RADIO EXTENSION LINKS TO TELEPHONE SYSTEM 



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showed that transoceanic telephony was possible and indicated some 

 of the difficulties that had to be overcome. 



The radio transmitter in these tests deserves a few words because 

 of its novelty and because in one respect it has never been equaled. 

 The carrier was modulated at a relatively low level and then amplified. 

 The final stage of amplification contained 550 tubes in parallel which 

 in number appears to be an all time record. Each tube was capable of 

 delivering only 15 or 20 watts peak h.f. power which would give a 

 power rating on a telephone basis of about 2^ kw. 



With these tests completed, transoceanic telephony withdrew into 

 the laboratory for almost eight years while further intensive work 

 was carried out. The second step in public occurred in January 1923 



Fig. 1 — The first transoceanic radio telephone circuit opened for 

 commercial use January 7, 1927. 



when a second transoceanic test was made. A 200 kw. single sideband 

 transmitter had been constructed and installed at Rocky Point, Long 

 Island, while engineers with receiving equipment journeyed to London. 

 A demonstration was given to government engineers and to newspaper 

 reporters over there to show that practical transoceanic telephony 

 was possible and to interest them in constructing a return circuit. 

 The British government was interested and with our assistance took 

 up the matter of providing a transmitter and receiver for their end. 

 Three years were required for this third step and in February 1926 

 the first two-way radio telephone conversations were held between the 

 United States and England. Commercial service opened in January 

 1927. See Fig. 1. 



