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BELL SYSTEM TECHNICAL JOURNAL 



pressor grids and the mid-point of the filament circuit and the other 

 being connected to the screen grids. Slots in these sheets provide space 

 to mount the tube elements. The capacitance between the two closely 



Fig. 1 — An early experimental type tube. 



spaced sheets forms an effective radio-frequency by-pass condenser 

 between the screen grids and the filaments. Fig. 2 is a section view 



Fig. 2 — Section view of the tube shown in Fig. 1. 



through the middle of the tube showing the disposition of the elements. 

 While entirely satisfactory from an operating viewpoint, this design 

 proved to be rather difficult to fabricate. 



