The prototype CH system...
During the latter part of the summer of 1935 confidence amongst
the scientists and engineers was growing that a system of major
national importance was emerging. By October, Watson Watt had clarified
the proposal that a series of transmitters and pairs of related
receiver stations should be constructed all along the east and south
coasts of Britain. It would be necessary to position the receivers
some 10 miles away from each transmitter because they were easily
'swamped' with signals from the transmitter if they were positioned
any closer. As a first step, a demonstration station needed to be
Also, as the success and size of the team grew and so did their
need for more space and facilities. The Air Ministry commandeered
Bawdsey Manor, just ten miles away, in February 1936. Thus it was
that Bawdsey Research Station came into existence a month later.
One of their first technical tasks was to solve this problem of
'receiver saturation' (the overwhelming of a receiver signal by
the high power of the transmitter signal) and it was duly resolved
during the spring. When the preliminary sites became operational,
it was practical to have both units based at the same site. The
first operational 'CH' station was understandably installed at Bawdsey
with all haste. A further 5 prototypes to cover the Thames Estuary
were ordered and were to be constructed by August 1936.
Much of the research into high power transmitter
valves had been carried out in the valve laboratories
of Metropolitan Vickers under the leadership of
Dr Dodds and so it was logical thatthey should
obtain the contract to supply the new transmitters.
Some of the insulation parts were actually manufactured
in Germany !
It has often been noted that the very close cooperation
between the Government researchers and the manufacturing
companies such as EMI, GEC and Vickers might explain
how this new technology was brought to fruition
so successfully and in such a short space of time.By
the spring of 1939, some 22 'east coast-type'CH
stations had been constructed and were fully operational.