TC 61

Telecrypto 61, TC 61; manufactured by Dr. Edgar Gretener AG, Zurich.

Dr. E. Gretener AG, Zurich, which had already developed the single-tone combination teleprinter ETK and the Telekrypto 53, which could encrypt the 14-character signal of the ETK teletypewriter, developed a set based on a similar encryption technology, the Telekrypto 61, to work with teleprinters using the 5-step Baudot code CCITT No. 2.

Technical data

Principle: Cipher machine
Operation modes: based on the Vernam principle with integrated key generator

Power supply

Mains operation: 220 V AC mains

Dimensions

Upper part (encryption unit): 610 x 340 x 340 mm; 33 kg
Lower part: 680 x 340 x 340 mm; 70 kg

Accessories

Operation

The TC-61 telecrypto ciphering machine consists of a base unit with the control elements for synchronising the teleprinters and the classified attachable cipher section with the actual cipher mechanism and a mechanical key production unit, which was used to generate random-based cipher keys.

The cipher unit is mounted on the lower unit and connected mechanically. On the left-hand side of the Swiss army variant is the round black key production unit, this is used to generate a common encryption key by both sides based on the daily key and a sequence of 12 numbers transmitted open to the remote station.

At the right of it, you find the display windows of the four wired cipher wheels and further right, eight more polarity reversal cipher wheels. The black step switches are used to set the cipher wheels to the start position for decoding; the red switches are used to select additional polarity reversal steps.

The electronics for synchronising the cipher machines are located in the lower section; the yellow changeover switch switches from clear to cipher mode.

Technical principle

Tube configuration

* The set is equipped with 13 E90CC, two GR15 and one EM84.

Development

Deployment

The TC-61 telecrypto ciphering machine was usually used together with a Stg-100 teleprinter or Stg-68 tape teletypewriter - i.e. sets using the 5 bit Baudot code and not the 14-segment code of the ETK teleprinter.