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Spendex 30/35 (UA-8237)
Secure phone - Wanted item

Spendex 30 was a low-cost narrow-band voice crypto device, developed by Philips Usfa in Eindhoven (Netherlands) between 1974 and 1982. It was based on a Formant Vocoder, developed by Philips Research (Nat Lab). The device was never taken into production, although a small quantity was built by Philips-daughter MBLE in Belgium for use by the Belgian Police (Rijkswacht).

The image on the right shows a prototype of a Spendex-30 unit. It consists of a small metal case with all controls at the front. Als at the front is a standard telephone handset, that is connected to the unit by means of a DIN-plug.

At the initiative of Philips Usfa, Philips Research (Nat Lab) developed the narrow-band vocoder based on the formants present in human speech. After the first functional prototype, the device was redeveloped a number of times, but the results with respect to the speech quality were disappointing [3]. The price was low however.
Spendex-30 prototype

The cryptographic strength of the Spendex-30 was good enough for military and governmental applications. For civil use, the Spendex-35 variant was available. Development of the device was postponed several times due to problems with MUCOLEX which was developed at the same time. By the time the device was finished, its design had already become obsolete as better vocoders had become available, such as the LPC-10 coding used with the military Spendex 40 phone.

A small quantity of civil Spendex-35 units was built by Philips-daughter MBLE in Belgium for use by the Belgian Police (Rijkswacht). Although MBLE built the units, the crypto-heart was supplied by Philips Usfa. The exact number of units is unknown, but Philips Usfa built 45 PCB sets for it [3]. Below are some more images of Spendex-30 prototypes.

  1. AIVD website, Photograph of Spendex 30

  2. Philips Usfa/Crypto, Spendex 30 stock photographs
    Crypto Museum Photo Archive.

  3. Philips Usfa, Internal Memo L/5636/AvdP/JG
    23 August 1982, page 5.

  4. Philips Usfa BV, Spendex 30, Narrow-band Secure Voice Equipment
    Copy of 4-page brochure. Date unknown, but likely early 1980s.
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