- Up To The Start Of The Broadcasting Era -

by Greg Whiter, VK
4IG (Ex VK3CA)


Page 6 of 7 - Alexanderson, RCA and Paul Godley

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. Alexanderson RF AlteratorSo 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 Rotary Spark Unitsometime 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 neighbors 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 RCA's 1922 Logoactivities 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 Rinartzwireless 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 17th 1919 the Radio Corporation of America (RCA) was formed as a wholly U.S. owned company. On November 20th 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 fullyRinartz Regenerative Receiver Circuit 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), (PDF file with the full story of Godley's achievements from a February 1922 QST Magazine article)  (PDF file giving the full story of Station 1BCG's achievements from a February 1922 QST Magazine article) 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.

 Paul Godley

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?









Appendix - Evolution Of The Radio Valve In Radio Transmission Systems
The use of "soft" (not fully evacuated) valves was generally appreciated in radio receivers.

1915  Successful telephony experiments between America and Paris. The need was recognized for higher powered transmitting valves, with consequently higher vacuum. Forty to fifty watts was not a big enough valve anode rating to achieve long distance telegraphy at the low frequencies then in use.

191 Ship radio installations were still using mostly used arc transmitters. New ships began to be fitted with valve transmitters and receivers. The production of "hard" (high vacuum) valves had commenced, and in June of that year, signals were successfully sent between Portsmouth (England) and Gibraltar. In that case the tungsten anodes of the valves were worked at 2000 volts, and a current of about 10 amps. was obtained in an aerial having a total resistance of 5 ohms.

1917    The English Marconi-Osram Co. commenced production of transmitting valves for the British Admiralty, and glass valves with anode dissipations of up to 150 watts were being made in this year. French authorities issued thousands of small valve transmitters and receivers for use in the First World War battlefields.

1919    The obsolescence of the spark transmitter definitely began. CW (Continuous Wave) transmission was in general use in big stations, usually produced by the Poulsen arc or HF Alternator. Silica enveloped valves were introduced, those with an anode dissipation of 1 kW being quite common.

1920   Thermionic valves were still somewhat limited in power capability and only used in small transmitters, since it was uneconomical to use a large number of small valves in parallel.

1922   Experimental valves rated at 100 kW had been produced, but 500 watt glass bulb transmitting valves were still the most common. Crystal control of frequency began to develop from this year.

1923   Demountable transmitting valves were produced, and two rated at 10 kW were installed at the Eiffel Tower.

1924   The beginning of the HF (High Frequency) era of commercial radio communication. Successful telephony between Poldhu (England) and Sydney (Australia). The invention of the copper-glass valve seal enabled a great increase to take place in the anode rating of valves; the anode became accessible and could be water jacketed in order to cool it.

1927    The British GPO (Post Office) opened a transatlantic telephone service using the "single side band" (SSB) system of transmission. The power of the transmitter was about 100 kW, and the final amplifier stage at first included thirty 10 kW water-cooled valves.

1931    A 500 kW demountable valve was installed experimentally in the GPO single side band transmitter.


“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 – February 1922, May 1934, December 1940, January 1964 – ARRL.
“CQ” magazine – November 1959 – Cowan Publishing Corporation.
“The Superheterodyne Receiver” – 1941 – Alfred T. Witts.


Next Page - Australian Radio Pioneer - Ernest Fisk

Other Web Articles by the same author   EARLY YAESU MUSEN EQUIPMENT IN AUSTRALIA 


History Of Radio HOME PAGE

Links to other pages in this article
Page 1  In The Beginning - Static Electricity - 600 BC
Page 2  The Leyden Jar to Magnetism
Page 3  Samuel Morse To Heinrich Hertz
Page 4  Edourad Branly To Lee De Forest
Page 5  SS Republic to ARRL - PDF Article "Greatest Of All Amateurs - Marconi" by Hiram P Maxim - ARRL from Sept. 1922 QST article
Page 6  Alexanderson, RCA and Paul Godley - PDF Article "Story Of Godley's Achievements" from Feb 1922 1922 QST article
Page 7  Australian Radio Pioneer - Ernest Fisk


Any comments on this article should be directed to the author, Greg Whiter at: GregWhiter@portablemasts.com.au

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