TELEPHONE No. SA 5031 | |||||||
| Modified 300 type table telephone, used with Privacy
Sets No. 6 and No. 7 on L.B. (C.B.S. 1, 2 & 3) and Magneto systems. The Privacy sets were speech scramblers and
afforded secure communication to a distant privacy set. Privacy sets
are also known as Frequency Changers.
These telephones were generally built up, when required, using a Telephone No. 394 Black, Telephone No. 164 Green, Key No. 303A and an 8 way line cord. The green handset was to allow easy identification of the secure phone. Factory assembled SA 5031 instrument are extremely rare as most of them were built by engineers in the field from locally available components and therefore most telephones are marked Tele No. 394 on their base and chassis. The telephone had provision for three press button keys. Normally the middle button would be left blank and only used if recall facilities or a ring button were required. The left button was originally labelled "Secret", which later changed to "Scramble" and the right button labelled "Normal". The newly introduced Receiver Inset No. 2P was also specified for these telephones as the reception quality was considerably better than the Receiver Inset No 1L. The Receiver Inset No. 2P also used the newly introduced Earpiece No. 23 and due to war time shortages black earpieces were used when green was not available. When green handsets were not available the GPO Factory would paint the handsets a Lime Green colour. Factory modified sets would have been marked SA 5031 but those built in the field would have retained the original Telephone No. 394 (or 396 if the 394 not available) markings on the base and chassis. Visit the Crypto Museum for more information Introduced in August 1940. Circuit diagrams - SA 5031 and SA 5065.
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Last revised: May 11, 2023FM |
