With its 40mm digits, the IN-18 (“NH-18”) is the largest Nixie tube mass-manufactured in the Soviet Union. It shares the same envelope diameter with smaller Nixie tubes, such as the ZM1040 and Z566M, which gives the IN-18’s digits a slightly elongated appearance. Today, the IN-18 is among the most popular Nixie tubes, often used in large Nixie clocks. Although vast quantities were manufactured and remain readily available on online marketplaces like eBay, IN-18 tubes have become quite expensive. Unlike many Soviet Nixie tubes, the IN-18 features a proper cathode for the number five rather than an inverted two. Its gas mixture includes trace amounts of mercury vapor, which significantly extends the tube’s lifespan and imparts a faint bluish tint to its glow.
Curiously, despite their large production numbers, I have only ever encountered a single period device that actually utilized IN-18 tubes. The tube pictured below is a used example, evident from the slightly bent pins and the sputter deposits visible on either side of the envelope.
Key Specifications
| Property | Description |
|---|---|
| Manufacturer | Gazotron |
| Time period | ? |
| Digit height | 40mm |
| Envelope diameter | 31mm |
| Envelope height | 71mm |
| Socket | PL31 |
References
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