The Ericsson GPE120T is a cold cathode trigger tube. The Z805U is said to be a close match to the characteristics of this tube but this may be in error as the data-sheet gives the anode as pin 4 whereas in this tube pin four has no electride connected to it,
The electrodes on the right are a curved plate shielding a rod.
The curved plate and rod.
The thin glass tube envelope is 21 mm in diameter and, excluding the B9A base pins, is 46 mm tall.
