Dolam LC-516

The LC-516, produced by Polish tube manufacturer Dolam (later known as Unitra Dolam), is pin-compatible with and visually similar to the Soviet IN-1 Nixie tube. However, unlike the IN-1, an early model with a relatively short lifespan, the LC-516 contains small amounts of mercury, which significantly improves its longevity and gives its discharge a subtle bluish tint. The LC-516 features a slightly smaller glass envelope and digits compared to the IN-1; a comparison between the two is shown below. Notably, the LC-516 has a black base, which is also found in IN-1s intended for export. Dolam also manufactured a version without the phenolic base under the designation LC-513.

As I am not aware of a datasheet specifically for this tube, I have provided a link to the IN-1’s datasheet below. Since the tubes are compatible, the relevant specifications should be identical. The earliest samples of LC-516 I have seen were manufactured in 1971.

Update from 2025-05-18

I was able to acquire a slightly different version of the LC-516, featuring a larger glass envelope and digit sizes comparable to the IN-1. This variant appears to lack mercury vapor and has a slightly different digit arrangement. I suspect it may be an earlier revision of the model. Photos are provided below.