causing damage to the front panel.

After removing the control panel, the interior of the TST-7595 becomes visible. Inside the case are two PCBs that are held in place by rigs in the sides of the outer shell. After carefully removing the front panel connectors from the PCBs, the two PCBs can be extracted from the case.
  
Close-up of the DAC

The two PCBs are slightly longer than standard Eurocard format (10 x 16 cm). One board is the analogue processing card, marked TST 7595 APC, whilst the other one does holds the digital components. It is marked TST 7595 DPC and has a cut-out that accomodates the front panel. The internal power supply is located in the side panel opposite to the side of the front panel.

Hex bolts in the corners of the outer shell Front panel detached from the PCBs Power supply mounted in the other side panel Both PCBs Digital board Analogue board Close-up of the flat-cable connectors on the digital board Close-up of the DAC

Specifications
  • Size: 4 x 10 x 25 cm
  • Weight: 1 kg
  • Power: +9 to +15V DC (+8 to +33V by special order)
  • Consumption: < 1W
  • Power supply: via transceiver
  • Storage temperature: -20°C to +70C
  • Operating temperature: -10°C to +60C
  • Shock and vibration: C/514.2-3 B
Accessories
  • TST-0606 Random Generator (for creating random keys)
  • TST-0810 Key management System
References
  1. Helmut 'Jim' Meyer, HS0ZHK, My way to Ham - Radio and beyond
    Website QRZ.COM. Personal correspondence. Retrieved July 2013.

  2. TST Timmann, TST-7595 Sprachverschlüsselungsgerät für HF-Funkgeräte
    Sales datasheet, 3 pages (German). 18 April 2007. Retrieved July 2013 from [1]
Further information
Any links shown in red are currently unavailable. If you like the information on this website, why not make a donation?
Crypto Museum. Last changed: Sunday, 08 March 2015 - 09:08 CET.
Click for homepage