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Bell Telephone - New Diode Speeds Voices
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The first time I saw a microwave diode in this type of ceramic package was in the detector stages of the S-band airport surveillance radar (ASR) and the X-band precision approach radar (PAR) that made up the AN/MPN-14 radar system I worked on in the U.S. Air Force back in the late 1970s / early 1980s. Both radars were primarily vacuum tube systems with a few upgrades to solid state components in areas where suitable substitutes for the original tubes were available. By the time this Bell Telephone Laboratories advertisement appeared in a 1958 issue of Popular Electronics magazine, no transistors had yet been invented for operation in the microwave realm, at least not other than the "laboratory curiosity" type. It had only been a decade since Drs. Brattain, Shockley, and Bardeen announced their invention of the first transistor. As with so many leading edge technologies, this diode was developed under a Department of Defense contract. Aside from being relatively expensive to produce, early versions were available only to applications licensed by the government because the technology was considered to be highly valuable to national security. Bell Telephone New Diode Speeds Voices at 6,000,000,000 C.P.S.
In the field of solid state science it was known - as a laboratory curiosity - that semiconductor diodes can be made not only to convert the frequency of signals, but also to amplify them. At Bell Laboratories Dr. Arthur Uhlir, Jr., and his associates calculated that this amplifying action could be put to practical use. They proved the point by developing a junction diode converter which can deliver up to 40 times as much signal energy as previous converters. This efficient new converter will be applied in a new Bell System microwave highway able to transmit thousands of telephone conversations and a dozen television programs simultaneously at six billion cycles per second. In other forms it is being developed, under Signal Corps contract, for radar and military communications where more efficient frequency conversion can also be used to advantage. This development is an example of the many different ways in which Bell Laboratories works to improve your telephone service and communications at large. Bell Telephone Laboratories World Center of Communications Research and Development
Posted September 22, 2023
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How the radio art can be improved through solid
state science is illustrated by a recent development at Bell Telephone Laboratories.
To make voice signals travel by microwaves they must first be "converted" - caused
to vibrate at billions of cycles per second. To date, it has been possible to accomplish
this conversion only at the cost of appreciable loss of signal energy. Could a more
efficient converter be provided? 
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