Welcome back to the second stage in the tour. Most of this page is devoted to small Private Automatic eXchanges (PAX's), i.e. local
exchanges which usually had no connection to the public network. However, first a couple of unusual public system items. The unit on the right is a trunk line amplifier or "repeater". Repeaters were situated at intervals along the long trunk cables between cities. They were usually housed in dedicated buildings although in cities they were often in the same building as an exchange. Earlier repeater stations used valve amplifiers but the stations only needed to be around 15 miles apart. However, later buildings housed smaller equipment but were usually then required at more frequent intervals, such as every three miles. The STC amplifier shown here is of 1930's design.
Another interesting rarity is this fuse panel from a VF Telegraph station. Voice Frequency telegraphs operated teleprinter networks over long distances and this wartime panel is from a derelict military radio station. I donated my VFT amplifier rack to Bletchley Park so I cannot show that to you.
ATM 25 line pre-2000 PAX on the work bench, circa 1933. The rear gate is swung around to show the selectors. Rescued from an electricity board museum, believed to have been used in a sub station in Staines.
GEC 50 line uniselector PAX, circa 1947
ETL/Plessey 10 line uniselector
PAX. This is a real miniature Strowger exchange, based on one uniselector and built into a small box no bigger than a shoe box. Circa 1966
ATE/Plessey 15 line uniselector
PAX. Fitted with tie line.
ATE/Plessey 25 line 2 motion selector
PAX. Contains 4 x 2 motion switches, one of the smallest 2 motion PAX's of recent years. Rescued from a Scottish distillery.
On the left is an STC 25 line uniselector
PAX of 1961, also rescued from an electricity power station where it was used to extend a large GEC
PAX of several hundred lines. On the right is a GEC SE50 50 line PAX of 1959, using type 4000 selectors.
In the centre is a T&N 27 line PAX incorporating a small ringing machine, circa 1966. On the right is a 20 line DeTeWe
PAX using diode signalling, i.e. push button phones with diodes working in combination with the 3rd earth return leg. Circa 1967. The small PAX on the left is a Siemens all-relay PAX circa 1931. As this is one of the oldest PAX's I know, and it does need some attention, I would be grateful to hear from anyone who may have any technical knowledge of its operation, or in particular, any technical wiring drawings etc. There are some closer pictures here, of the outside, also the outside label and of the inside. 
This is a small German 16 line PAX manufactured by DeTeWe.That concludes the short tour. I have not been able to show everything but I have tried to give an idea of the scope of my collection. Visitors are welcome, but please send me an email in the first instance to arrange an appointment.
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