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Despite initial problems, De Forest's Audion valve was to have a major impact on the development of radio. Regular broadcasts began in the early 1920s and, in Australia, scores of radio manufacturers sprang up to cater for the public demand. By JOHN HILL Last month, I covered some of the more significant developments in early radio - from Hertz' discovery of radio waves to De Forest's revolutionary "Audion" valve. We will continue where we left off. De Forest's early Auctions were not very good. The idea was great, but the implementation of the idea was let down by the valve not being made properly. It was soon discovered that radio valves required precision manufacture, with the placement of the various components being fairly critical. Another problem was that a sufficient degree of vacuum could not be attained within the glass envelope of the valve and the remaining gas interfered with its operation. Plate voltages in excess of 30 volts caused ionisation of the enclosed gases and the tube emitted a blue glow and ceased to function. Although the Audion was conceived in 1906, it was not commercially available until 1911. There were quite a few problems to sort out. The previously mentioned vacuum problem was solved by Arnold and Langmuir's research for better vacuums for electric light bulbs. Their independent efforts helped the Audion and a few other early valves along the way. During this early development period, the Audion's performance was pretty mediocre. It also faced strong 6 SILICON CHIP competition from the newly discovered crystal detector. The crystal detector was good for its price, required no batteries and didn't burn out. Crystal receivers were to become the poor man's radio for quite some period of time. Patent infringements There were other problems that De Forest had to face and one that caused him great frustration was the question of patent infringements. Marconi held the patent for Fleming's diode or twoelement valve, while De Forest held the patent for his recently discovered third element, the grid. Marconi claimed that De Forest's Audion infringed his patent but, at the same time, was himself unable to use De Forest's grid because of that particular patent. Both parties were in a bind. Apparently there was a brief period where attempts were made to sidestep these patents. Even valves with external plates were tried - anything to get over the opposition's patents. Eventually, everything sorted itself out. Lee De Forest had considerable foresight regarding the new science of radio and many of his ideas were well ahead of the times. He, like fellow countryman Reginald Fessendon, was interested in wireless This Kriesler radio of about 1948 vintage has survived the last 40 years quite well. It used a bakelite cabinet which is much more durable than plastic. telegraphy. As early as 1907, De Forest had devised a means of modulating a spark transmitter so as to broadcast speech. It must be realised that, at this stage of radio development, headphones were in use and the coherer was well on the way out. The US Navy placed orders for De Forest's unique equipment and it was sold with a five-mile (8km) guarantee. Actually, it had much better range than the guarantee promised. In 1908, De Forest gave a demonstration broadcast from the Eiffle Tower in Paris using his "Radiophone" transmitter. This historical broadcast was received as far away as 800 kilometres. Following up his success in Paris, the De Forest Radio Telephone Company began a series of broadcasts complete with singers and musicians. Two complete operas were broadcast and even the great Caruso sang in one of these extraordinary radio programs. However, impressive and all as these magnificent broadcasts were, they were mostly a waste of time for the simple reason that only a handful of amateur radio operators heard them. Once again, Lee De Forest was ahead of his time. Regular broadcasting was still about 10 years down the track, on the other side of the First World War. In the meantime, the American Telephone and Telegraph Company purchased the sole rights to De Forest's Audion and used it to relay long distance telephone messages. Radio was very much in the experimental stage during the first two decades of this century and both transmitters and receivers were few and far between. Even those who might have a radio receiver could only look forward to listening to occasional Morse transmissions. · ocean going vessels carried radio. As a result, the value of radio was brought to notice on several occasions. In 1909, the liner Republic rammed the Florida and began to sink. The wireless operator on the Republic radioed for help and received a quick response from nearby ships. All but six of the passengers and crew were saved. Such an incident did much to promote radio and bring it to the public notice. The above shipping mishap resulted in the American Congress passing an act requiring ships to carry radio equipment. Another shipping disaster occurred in 1912 when the Titanic struck an iceberg and sank in the North Atlantic with the loss of 1500 lives. Once again, the wireless operator on board the Titanic sent out a distress signal (in this case, the first SOS) which was picked up by the Carpathia. Although the Carpathia was quite some distance away, she arrived in time to save many survivors who would otherwise have perished. It is not generally known, but there was another ship much closer to the Titanic. Many more lives could have been saved if the wireless operator had been on duty at the time the distress signals were transmitted. This incident resulted in an amendment to the American Radio Act of 1910. The amendment required that ships have two radio operators on board so that a continuous 24-hour watch could be maintained. Broadcasts begin Back on dry land again, nothing much happened as far as broadcasting was concerned until 1919, when Dr Frank Conrad (an amateur radio buff and Westinghouse engineer) began broadcasting radio programs from a makeshift station in his garage. These programs consisted mostly of gramophone records and were very well received by other amateurs. Because of his regular broadcasts, Conrad received considerable correspondence and newspaper praise. Some of the local Pittsburgh papers even published transmission times. Had they Shipping disasters Ship to shore communication was the first really practical use radio was put to and a good many ships . were equipped with radio, even during the very early stages of its development. As early as 1910, most large You'll need a good collection of valves to start restoring vintage radios. These are still in their original cartons. Al'HIL 1988 7 This under-chassis view of a restored receiver clearly shows the wiring techniques employed. The major components were mounted directly on the chassis and the minor components (resistors and capacitors) strung between them. had some idea of the impact the coming radio boom would have on newspaper circulations, they may not have been so anxious to freely advertise Conrad's programs. One can only guess at the quality of the sound reproduction of Conrad's broadcasts. What with acoustic recordings played on a gramophone, it must have been little better than noise at the receiving end. However, such was the success of Conrad's regular backyard broadcasts his fellow Westinghouse colleagues decided to build a transmitter of their own at the Pittsburgh factory. It went pn the air in 1920 with the callsign KDKA. As far as American radio was concerned, KDKA was the real beginning of commercial radio and it grew at an incredible rate. In 1920 there was but one station; by 1924, there were 1400 stations. Now that's progress! The 1920s must have been the radio industry's boom time, for once broadcasting really got going, it became an immediate success. These early broadcasts operated at rather low power with most stations operating at levels well below 500 watts. 100 watts was quite common. With so little radiated energy, the ratio between static and signal strength was extremely high, resulting in distant programs being impossible to listen to because of interference from atmospheric and man-made electrical disturbances. The problem caused by static was gradually overcome by increasing the wattage of broadcasting sta8 SILICON CI-IIJJ tions. Such a move helped to tip the balance of the static to signal ratio more in favour of the listener. Broadcasting in Australia was not far behind the rest of the world and two stations were on the air towards the end of 1922. It was a repeat performance of the American scene and radio was readily received by an eager public. By 1930, there were dozens of stations on the air. Radios and radio components were all imported at first but this situation did not last long. Local manufacturers sprang up like mushrooms. Within a corn~ paratively short time, the Australia radio industry was in full swing and scores of radio manufacturers, both large and small, were producing radios from mostly Australian made components. Looking back to the turn of the century and the early development of radio, perhaps the most amazing aspect of it is the speed at which it all happened. It is also pretty obvious that it was radio that gave birth to the electronics industry as we know it today. Radio was the stepping stone to bigger and better things. Although the development of radio is just another frontier conquered, there seems to be something about radio that is difficult to explain. The fact that it works from afar without any visible connection between transmitter and receiver gives it a mystic quality. It is understandable why early researchers referred to it as "The Wonder of Wireless". Next month, we start collecting and restoring vintage radios. ic