| Descrizione |
Tyne page 319ff: H.W. Freeman, of Westinghouse Electric & Manufacturing Company, in an article published in December 1922, described an indirectly heated cathode tube which was double ended. A.M. Nicolson, of Western Electric, constructed indirectly heated cathode tubes in 1914 (see Chapter 6). In July 1925 samples of Freeman's tube were submitted to RCA. In April 1926 more samples were obtained. In June 1926 the designation UC225 was assigned to this tube, and RCA placed orders for 1000 tubes at each of the three tube factories. During November Westinghouse suggested the use of a five-pin base to eliminate the necessity for the adopted for detector applications, and the five-pin base was aproved. With the adoption of this base the desigantion UX225 was changed to AY225 and then for commercial reasons to AY227, and finally to UY227. On May 21, 1927, the UY227 was announced in New York newspapers. ... The first UY227s had sheet-metal anodes and were subject to grid emission difficulties. Westinghouse engineers suggested that the use of a mesh anode would eliminate this trouble, and the change was soon made. Shipments to RCA began early in the Summer of 1927.
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