Welcome! My IN-18 clock has 14 tubes. One of them is from 1977, and the others are from 1989. I cant see any difference in their appearance. They have been running for just over 2 years and I have no problems with any of them. In my opinion, the IN-18 is the best-value in terms of cost vs size.
I once read somewhere that IN-18 tubes built in 1982 and 1986 had some reliability problems, but I can't remember where I saw that. I know that my tubes built in 1989 have soft pins that have mild surface corrosion (it seems harmless) and are easily bent, whereas the 1977 tube has stiffer pins that have a corrosion-resistant finish. I dont know who your seller is, but since you are in Germany, I'm guessing it could be Dieter. If it is, follow his advice on which tube to use. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/45fec4d6-16f8-4f51-ae4e-a37ded8c2aab%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.