Modified 300 type table telephone, used with Privacy Sets No. 6 on L.B. (C.B.S. 2&3) and Magneto systems (plus long lines on CB/Auto systems).  The Privacy sets were speech scramblers and afforded secure communication to a distant privacy set.  Privacy sets are also known as Frequency Changers.

Telephones SA 5063/0 were generally built in the GPO factory but some were still locally made up when required, using a Telephone No. 394 Black, Telephone No. 164 Green, Key No. 303A, Block Terminal No. 6 and a 12 way line cord.  The green handset was a to allow easy identification of the secure phone.

The Telephone SA 5063/1 could be used either on a direct exchange/PBX line or with a Unit, Auxiliary Apparatus SA5050 to allow up to three sets of multiple SA 5063/1 instruments wired in parallel to access a single Privacy set.  The main difference between the SA 5063/0 and the SA5063/1 is that the latter had additional security switch contacts so that other instruments wired in parallel could not eavesdrop on a scrambled conversation.  Diagram SA 5065 refers.

Telephones SA 5063/1 were all made from the Telephone No. 394.  The GPO factories modified the chassis wiring harness by partially hard wiring the Key No. 303B.

The telephones 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" and the right button labelled "Engage for Secret".  This changed later on, the left button labelled "Scramble" and the right button labelled "Hold Scrambler".  If installed on a Direct Exchange line the "Engage for Secret" button was not used.

Telephone SA 5603/1 could be used on Plan 1A installations whilst the Telephone SA 5063/0 could not.

Telephone SA 5063/1 could be used on the three sharing scheme in conjunction with a Unit, Auxiliary Apparatus SA 5030 and three Indicators No. 401CN.  This allowed three telephones to use one Privacy Set and also to hold the privacy set for a forth coming secure call, thus preventing the other two users from making secure calls.

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.

Many of these phones have been found to be semi-tropicalised.  Whilst there is no mesh over the sounds exit holes, the capacitor is marked tropical finish and some of the metal work and screw terminals have been varnished.

Factory modified sets would have been marked SA 5063/0 or SA 5063/1 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.

Telephone SA 5063/0 was introduced in 1943.
Telephone SA 5063/1 was introduced in February 1944.

Circuit diagrams - SA 5063, SA 5063/0, SA 5063/1 and SA 5065.

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Installation Instructions
Telephone SA 5063/1

Telephone SA 5063/1 comprises of the following:-
1 x Telephone No.396 C.B. Black minus cord and handset.
1 x Telephone No.164 Green fitted with a Receiver, Inset No. 2P and an Earpiece No. 23 Green.
2 x Parts No. 1/SPL/325.
1 x Key No. 303B.
1 x Label No. 252R.
1 x Cords, Instrument No. 12/03G Brown 54".
1 x Block Terminal No. 6.

Key No. 303B is fitted with control plate in position 6.  Plungers A & C are fitted and the extension arm is fitted to give gravity switch hook to normal (see N4301).

Additional Pictures








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Last revised: August 24, 2023