TXE2
The prototype for the exchange which the GPO called TXE2 was a system called Pentex (the Plessey trademark for all non-GPO sales), which, starting in 1963, was developed by Ericsson Telephones, as part of Plessey. The first field trial of Pentex started in the Peterborough Telephone Area in 1965. There was another trial site at Leamington. The system was designed to serve 200 - 1200 customers and about 240 Erlang units. It was therefore mainly used to replace the larger rural Strowger exchanges - usually UAX13s. The first TXE2 was installed at Ambergate near Matlock in Derbyshire and it opened on 15 December 1966. Ambergate was chosen because it was a suitable small exchange (200 lines) which was some 20 miles from the Plessey factory at Beeston, Nottingham. The manual exchange which it replaced was kept on standby for several months, until sufficient operational confidence was developed in the TXE2. Although the system had been developed by Plessey, for security (and perhaps in an attempt to drive prices down) the GPO had insisted on competitive tendering for the TXE2 exchanges. Production contracts were awarded simultaneously to Plessey, STC and GEC, and the distribution of the three manufacturers products into the field was done on an apparently random basis. Some 2-3000 TXE2s went into service with the GPO, the last one being withdrawn from service on June 23, 1995.
The Pentex system, which evolved beyond TXE2, was exported to over 30 countries and was largely responsible for Plessey winning the Queen's Award for Exports in 1978.
In the summer of 2005 a demonstration rack of TXE2 equipment was transferred to the Connected Earth collection at Milton Keynes Museum. See
There is a working TXE2 at Avoncroft Museum. It can be used to make calls within the museum. For more information about this Plessey mobile TXE2 (or MXE2, as they were called) at Avoncroft Museum see
A few details about the MXE2s are given at
Many of the MXE2s ended up in Northern Ireland. Only one of these ever had to be used 'in anger'. This was at Castlewellan about 1990, when the exchange was blown up by terrorists. The typical set-up time for an MXE2 was about 6 weeks, but at Castlewellan full telephone service was restored using an MXE2 (and the additional use of a mobile transmission unit designed by Northern Ireland staff) within one week of the bombing. It did however take a lot of subsequent work by the switch maintenance Technical Officers to get the exchange up to an acceptable standard of service, as it had been standing idle for several years.
The photograph on the right (and slightly below this paragraph) shows several racks inside Ambergate Exchange. Although the first TXE2-type exchange to go into public service, it actually consisted of Plessy pre-production equipment, called Pentex. The clumsy large handles on the front of the slide-in units are the obvious distinguishing feature. It is also apparent that the racks and units are painted in battleship grey. The change from this to the 'light straw' colour of all subsequent exchanges was a significant change in an organisation where exchange equipment had been battleship grey for as long as any telephone engineer could remember.
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