WHERE DID IT ALL START? A CHRONOLOGICAL HISTORY OF THE DEVELOPMENT OF RADIO 
- Up To The Start Of The Broadcasting Era - 
by Greg Whiter, VK3CA

1914 - 1919  ALEXANDERSON’S Alternator – World War 1. Ernst F. W. Alexanderson, Swedish-American, had helped Fessenden build some of his earlier alternators. With this background, Alexanderson was able to improve the alternator so that “smooth” continuous waves of frequencies from 50,000 to 100,000 Cycles per second (we know them as hertz today) could be generated. So great were the possibilities of these new alternators that Marconi himself came to the G.E. laboratory to see a demonstration. As a result the British Marconi Company began negotiating for the machine, but a stalemate in negotiations was reached when the U.S. entered World War 1 and seized or closed down all private wireless stations. Throughout the war wireless was of substantial aid to both sides as a means of constant communication and as an aid to espionage. In the United States the A.T.&T. Co. was hard at work perfecting the vacuum tube, the rights to which it had purchased from de Forest. The tube’s ability to function as an “oscillator”, or generator of high frequencies, was established by that time, by virtue of de Forest’s and Armstrong’s feedback circuits. A means of modulating voice on the carrier wave that was produced, also by vacuum tubes, was developed in 1914-15 in the G.E. Labs. by Alexanderson and in the Western Electric Labs. by Colpitts. Hartley, working for Western Electric, Co. in 1915 also developed the Hartley oscillator circuit.

These inventions resulted in experiments in radiotelephony, for the purpose of facilitating and improving long distance speech. The first test was made by Bell telephone engineers in 1915. A low power transmitter was used on wavelengths of 800 to 1800 metres. The results achieved were good enough to warrant further tests with higher power.

While initial tests used tubes giving 15 watts power output, before the end of 1915 several hundred such tubes (sometimes as many as 500) were paralleled to achieve high power. Larger transmitting tubes of the order of 100, 500 or 1000 watts were not developed until sometime later. As a result of all of this research, in 1915 the first trans-Atlantic (and, accidentally trans-Pacific to Honolulu) radiotelephone conversations were successfully held between Arlington, Va. and the Eiffel Tower in Paris. In these test the U.S. Navy, Western Electric and A.T.&T. Co. all collaborated.

All of this was the forerunner to broadcasting, which commercially didn’t make its appearance until 1920-21. The technical developments in speech transmission without wires during this period were to point the way for the broadcast industry that was to soon explode.

Frank Conrad, in 1919, a Pittsburgh amateur and Westinghouse engineer, began broadcasting recorded music from his amateur telephony station located in a garage at the rear of his house. His broadcasts were received with such great enthusiasm by other amateurs in the vicinity, who invited their friends and neighbours over to hear the “wireless music”, that much newspaper publicity was given to his broadcasts. As a result, Westinghouse officials, in 1920 decided to build a large station to conduct broadcasting for the publicity and prestige it would bring to the company. Station construction was rushed so that it was launched in time for the Harding-Cox presidential election returns. This station later became the very well known KDKA. Broadcasting in the U.S. went from one station in 1920 to 400 in 1922 and then to over 1400 stations in 1924.

1919 - 1921  Formation of the Radio Corporation of America (RCA). Until 1919 the British Marconi Company had dominated in all activities of the American wireless field (in Australia it had been Telefunken and Marconi who’s government forced marriage resulted in the formation of AWA). Their early start and strong finances permitted them to buy up and control all major patents and activities. After World War 1, the Marconi Company resumed its negotiations for the Alexanderson alternator. The United States government intervened. It was felt at the time, that the sale of American patents might result in the domination of wireless communication by foreign interests. After conferring with the navy, a meeting was held at the General Electric office, where it was decided to retain the alternator in the interests of the U.S. It was likely also, at this meeting plans were formulated for the formation of a strictly American-owned radio company. At any rate on October 17^th 1919 the Radio Corporation of America (RCA) was formed as a wholly U.S. owned company. On November 20^th the assets and business of the British-owned Marconi Wireless and Telegraph Company of America were taken over by RCA. From this time RCA held the patent on DeForest’s triode valve and the Westinghouse patents of Armstrong and Fessenden on heterodyne reception. They also cross licensed patents with AT&T in order to centralise all intellectual property needed to commercialise broadcast radio (RCA used their patents for one-way broadcasting, AT&T used theirs for two-way telephony).

By the early 1920’s radio had well and truly arrived, with most of the general public now fully conversant with its capabilities. The 1920’s brought many refinements in valve circuit technique, for example Rinartz’s superior regenerative receiver, Armstrong’s superegenerative and superhetrodyne receivers as well as the neutrodyne receiver. By opening up low power trans-Atlantic communication, the amateurs, through Paul Godley (using Armstrong’s superhet receiver), proved how useful the “useless” shortwave bands were. The full story of these and other milestones in radio’s continued development, including the growth of broadcasting, further advancement of the vacuum tube, as well as development of circuit techniques and parts, arrival of the crystal triode (transistor) in 1948, will all have to wait for another time and another article.

It had only taken 2500 years for radio to arrive. One can’t help but wonder what the next 2500 years will do for the art of communication?

BIBLIOGRAPHY

“Radio-Craft” – March 1938 – Hugo Gernsback, Editor.
“200 Metres & Down” – 1936  - Clinton B. DeSoto.
“Handbook of Technical Instruction for Wireless Telegraphists” – Third Edition 1925 – J. C. Hawkhead.
“Handbook of Wireless Telegraphy – 1938 – Admiralty.
“Radio Physics Course” – 1930 –Alfred A. Ghirardi.
“QST” magazine – May 1934, December 1940, January 1964 – ARRL.
“CQ” magazine – November 1959 – Cowan Publishing Corporation.
“The Superheterodyne Receiver” – 1941 – Alfred T. Witts.