ELECTRON TUBES FOR A COAXIAL SYSTEM 



1117 



mica and element assembly is then mounted upon a glass stem or platform 

 which is next sealed into a glass bulb after which the exhaust and activation 

 procedures complete the tube. These cutaway views show that these L3 

 system tubes are very similar to conventional tubes. The reason for want- 

 ing to continue with the conventional type structures is simply that of tube 



END SHIELD 



CONVENTIONAL 

 SCREEN GRID 



-MICA DISK 

 FRAME GRID 



Fig. 10 — Cutaway view of the 436A. 



cost. A production line such as that for the W.E. 408A or 6AK5 tubes 

 could very readily be changed over to any one of these tubes. The only 

 change needed would be in the control grid supply and in the dimensional 

 control procedures. 



The principal distinctive design feature in these tubes, compared to 

 earlier repeater tubes, is the "frame" type of control grid which was first 

 introduced in a somewhat different form in the W.E. 404A4 and W.E. 



4 ''The 404A- A Broadband Amplifier Tube," G. T. Ford, Bell Laboratories Record, Vol. 

 XXVII Feb. 1949. 



