The Z504s is a small cold cathode decade counting tube that has a direct read-out from the end window and a maximum counting speed of 5 kHZ.
The ten main cathodes are arranged around the circumference of a circle. Between the cathodes are guide electrodes. Once the gas discharge has begun around an cathode it will stay in that place. To count a voltage is applied to the guide electrodes and the next cathode. The discharge walks from one cathode to the next. Situated at the end of the count is an electrode that acts to pass a pulse on to the next counting tube but at a tenth of the input frequency. These devices were popular in the 1950s and 1960s before the advent of low cost digital circuits. The operating voltage was usually in the region of 150 Volts.
A side view showing the ceramic support, the parallel connection of the guides and the insulation around the cathode leads.
Top or face view of cathodes and guides. The anode is the central disc. In use the active cathode glows orange.
The end window envelope is 30 mm in diameter and, excluding the base pins, is 34 mm tall.
Reference: Datasheet. Type Z504S was first introduced in 1961.