The XN3 is a medium-sized Nixie tube manufactured by Hivac in Great Britain and Lorenz in Germany and part of their ‘Numicator’ line of display tubes. According to its datasheet, it is the direct successor to the XN1, featuring pin compatibility and primarily differing in its increased lifespan. Unlike many later long-life tubes, however, the XN3’s discharge does not exhibit the characteristic bluish glow associated with mercury vapor. The XN3 also lacks the evaporative getter present in some XN1 units; instead, it uses a more conventional, non-evaporative getter positioned at the tube’s top, typical of Nixie tubes. Like the XN1, its anode cage restricts digit visibility, making the display primarily readable from straight-on viewing angles. In addition to the transparent version shown below, a variant coated in a red filter was also produced.

The XN1 is an early Nixie tube produced by Hivac in Great Britain and Lorenz in Germany. The earliest documentation referencing this tube I could find is dated September 9, 1961, shortly after the invention of Nixie tubes. This particular unit features an evaporative getter at the top, giving it a distinctive appearance typically associated with vacuum tubes (often seen in VFDs). However, versions with a getter located behind the anode cage were also manufactured. The tube’s anode cage is notably restrictive, limiting visibility to mostly straight-on angles. Unlike many other tubes of similar size, the XN1 does not include any decimal points.