The D7/201GH is a small oscilloscope cathode ray tube. Brimar in the 1960s were a leading maker of oscilloscope tubes. We do not as yet have operating details but the D7/200GH is very similar and will be a close approximation to this tube.
The B13B all glass base has the evacuation seal in the centre. The pins can be seen to be composite with the red platinum section having a coefficient of expansion that matched that of the hard glass base.
The neck of the tube is semi-frosted and this gives a blurred image of the electrostatic gun assembly.
The screen is rectangular and shows signs of phosphor burn. Burns occur when a non varying image is in place for a protracted period or if the image is produced at high intensity.
The end window envelope is 61 mm X 55 mm. The tube neck is 33 mm in diameter, and excluding the base pins is 170 mm long.
Updated August 12, 2016.