The T5890 CRT is an analogue oscilloscope storage tube, The 202 indicates the standard phosphor - green. This tube came from a Tektronix 549 mainframe oscilloscope. This 1966 device used both valves and semiconductors and weighed 68 pounds and consumed 600 Watts. The 549 had a vertical bandwidth of 30 MHz and the design was discontinued in 1972.
The Type 549 Storage Oscilloscope was a laboratory instrument to operate with all Tektronix letter-series or one-series plug-in units. The cathode ray tube used in the Type 549 is a direct view, bistable storage tube having a 60 X 100 mm display area, divided into two 30 X 100 mm targets. The targets are independently controlled for split screen applications. An additional area which does not store is provided to the left of the targets. This area functions as a locate zone in single sweep store mode. (Tektronix, Manual 549, 1966.)
The mu-metal shield and the optically flat tube face.
The contacts for the storage mechanism that is close to the face-plate. Storage is accomplished with a second 'flood gun' as well as a fine wire mesh at the screen behind the phosphor.
The gun assembly is in a 50 mm diameter tube and the neck widens to 60 mm for the deflection plates and anodes.
A closer view of the cathode and part of the electron optics.
The flat cathode is within the cylinder on the right. The beam emerges through the circular hole.
A closer view of the Y plates.
The 14 pin base with key on the central spigot.
The flat face-plate is 140 mm in diameter. The trace is formed in the central area and the surround is gold.
This shows the original 549 oscilloscope.
Both handles are required to move this 'scope. The ventilation through the sides is also essential.
The tube in place within the mainframe.
The end window envelope is 50 & 60 mm in diameter, and excluding the base pins is 450 mm tall.
References: Internet, Wikipedia and 549 manual. Type T5890-202 was first introduced in 1966.