DAVISSON CATHODE RAY TELEVISION TUBE 



859 



is added and cross connected to Mi and Mi as indicated in Fig. 1(c). Now 

 when signal voltage is applied, the electron beam is displaced, rather than 

 deflected, across the aperture S', and the portion of the beam entering the 

 projection lens system is maintained in proper alignment with the tube 

 axis. 



The complete electron-optical system of the tube is indicated schemati- 

 cally in Fig. 2. A dimensional cross section of the tube is shown in Fig. 3, 



Fig. 4 — Photograph of tube details, 

 (a). Photograph of coUimating unit, 

 (b). Photograph of modulating unit. 



while Figs. 4 and 5 show mechanical details of the assembly. Figure 6 shows 

 the finished tube, held by Mr. Calbick. 



Referring to Fig. 2*, the plates Pa , A , -P2 



P2 and Pr are metallically 

 connected together with separating metallic cylinders to form the struc- 

 tural ''frame" of the entire electrode assembly. They are connected to the 

 internal Aquadag coating and held at ground potential. 



The backing plate Pi , filament F, and circular aperture plates Pi and P2 

 constitute the electron source and condensing lens system whose function 



* This diagram actually shows the electrode voltages used in a later model for 441 line 

 pictures. In tiie 240 line tube the anode voltage was 5000 volts. 



