1298 THE BELL SYSTEM TECHNICAL JOURNAL, NOVEMBER 1956 



HELIX 



CONNECTOR 



TUBE 



HELIX LEAD 

 INSULATOR 

 \ 



BEAM FORMING 

 ELECTRODE 



^- GLAZE BOND 



-ACCELERATOR 



1.64" 



CATHODE 

 SUPPORT WIRES, 

 THREE AT 120° ~ 

 SPACING 



i 



HELIX LEAD- 



GLAZE BONDS 



METAL RIBBON HAS THREE TABS 



AT 120° SPACING WHICH ARE 



LATER WELDED TO COUPLER ON 



HELIX ASSEMBLY 



SUPPORT WIRES, THREE 



CONNECTED TO EACH 



ELECTRODE 



AT 120° SPACING 



-^ GLAZE BONDS 



CERAMIC 

 SUPPORT PLATFORM 



HEATER 



CATHODE 



OUTER CATHODE 

 ALIGNMENT CYLINDER 



- — INSULATOR 



---__ INNER CATHODE 



ALIGNMENT CYLINDER | 



Fig. 8 — M1789 electron gun assembly. In constructing the gun, all the parts 

 with the exception of the cathode, heater, and inner support cylinder are mounted 

 on a mandrel which fixes their relative positions. Glass powder is applied to the 

 areas where glazed joints are desired. The unit is then heated in forming gas 

 (85% No ,15% H2) to 1.00°C to melt the glass and form the glazed bonds. With 

 this technique the precision required for alignment and spacing of the electrodes 

 resides entirely in the tools. The helix connector tube later slides into the coupler 

 detail of Fig. 14 to align gun and helix assemblies. The inner and outer cathode 

 alignment cylinders are welded together at two points at the end remote from the 

 cathode. Optical comparator inspection shows that the significant dimensions of 

 these guns are held to a tolerance of less than ±2 mils. 



