The CV1097 seen here is marked with the stores code 10E/222. This 6 inch green phosphor cathode ray tube was designed especially for WWII airborne radar and the prototype was the VCR97. It was first used in 1940 in the ASV range amplitude display. The phosphor type is P1 medium persistence. The CV2810 is the same tube but with a short persistence violet phosphor beneath a longer persistence green phosphor.
The CV2286 is very similar physically but has an EHT connector on the side of the bell. This may be to connect to the final anode or it could be an early example of post deflection acceleration.
An advert for Premier Radio in Wireless World August, 1948 confirms that the VCR97 is equal to the Mullard ECR60.
Pin 7 is the internal graphite 'Aquadag'coating. The design specification is for A1, A3 and the coating to be tied together and manufacturers could elect to do this at manufacturing stage. The connection would be to pin 10 as the final anode.
The heater cathode insulation was not designed to withstand high voltages and so the heater supply would be floating. The standard practice was to hold the final anode at earth potential or that of the deflection amplifier HT rail. This leaves the cathode at about 2.5 kV below ground.
The B12D base and electron gun. The pinch is circular with a re-entrant centre section and can be seen just above the base plastic.
This tube is constructed with a ceramic ring to hold the electrodes in place. The ceramic ring is clamped to the pinch stem. The red part of the lead-out wire that passes through the glass can be seen within the centre of the ceramic ring.
The 6 inch screen is curved so as to withstand the forces on the glass. A flat un-laminated faceplate would implode.
The curvature of the screen.
The base. The side contacts mate with flat metal strips in the base. Correct location of the tube is by means of the keyway. Inside the removable base plate is the evacuation tube and wires that are soldered to the contacts. A common fault in these tubes was a failure of the cement holding the base to the glass neck. This would often cause a break in a wire that could be repaired by un-screwing the base and re-soldering.