402 BELL SYSTEM TECHNICAL JOURNAL 



repeater tubes of various types be designed to operate at a fixed plate 

 voltage. For this reason the design of ampHfier tubes to give as 

 large a power output as possible at the operating plate voltage is of 

 considerable importance. 



In the case of three-electrode tubes it is possible from theoretical 

 considerations to compute, approximately, the electrical parameters 

 a tube must have in order to give the maximum output power of a 

 given quality obtainable under fixed operating conditions. 



The electrical characteristics and output of fundamental, second, 

 and third harmonics of two of the more common telephone repeater 

 tubes are given. 



It is of considerable interest to determine whether greater power 

 output of comparable quality can be obtained from tubes containing 

 more than one grid. Since no sufficiently exact theoretical analysis 

 of multi-grid tubes is yet available to permit the determination of 

 the parameters of optimum tubes, a comparative experimental inves- 

 tigation of a number of such structures has been undertaken. The 

 electrical characteristics and output of fundamental, second, and third 

 harmonics of several such experimental tubes are given. The power 

 output of multi-grid tubes and of three-element tubes is compared. 

 The reasons for the comparatively large power output of certain types 

 of multi-grid tubes are discussed. 



Effect of Small Quantities of Third Elements on the Aging of Lead- 

 Antimony Alloys}^ Earle E. Schumacher, G. M. Bouton, and 

 Lawrence Ferguson. The data presented in this paper definitely 

 show that small quantities of certain elements when added to lead — 1 

 per cent antimony alloys have a very marked effect on the rate at which 

 antimony is precipitated from supersaturated solid solution. Some 

 suggestions of the mechanism of this change can be had from a consider- 

 ation of the experimental findings in conjunction with the pertinent 

 equilibrium diagrams. 



Although the literature shows that the third elements studied are 

 insoluble in lead in the solid phase, no results have been reported on 

 alloys containing these elements in very low concentrations. Even 

 though they should be insoluble in lead, antimony may so change the 

 lead lattice that they become soluble in lead-antimony. Furthermore, 

 since these elements form either compounds or solid solutions with anti- 

 mony, there are forces of attraction between them which may be 

 strong enough to carry small quantities of the third elements, along 

 with the antimony, into solid solution in the lead. The resulting ter- 



^" Indust. and Eng. Cliem., Nov. 1929. 



