. The Bell System technical journal . hone Laboratories is shown in Fig. 62. This device was held to-gether by a sealing wax and string technique and was net tunable in the firstversion. It oscillated successfully on the pumps, however, and a secondversion was constructed which was tuned by means of an adjustable coaxialline shunting the cavity resonator. Adjustment of this auxiliary line gavea tuning range of Such a tuning method is fraught with the com-plications outlined in Section IX. An early reflex oscillator tube of the integral cavity type designed at theBell Telephone Laboratori
. The Bell System technical journal . hone Laboratories is shown in Fig. 62. This device was held to-gether by a sealing wax and string technique and was net tunable in the firstversion. It oscillated successfully on the pumps, however, and a secondversion was constructed which was tuned by means of an adjustable coaxialline shunting the cavity resonator. Adjustment of this auxiliary line gavea tuning range of Such a tuning method is fraught with the com-plications outlined in Section IX. An early reflex oscillator tube of the integral cavity type designed at theBell Telephone Laboratories was the Western Electric 723A/B. REFLEX OSCILLATORS 559 This design was superseded later by the 2K25 which has a greaterfrequency range and a number of design refinements. From a construc-tional point of view the two types are closely similar, however, and to avoidduplication the later tube will be described to typify a construction whichserved as a basis for a whole series of oscillators in the range from 2500 to10,000 Fig. 62.—An early continuous!} pumped metal reflex oscillator tuned with anexternal line. Before proceeding to a description of the 2K25 tube it seems desirable torecapitulate in more detail the design objectives from a mechanical pointof view. These were: 1. To provide a design which would lend itself to large scale productionand one sufficiently rugged as to be capable of withstanding the roughuse inherent in military service. 2. To provide output means which permit coupling to a wave guide insuch a manner that installation or replacement could be accomplishedin the simplest possible manner. 3. To provide a tuning mechanism for the resonant circuit which, whilesimple, would give sufficiently fine tuning to permit setting and holding 560 BELL SYSTEM TECHNICAL JOURNAL a frequency within one or two parts in 10,000. In addition, in orderto avoid field installation it was desired to have the tuning mechanismcheap enough to be factory installed and
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
