A cylindrical coding tube for 8-digit code

The cylindrical coding tube discussed in this paper has been designed for converting a sampled analog signal into a digital signal of reflected binary (Gray) code. The physical principle of the tube is one of electron-optical image formation in a coaxially symmetrical electric field, similar to 45°-focusing in a homogeneous field. This principle leads to a minimum of image errors. The voltages applied to the tube remain below 250 volts, the control voltage being smaller than 65 volts. The current pulses are decoupled on eight discrete collectors. The signal sampling frequency may go up to 10 Mc and higher. The tube is relatively sturdy in its physical construction, the cathode being designed for a long life expectancy. The tube assembly is 65 mm in diameter, 250 mm long, and has a weight of less than 300 gms.