The XL601 is a cold cathode glow modulator with an average current rating and a peak current of 45 mA. The discharge is confined to a thin hollow cathode and the light approximates to a point source. The light output is approximately linear with current.
Typical use would be in fax machines and photo-electric counters. This exhibit will be built into a through the air transmitter with an 80 mm diameter Fresnel lens.
The anode cap sitting on top of the ceramic tube with the cathode tube within.
A closer view of the construction.
This design has a flat end window. The cathode tube can be seen in the ceramic insulator.
The pinch and mica supports.
The wide glass envelope is 29 mm in diameter and, excluding the IO base pins, is 59 mm tall.
Reference: Data-sheet. Type XL601 was first introduced in 1970.