TXE3
TXE3 was a cost reduced and improved version of TXE1 designed for exchanges with more than 2000 subscribers and was very similar in design to the later TXE4. The same three companies that built the TXE1 developed TXE3, namely STC, AEI and AT&E and it was intended to be the standard BPO system for large exchanges. The prototype exchange was built and tested in the Circuit Laboratory at Armour House. The trial period was for 200 subs, 100 were for senior engineers within Telecoms HQ the remaining 100 subs were transferred from Monarch exchange, in the City of London, on a temporary basis (via c/o switches in case something went wrong). The trial lasted from 1969 until 1970.
During the development of the TXE3 it became apparent that the system would be too expensive for the competitive export market, so AEI split its team into two: one to do whatever the BPO wanted and the other to produce a reduced version for export. The trial was started in April 1968 and the model worked very well at Armour House and the BPO ordered the first half dozen exchanges. Jim Warman moved his team back from Blackheath to Woolwich to start a new department with its own manufacturing and marketing. The equipment for the first exchange had been manufactured with a 9600 capacity and was being installed on site at Royal exchange in London in 1968 when GEC made a takeover bid for AEI who were in financial difficulties brought about by the development costs of TXE1 and TXE3. The takeover bid was and GEC decided, unbelievably, that they preferred the crossbar system to TXE3 and promptly cancelled the contract to supply TXE3 to the BPO. Royal first exchange was dismantled before its installation had been completed and all the TXE3 equipment was broken up and supplied to universities for observation.
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