This oscilloscope cathode ray tube from Hivac has no colloidal graphite internal coating and thus the gun assembly is totally visible.
On test the heater was found between pins 3 and 4 and when powered came to an orange red at 2.0 Volts and 2.0 Amps. No operating details have yet been located but the HT is probably 800 - 1,000 Volts.
The CRT is a three inch model and the curved faceplate is 78 mm in diameter.
The etched identification, Hivac name and Made in England.
The cathode cylinder on the right, accelerating anodes and focus anode plus the two pairs of deflection plates. With a small deflection angle the plates are not flared. All the gun components are held accurately in place on ceramic rods.
The final anode has a small round exit window.
The end window envelope is 35 mm in diameter and, excluding the B7 base pins, is 270 mm tall.
References: Observation and Test. Type CR3 was first introduced in 1938.