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Alan Blumlein: Wartime Radio Pioneer

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Alan Blumlein: Wartime Radio Pioneer Alan Blumlein: wartime radio pioneer to design, develop and install a working designed the Air Interception (Al) radar EMI, including Blumlein. There was no system ready for the BBC launch "in system, which operated automatically. EMI gear on V9977. But there had been November 1936. By May 1937 the EMI By the spring of 1941 they had improv- much debate over whether the H,S test U team had produced outside broadcast ed the accuracy of Al radar sufficiently flights should use magnetrons or equipment which could transmit King for one aircraft to detect another in the klystrons. Winston Churchill was worried George VI's coronation the first ever - air several kilometres away. But it is like- in case the magnetron, which was vir- television broadcast from outside a ly that from as early as 1937, Blumlein's tually indestructible, might fall into studio. real aim was to develop a "plan position enemy hands if there should be a crash. In January 1935, while EMI team the indicator" an airborne radar, that could The fated bomber, Halifax V9977, was was starting work on the 405 -line all - display a picture of the ground or sea fitted with a magnetron and the flight on electronic TV system, Robert (later Sir) below. Some people believe Blumlein June 7 was made solely so that the EMI Watson -Watt was working on a commit- succeeded in this as early as 1938. team could see how the prototype H,S tee, chaired by Henry Tizard, for the Accuracy and clarity of the image magnetron equipment worked at high Scientific Survey Air of Defence. They depended on the frequency and power altitude. were looking for a "death ray" to defend of the signals used. The higher the fre- The Halifax was flying at around 2500 against air attack. quency, the smaller the wavelength, the feet when disaster struck. The starboard But in February 1935 Watson -Watt smaller the aerial needed, and the higher outer engine failed, because an inlet wrote his now famous memorandum the resolution of the system. The valve fractured due to metal fatigue. saying that although it was impossible to This breakthrough came with the invention of engine was driving the generator which destroy aircraft by radio waves, it should the magnetron and the klystron; the supplied power to the H,S equipment. be possible to detect them by radio former was a carefully sculptured So instead of feathering the propeller, the crew tried to re-start its engine. But it caught fire. The crew then tried to put out the fire, but found the extinguishers had not been filled. The plane crashed at 4.20pm killing everyone on board. The J ...,... only piece of equipment to survive the I' crash was the magnetron. But it did not fall into enemy hands. Today, plan position radar, like Al radar, television, stereo sound and numerous electronic circuits designed by Blumlein are taken for granted. It would be fitting to end on the note that An original "Emitron" camera tube, as used for the first regular TV service, 1936. although Blumlein died young, his inven- tions live on. But sadly, although his energy reflected from the aircraft's body. chamber within which high frequency name will doubtless be found on a few Using BBC's transmitter at Daventry, he oscillatory signals of great power could commemorative plaques, his memory is proved that detection by reflection was be generated; the klystron was an elec- revered only by a handful of people who possible. Immediately, in the early spring tronic circuit that achieved the same have taken the trouble to read what they of 1935, the whole project was covered result, but with less efficiency. By early can about his life and work. The real . with a security blanket of high secrecy. 1942 the work on the plan position radar tragedy of Blumlein's life is that by the It is unclear exactly when Blumlein and (code -named H,S) by EMI at Hayes and time we wake up to his genius it will be the EMI team became involved in the THE at Malvern was bearing fruit. too late to document that genius for development but he filed many patents On June 7, 1942 Halifax V9977 took off posterity. on radar circuits in the late 1930s, even from Defford crammed with experimen- This article first in though (for security reasons) they were tal H,S gear. There were five crew appeared "New Scientist", 3rd June, 1982 and is réproduced here with not printed until 1946 and 1947. And we members, half Sir Bernard Lovell's permission from the publishers. ° IPC do know that by 1940 Blumlein had engineering team and three men from Magazines, 1982. fvndme,sMilº of SOLID STATE ELECTRONICS AUSTRALIA HANDBOOKS FUNDAMENTALS OF SOLID STATE provides a wealth of information on semiconductor theory and operation, delv- ing much deeper than very elementary works, but without the maths and abstract theory which make many of the more specialised texts very heavy going. It's for anyone who wants to know Just a little bit more about the operation BASIC of semiconductor devices. ELECTRONICS BASIC ELECTRONICS Is almost certainly the most widely used manual on electronic +r fundamentals in Australia. It is used by radio clubs, in secondary schools and colleges, and in WIA youth radio clubs. Begins with the electron, introduces and explains com- ponents and circuit concepts, and progresses through radio, audio techniques, servic- ing, test instruments, etc If you've always wanted to become involved in electronics, 104,111111111. but have been scared off by the mysteries involved, let Basic Electronics explain them to you. x6 Available horn "Electronics Australia", 57 Regent St, Chippendale, NSW. PRICE 53.50 each OR by mail order from "Electronics Australia", PO Box 163, Chippendale, 2008. PRICE 4.40 each. ELECTRONICS Australia, March, 1983 19 .
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