ELECTRON TUBES FOR A COAXIAL SYSTEM 



1115 



add materially to the cost of tube construction and testing. Early in the L3 

 tube development the question of factory cost compared with circuit per- 

 formance was weighed and it was decided that the advantage of lower tube 

 cost plus the very large advantage of simple plug-in tubes would outweigh 



(1939) 



(J943) 



(1949) 



Fig. 8— The 386A, 408A,, 

 actual size. 



404A, 435A, 436A and the 437A tubes approximately 



the cost in performance. Accordingly, all three L3 tubes are of the stiff 

 pin, plug-in type designed to fit existing sockets. The price paid for obtain- 

 ing the advantages of lowered cost and interchangeability has been a loss 

 in feedback of approximately 2 db per amplifier. 



