took to return from the ionosphere as an ‘echo’. To this end he successfully
used a new invention—the cathode ray tube—and he published his results in
1933 in a report called The Use of the Cathode Ray Oscilloscope in Radio
Research. But while monitoring the ionosphere, he noticed that occasionally,
he received other echoes, which appeared to come from aircraft flying in the
area of the experiment. When war seemed imminent in the late 1930s, this
experimental curiosity took on a whole new meaning as a mechanism for
detecting aircraft still at some distance from the UK mainland i.e. an ‘early
warning’ system.
To prove the practical capability of this idea, Watson Watt required the use
of a very high-powered transmitter. His original idea was to ‘pulse’ the signal
in high energy radio bursts, but only continuous transmitters existed, and still
one of the most powerful in the world was that ‘idling’ at BBC Daventry.
A test was scheduled for the morning of Tuesday, 26 February 1935. Watson
Watts’ equipment was installed in a large caravan in the meadow around the
transmitter, and an RAF bomber, a Handley-Page Heyford [K6902], was
procured and flown back and forth along a route between the two transmitter
masts. The tests went perfectly. The bomber was easily picked up and tracked
over 9 miles—a much greater ranges than had been expected. Soon, from a
laboratory on the East coast at Bawdsey Manor, new equipment was installed
which was able to detect aircraft from over 50 miles or so out to sea. From
this were developed the ‘CH’ (Chain Home) radar stations that covered the
entire East coast before the war and the whole of the British Isles by 1940.
They were not good at finding very low flying aircraft, but could find the
higher aircraft up to 120 miles away. Later, the ‘CHL’ (Chain Home Low)
stations were added to fill in the lower altitudes. These were the monsters of
radar, with huge towers (350ft or more) transmitting pulses of radio energy of
hundreds of kilowatts using demountable cooled anode transmitter valves in
the power stages and 75ft high ‘curtain’ antennae as detectors. The technology was minaturised at the GEC by the beginning of the war and their
valves formed the basis of various airborne radars.
14. Much of the information regarding the transmitters in Chap. 16 is taken
from the website maintained by retired BBC engineers at; http://bbceng.info.
I fully acknowledge their contribution here. Copyright remains with the web
authors.
15. Clayton and Algar, op. cit. (note 6), p. 119.
16. By 1957 the CAT14C was still in use at Droitwich, four in the transmitter
and nine as spares. The cost of each then was £650 and the average lifetime
was 11,000 h, op. cit. (note 6).
17. Albert Einstein famously called Haber’s life, ‘The tragedy of the German Jew,
the tragedy of unrequited love.’
18. Daniel Charles, Between Genius and Genocide, Jonathan Cape, London,
(2005), p. 219.
400
D. Sheppard
used a new invention—the cathode ray tube—and he published his results in
1933 in a report called The Use of the Cathode Ray Oscilloscope in Radio
Research. But while monitoring the ionosphere, he noticed that occasionally,
he received other echoes, which appeared to come from aircraft flying in the
area of the experiment. When war seemed imminent in the late 1930s, this
experimental curiosity took on a whole new meaning as a mechanism for
detecting aircraft still at some distance from the UK mainland i.e. an ‘early
warning’ system.
To prove the practical capability of this idea, Watson Watt required the use
of a very high-powered transmitter. His original idea was to ‘pulse’ the signal
in high energy radio bursts, but only continuous transmitters existed, and still
one of the most powerful in the world was that ‘idling’ at BBC Daventry.
A test was scheduled for the morning of Tuesday, 26 February 1935. Watson
Watts’ equipment was installed in a large caravan in the meadow around the
transmitter, and an RAF bomber, a Handley-Page Heyford [K6902], was
procured and flown back and forth along a route between the two transmitter
masts. The tests went perfectly. The bomber was easily picked up and tracked
over 9 miles—a much greater ranges than had been expected. Soon, from a
laboratory on the East coast at Bawdsey Manor, new equipment was installed
which was able to detect aircraft from over 50 miles or so out to sea. From
this were developed the ‘CH’ (Chain Home) radar stations that covered the
entire East coast before the war and the whole of the British Isles by 1940.
They were not good at finding very low flying aircraft, but could find the
higher aircraft up to 120 miles away. Later, the ‘CHL’ (Chain Home Low)
stations were added to fill in the lower altitudes. These were the monsters of
radar, with huge towers (350ft or more) transmitting pulses of radio energy of
hundreds of kilowatts using demountable cooled anode transmitter valves in
the power stages and 75ft high ‘curtain’ antennae as detectors. The technology was minaturised at the GEC by the beginning of the war and their
valves formed the basis of various airborne radars.
14. Much of the information regarding the transmitters in Chap. 16 is taken
from the website maintained by retired BBC engineers at; http://bbceng.info.
I fully acknowledge their contribution here. Copyright remains with the web
authors.
15. Clayton and Algar, op. cit. (note 6), p. 119.
16. By 1957 the CAT14C was still in use at Droitwich, four in the transmitter
and nine as spares. The cost of each then was £650 and the average lifetime
was 11,000 h, op. cit. (note 6).
17. Albert Einstein famously called Haber’s life, ‘The tragedy of the German Jew,
the tragedy of unrequited love.’
18. Daniel Charles, Between Genius and Genocide, Jonathan Cape, London,
(2005), p. 219.
400
D. Sheppard