Early Electronic Television
The set uses a magnetic deflection/electrostatic focus CRT called a "Doppelblendenrohr" - double diaphragm tube. The tube is the RFB VI/1 which was manufactured in 1937.
In the above diagram, H = filament, 4 volts. K = cathode, 0 to 250 volts
(brightness control). W = control grid (wehnelt). HA = Screen grid (hilfsanode),
about 300 volts.
Bl.1 = focus diaphragm (blende 1),
600 to 1200 volts (focus control). A = Anode, E.H.T. 8 KV.
This CRT has an electrostatic lens, consisting of two diaphragms, for focusing the electron beam.
Below is the schematic diagram of the FE-VI-1
(click on pictures for high resolution images)