The Dawn of Amateur Radio in the U.K. and Greece | Page 6

cycles (10 kHz) at extremely low current and because of the skin effect suffered no harm.
One of Tesla's patents related to a system of lighting using glass tubes filled with fluorine (not neon) excited by H.F.voltages. His workshop was lit by this method. Several years before Wilhelm Roentgen demonstrated his system of X-rays Tesla had been taking photographs of the bones in his hand and his foot from up to 40 feet away using H.F.currents.
More astonishing still is the fact that in 1893, two years before Marconi demonstrated his system of wireless signaling, Tesla had built a model boat in which he combined power to drive it with radio control and robotics. He put the small boat in a lake in Madison Square Gardens in New York. Standing on the shore with a control box, he invited onlookers to suggest movements. He was able to make the boat go forwards and backwards and round in circles. We all know how model cars and aircraft are controlled by radio today, but when Tesla did it a century ago the motor car had not been invented, and the only method by which man could cover long distances was on horseback!
Many people believe that a modification of Tesla's `Magnifying Transmitter' was used by the Soviet Union when suddenly one day in October 1976 they produced an amazing noise which blotted out all radio transmissions between 6 and 20 MHz. (The Woodpecker) The B.B.C., the N.B.C. and most broadcasting and telecommunication organisations of the world complained to Moscow (the noise had persisted continuously for 10 hours on the first day), but all the Russians would say in reply was that they were carrying out an experiment. At first nobody seemed to know what they were doing because it was obviously not intended as another form of jamming of foreign broadcasts, an old Russian custom as we all know.
It is believed that in the pursuit of his life's ambition to send power through the earth without the use of wires, Tesla had achieved a small measure of success at E.L.F. (extremely low frequencies) of the order of 7 to 12 Hz. These frequencies are at present used by the military for communicating with submarines submerged in the oceans of the world.
Tesla's career and private life have remained something of a mystery. He lived alone and shunned public life. He never read any of his papers before academic institutions, though he was friendly with some journalists who wrote sensational stories about him. They said he was terrified of microbes and that when he ate out at a restaurant he would ask for a number of clean napkins to wipe the cutlery and the glasses he drank out of. For the last 20 years of his life until he died during World War II in 1943 he lived the life of a semi-recluse, with a pigeon as his only companion. A disastrous fire had destroyed his workshops and many of his experimental models and all his papers were lost for ever.
Tesla had moved to Colorado Springs where he built his largest ever coil which was 52 feet in diameter. He studied all the different forms of lightning in his unsuccessful quest for the transmission of power without wires.
In Yugoslavia, Tesla is a national hero and a well-equipped museum in Belgrade contains abundant proof of the genius of this extraordinary man.

CHAPTER TWO
THE BIRTH OF RADIO COMMUNICATIONS
By 1850 most of the basic electrical phenomena had been investigated. However, James Clerk Maxwell (1831-1879), Professor of Experimental Physics at Cambridge then came up with something entirely new. By some elegant mathematics he had shown the probable existence of electromagnetic waves of radiation. But it was twenty four years later (eight years after Maxwell's death) that Heinrich Hertz (1857-1894) in Germany gave a practical demonstration of the accuracy of this theory. He generated and detected electromagnetic waves across the length of his laboratory on a wavelength of approximately one metre. His own photograph of the equipment he had set up can be seen in the Deutsches Museum in Munich.
To detect the electromagnetic waves Hertz employed a simple form of oscillator, which he termed a resonator. But it was not sensitive enough to detect waves at any great distance. Before wireless telegraphy could become practicable, a more delicate detector was necessary.
Credit is due to Edouard Branly (1844-1940) of France for producing the first practical instrument for detecting Hertzian waves, the coherer. It consisted of two metal cylinders with leads attached, fitted tightly into the interior of a glass tube containing iron or steel filings. The instant an electric discharge of any sort occurred the coherer became conductive, and if it was tapped lightly its conducting property was immediately destroyed. In practice the tapping was done automatically by a tapper which came into action