The GR-211 is a large Nixie tube produced by Rodan-Okaya in Japan. It ranks as the third-largest Nixie tube made by Rodan and succeeded the short-lived GR-11. Later models were rebranded as CD94. Notably, the GR-211 includes a left decimal point, which is uncommon for tubes of its size. In devices using larger Nixie tubes, a separate neon bulb typically represented the comma instead. Interestingly, the datasheet marks the decimal point’s pin as “not connected.”

The R|Z568M is a massive modern Nixie tube produced by Dalibor Farný and his company. Each tube is manufactured by hand in the Czech Republic. As the name suggests, its design is meant to be reminiscent of the Z568M, the largest Nixie tube produced in the GDR. A picture below shows a comparison between the R|Z568M, an original Z568M, and a Z566M. Despite being the smallest of the three, the Z566M, with its 30mm digit height, is still considered a large tube. This makes the impressive scale of the R|Z568M, featuring 50mm digits, even more striking. The manufacturing process of an R|Z568M tube is documented in this video.

The Z566M is a large Nixie tube manufactured by RFT. It is pin compatible with the ZM1040 but differs in design, featuring a flatter top and a top-evacuation design, though some earlier units were evacuated from the bottom. In some instances, Z566Ms have even been rebranded and sold as ZM1040s. A variant without the pre-applied red filter was marketed as the Z5660M.

The Z566M was primarily utilized in laboratory equipment such as voltmeters and frequency counters. Its large size also made it well-suited for devices designed for use in educational settings, such as schools. A Nixie tube featuring various symbols, designed to complement the Z566M/Z5660M, was marketed under the names Z567M and Z5670M.

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 is mercury-doped, significantly enhancing its durability and giving its glow 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. Additionally, Dolam manufactured a version without the phenolic base, designated as the LC-513.

The National Union GI-10 is likely the first Nixie tube ever produced, belonging to National Union’s Inditron series of display tubes. Patented applied for in 1954 (and granted in 1956), it predates the original “NIXI” tube developed by Haydu Brothers and later Burroughs by at least a few months. Similar to other early Nixie tubes, such as the STC GN-1, its digits are not stamped from sheet metal but are crafted from wire. These digits are connected to the tube’s 10 pins via long rods covered in an insulating layer of ceramic that also serve to hold them in place. In contrast to more modern Nixie tubes, where the digits are arranged to minimize obstruction of each other, the digits in the GI-10 are organized in a straightforward, sequential manner. The zero digit is positioned at the very front, while the one is located at the farthest point in the stack. Unlike most later Nixie designs, the GI-10 lacks a dedicated anode; instead, activating a specific digit requires all other electrodes to be held at anode potential, which complicates the driving circuitry and makes it difficult to achieve uniform brightness across all digits. The tube uses a standard Noval 9-pin socket with an additional central pin.

The GR10H is an early Nixie tube produced by ETL, featuring digits visible through a small viewing window, with the majority of its envelope coated in black paint—likely intended to enhance contrast and minimize light bleed from adjacent tubes. Pictures posted on jb-electronics.de show a clear GR10H revealing that, like the STC GN-1, the digits are connected to the tube’s pins via thick wires.

Unfortunately, this particular unit shows significant wear and requires increased current to maintain a stable discharge.

The GN-1, manufactured by STC and sold under the name ‘Nodistron’, was among the earliest commercially available Nixie tubes. The oldest documentation I could locate dates back to December 1959 (referenced below). The tube’s design reflects its age, with the digits being formed from wire rather than stamped from sheet metal like in most later Nixies. The GN-1 emits a distinctly orange glow, indicative of a mercury-free design, which likely results in a shorter lifespan compared to later models. Unlike more modern Nixie tubes, the GN-1 includes two evaporative getters, clearly visible on the left and right sides of the glass envelope. Additionally, its numerals are not mounted on a metal pin insulated by spacers but are instead secured between two mica plates and connected to the tube’s pins via thick wires. Interestingly, according to the datasheet, the tube has two anodes for use with direct and alternating currrent respectively.