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Notable Dates in Radio History

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Notable Dates in Radio History Radio History ----- Notable dates 1781 Luigi Galvani. First discovered that frog’s legs twitched when an electric charge was applied to them, whilst watching an assistant prepare a frog for him: it happened when the knife touched the spinal cord. Galvani correctly surmised that this was an electro-chemical process between two dissimilar metals and a liquid. 1791 He then tried attaching what we would call an aerial and an earth to them, and noted that during a thunder storm, they twitched each time there was a flash of lightning. Thus this was the first “Radio Receiver”! History has failed to honour the frog! 1865 James Clerk Maxwell. Formulated theory of radio waves: and inspired Hertz’ later work. 1879/ Anglo-American Prof. David Edward Hughes, FRS, established inventor, Inc. improved telegraph 1880 printer & carbon microphone, GAVE WORLD’s FIRST DEMONSTRATION of transmitting over 500 Yds to the Royal Society. Regrettably it was dismissed as stray coupling and he was disillusioned and gave up. But it was still the first and in the UK. 1888 Heinrich Hertz inspired by Clerk-Maxwell’s theoretical work, proved existence of radio waves, and measured properties, using a spark transmitter. Thought work of no practical use, and returned to other work. Guglielmo Marconi thought otherwise, and started experiments to see how far he could send and receive signals. -- Amateurs began experiments to see what they could achieve. Note that Marconi called himself a Radio Amateur. 1894 Oliver Lodge gave World’s first PUBLIC demonstration of radio transmission/reception. Another UK first. He also improved Branly’s detector and called it the Coherer, and used it in his experiments. 1896 Marconi moves to London with his equipment to continue his research. 1897 Lodge receives patent for “Syntonic Tuning” : ability to choose one frequency, though it is Marconi who exploits it, modified & pays no Royalties. Avaricious as ever! (See footnote on litigation). 07/1897 Marconi establishes communication between Italian cruiser San Martino & La Spezia at 10 miles. Ship beyond horizon, proof radio waves go beyond line-of-sight. 1898 The first Wireless Amateurs set up experimental transmitters in UK. 08/1908 Marconi showed that hills between the Royal Yacht and Osbourne House weakened, but did not block communication. 09/1899 Marconi: Wimereux to Chelmsford test: the sea was a 1000 ft higher than the ends of the path, thus proving the waves would follow the curve of the earth, contrary to manys’ beliefs. 17/03/1899 First distress call using Marconi radio: East Goodwin light Ship radio’d South Foreland Lighthouse that ship the Elbe had run aground. All rescued successfully. Great publicity for Marconi. 04/1900 Patent 7777 granted to Marconi for means of tuning: so that many signals could be received without mutual interference. (But see 1897: Lodge’s patent, and footnote). 12/1900 Fessenden makes first speech transmission using spark transmitter. 12/12/1901 Triumph at Newfoundland: Marconi receives signals from Poldhu, England! The Atlantic is spanned! At 1800 miles. 02/1902 Communication between UK, USA and Canada at 2099 miles at night established. About half that during day. Wavelength about 366 metres. (About 820 Kc/s, in what we call the Medium Wave). 1903 Danish engineer Valdemar Poulsen builds first successful CW transmitter (continuous wave: not to be confused with the use of “CW” for on/off transmission of Morse). 1904 Fessenden uses an alternator + quenched spark transmitter to achieve telephony at >40 km. 1904 Christian Hulsmeyer takes patent 165456 out in Dusseldorf out on what we call RADAR. Demonstrates detection of metal object (ship) at a few hundred metres. Later succeeded at ~3 km. Despite initial interest, there were no firm contracts and the idea died away. Note this was all done without any active devices as the valve was not then invented. RADAR? Or Radar, as it has become a noun, not an acronym. Radio Detection (or Direction) And Ranging. 1904 Prof. (later Sir) Ambrose Flemming uses diode valve as detector. Whilst no immediate effect on radio, this was the first use of a valve, a sign of things to come. Note however that Edison had demonstrated current in a vacuum from a hot filament in 1883: calling it the Edison Effect: but he did not exploit it. 1905 Regular news & weather broadcasts from Nordeich, Germany: in Morse! 1905 British Postmaster General issues World’s first Amateur Radio Licences. 1905 Poulsen set up AM speech transmitter in Lyngby, from which Lorenz transmitted speech to Berlin in 1909 at distance of 370 km. 1905/07 Somewhere around this time, Marconi operators note that they receive reflections of their signals from ships sailing across their paths, later in the twenties, it is noted that aircraft cause HF signals to flutter. This effect would become what we know as RADAR. (But see previous reference to Hulsmeyer in 1904). 1906 Ernst Alexanderson at General Electric (USA) gets his alternator to run at 75 Kc/s, ultimately achieving 200 KW at 100 Kc/s. (Note: Grimetown, Sweden still runs it’s at 200 Kc/s periodically. It’s a World Heritage Site). 01/09/06 Fessenden establishes first contact between Brant Rock, USA and Machniharish, Scotland. He is also credited with making the first magnetic sound recording. 1907 UK radio amateur Anthony Hankey demonstrates voice and song at a range of 29 km 1907 Lee de Forest in USA patents the “Audion” triode valve: electronic amplification is thus now possible, though no immediate use was made in radio. Slow progress at this point with the use of valves, as it wasn’t applied as we would understand it should be. 02/1908 Full commercial transatlantic service inaugurated. 1912 E H Armstrong invents the regenerative valve circuit (though here it is Marconi who patents it and exploits it for royalties…) 14/04/1912 Titanic sinks. Calls for assistance by radio, thus reducing the awful loss of life. 1917/19 Invention of the supersonic heterodyne receiver. Disputed origination: Edwin Howard Armstrong in the USA, and Lucien Levy in France. The patent dispute saw Armstrong lose. See also 1933. 1920 UK makes first high-power transmitting valves. 04/1920 Pittsburgh radio amateur Frank Conrad started playing records on-air. Given call-sign 8XK. Amazingly the big companies all failed to see the potential for broadcasting. 05/06/1920 Dame Nellie Melba performs concert at Marconi’s New Street works in Chelmsford: greatly increases interest in wireless. Received abroad as well as in UK. 1921 Radio amateurs relegated to “useless” frequencies below 200m (1.5 Mc/s): and promptly discover Short Waves! 1921 Marconi Co. permitted to make ad-hoc test transmissions from Writtle, nr. Chelmsford. Engineers were the first radio entertainers, singing, playing instruments & acting. 01/1922 GPO permitted 2MT to transmit regularly from Writtle, which lead later that year to: 18/10/22 the BBC being formed: note at that time it was the COMPANY not CORPORATION. Unlike USA, this was a public service broadcaster: not an all-commercial development. 10/1922 Prince of Wales spoke to Boy Scouts from Alexandra Palace: had enormous effect on interest in radio Other stations soon licensed: Manchester Metro-Vick 2ZY, Western Electric 2WP in London, and 5 IT in Birmingham. 14/11/22 First broadcast by BBC from Marconi House in the Strand, now to be a regular daily service. 1923 Station 2LO licensed. From May: so parallel to Writtle. Was located at Savoy Court, London. Licence permitted transmitting EITHER 11-12 am OR 2-4 pm. Generous! 1924 Spark transmitters banned in UK: their broad-band emissions caused interference at many frequencies. 1925 Pye make first enclosed radio: that is receiver, batteries and speaker in one box. 1926 First mains powered set made in UK by Gambrell Bros. 1929 Pye make first all-enclosed mains set in UK. 1931 Station names begin to appear on tuning scales. Most sets now all-enclosed. 1931 first AC/DC set appears for UK market. 1932 BBC World Service commences on 19/12/1932. 1932 BBC opens Broadcasting House. 1933 FM (frequency modulation) invented by Edwin Armstrong in USA. Sadly his patent was infringed, he got into litigation, and ended his own life. He had 42 patents, but the two most significant were contested: see 1917, as is often the case, more than one person was doing much the same thing at much the same time. 1933 Superhets now more popular than TRF receivers. 1934 Lucerne Plan implemented: European agreement on frequency allocations for stations on long and medium waves. Also UK listeners now had choice of regional or national stations. 1935/39 Roll-out of National Grid connects most UK households. ~2/3 AC, 1/3 DC. 28/01/1935 First meeting of Tizard Committee. Decided RADAR (not then called that) should be a priority for development, for GB’s air defence. This crucial decision had a great bearing on the war to come, and was against the advice to Churchill from his personal scientific adviser, Prof. Lindemann, later lord Cherwell. 26/02/35 Demonstration of RADAR using BBC’s Daventry transmitter. 09/1938 Munich Crisis. Thames estuary covered by RADAR. 1939 First “All-Dry” radio: no more acid filled accumulators, or recharging. Autumn 39 First flight of Blenheim bomber converted as night-fighter carrying 1.5 m (200 Mc/s) RADAR for night interception. Had limited range due to ground reflection: the wavelength was too great to have adequately directional antennas in the wings. 21/02/1940 Randall & Boot at Birmingham University try their Cavity Magnetron running at 3 Gc/s, or 10 cm. Immediate and spectacular success. If one device could be said to have won the war, this was it.
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