The GN-1 nixie tube is an early example made by STC of England. Because it is among the first nixie tubes, it does not have mercury added, so it is a short life tube. Another indication of the age of this design is that the digits are made from formed wire, rather than being stamped out of a sheet. You can also see from the photographs that it came in at least two variants – one had a dark anode, the other a light anode.

The Lorenz datasheet indicates that there are two anodes; one for DC use and one for AC use. The datasheet is at the end, and I have included an English translation

Digit size 25.5mm
Min current 2.5mA
Max current 5mA
Base B12A

The (Lorenz) datasheet

GN-1 Datasheet

English translation of datasheet

1. Operating Values (notes 1 & 2)

a) For DC voltage

Anode voltage Ua 200 250 300 V
Anode resistance Ra 18 33 47
Cathode current Ik 3.5 3.5 3.5 mA

b) For half-wave alternating voltage

Anode voltage Ua 200 240 300 V
Anode resistance Ra 8.2 10 22
Cathode current Ik 3 3 3 mA

c) For alternating voltage

Anode voltage Ua 220 240 300 V
Anode resistance Ra 27 33 56
Cathode current Ik 3 3 3 mA

Note 1)

The tube must not be operated without anode resistance. also for uniform illumination of the numbers in the cathode 1, turn on a resistor of approx. 80% of the anode resistance.

Note 2)

In AC operation, the DC anode a= is over 220kΩ to connect with the AC anode a~.

2. Limits

Minimum supply voltage UBmin 200 V
Maximum anode current Iamax 5 mA
Minimum anode current lamin 2.5 mA
Minimum erase voltage Uemin 120 V

3. Special instructions

As a supply voltage, the highest voltage available in the device with a suitably sized anode resistance should be used to minimize the differences in the current and thus in the brightness due to scattering and lifetime of the tube.

The circuit should be designed so that the non-operated cathodes are either turned off or put to a potential that they can not act as anodes against the operated cathode.

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