The GR10K is an early Nixie tube manufactured by ETL in Great Britain sold under the brand name ‘Digitron’. It is identical to the GR10H except for the omission of an anode grid. While this gives the tube a highly unique and appealing appereance with great visibility of the digits, it also means that there is nothing preventing sputter from the cathodes accumulating on the inside of the glass envelope. As this happens, it forms a thin reflective layer which may eventually obstruct visibility entirely. According to its datasheet, the GR10K is a long-life tube and it does emit the characteristic blue-ish light typically associated with the inclusion of mercury vapor. This means that the tube’s effective lifespan under nominal conditions is likely limited more by sputter buildup than by cathode disintegration.
Towards the bottom of this page, I included additional pictures of two different GR10Ks. These came from a used lot and all had a red coating, which unfortunately was in poor condition. I removed it from one of the tubes, which clearly shows darkening from sputter on the inside of the glass. Another interesting difference between these tubes and the one primarily covered on this page is the fact that it includes a second digit ‘8’ in the very front. It is very likely connected to the anode and intended to make illumination more consistant across the tube’s ten digits, effectively serving the same purpose as the grid found in most Nixie tubes. Perhaps it was added in later revisions of this model to improve reliability.
Key Specifications
| Property | Description |
|---|---|
| Manufacturer | ETL |
| Time period | likely mid 1960s |
| Digit height | 19mm |
| Envelope diameter | 33mm |
| Socket | B17A |
References
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