Absolutely correct! The Russian tubes are metric. The USA tubes are in inches. Close but not an exact match. Using the incorrect socket puts a stress on the pins and will crack the glass. The glass seals around the pins are by far the most delicate part of a tube. Avoid heat and mechanical stress on tube pins. I have learned this the hard way over the past 40 years!
On Wednesday, August 6, 2025 at 5:16:21 PM UTC-4 Dekatron42 wrote: > There are slight differences between the B5991/2 and the IN-12A/B pin > spacing according to datashets, dimensions can be found here: > > IN-12: IN-12A_IN-12B_03.pdf > <https://www.tube-tester.com/sites/nixie/dat_arch/IN-12A_IN-12B_03.pdf> > > B5991: https://frank.pocnet.net/sheets/116/b/B5991.pdf > > Overall dimensions is in inches on the B5991 and millimeter on the IN-12 > which makes the two tubes almost fit in each others sockets. The sockets > I've tested puts a lot of strain on the pins possibly leading to cracks in > the seals of the tube pins if pressed in to hard, either directly or over > time. The Burroughs type has a total lengthwise distance of 0.68 inches > whoch si close to 17.3mm whereas the IN-12 is specified at 18mm, the other > direction the Burroughs types is 11.2mm whereas the IN-12 is 11.5 (not much > of a difference) but the other way it is almost 0.7mm which is quite a lot. > > Neither do I recommend cutting off pins on Nixie tubes as that will > probably lead to cracks in the seal, there are flying lead Nixies like the > B5750 or IN-16 and even on those you shouldn't cut the pins to close to the > glass seal nor should you solder to close to the glass seal as the high > temperature from the soldering iron might lead to cracks as the pins expand > in the glass seal. > > Since I discovered this difference I've always used the correct sockets > for the specified Nixie, or used single pins. > > /Martin > > > > On Wednesday, 6 August 2025 at 01:37:28 UTC+2 Michail Wilson wrote: > >> Hello, >> >> >> >> Pin 13 and 14 are not used. Most sockets (if not all) will have an open >> area for the pins to slide in even if no connection is made. For that >> tube, you could literally simply cut them down (carefully) so you don’t >> have to worry about it like in the circuit design you included a picture of >> (pcbway?). >> >> >> >> Very few tubes use those pins (like the B5971) so finding the sockets >> loaded with all 14 holes is rare in itself. When I spot them on ebay, I >> snag them (for no real reason other than just knowing they’re rare). I >> love the auctions where people post pictures of tubes with sockets (14 pin >> complete) and selling for the cost of a $5-$10 tube. Those sockets are >> worth more than the tube itself. >> >> >> >> I believe the 5991 is pin compatible with the IN-12 (That is IN-12A. >> The IN-12B uses pin 12 for the leading decimal point where the 5991 and >> IN-12A don’t have it. >> >> >> >> (So, unless you’re using a B5971, you don’t need sockets with pin 13/14 >> loaded with connecting gear) >> >> >> >> M1 >> >> >> >> *From:* [email protected] <[email protected]> *On Behalf >> Of *Tom Lang >> *Sent:* Sunday, August 3, 2025 9:45 AM >> *To:* neonixie-l <[email protected]> >> *Subject:* [neonixie-l] Re: Newcomer From Asheville, NC 5991 vs IN-12 >> >> >> >> Some insight as I was thinking about this. I looked at some pcb >> sockets. Apparently pins 13 and 14 are not carried thru the actual socket >> itself. This would imply that as long as the tubes were not directly >> soldered onto the pcb board itself (I would expect no one to do this) a >> board for the IN-12 could accommodate a 5991 after all?? >> >> On Sunday, August 3, 2025 at 12:35:37 PM UTC-4 Tom Lang wrote: >> >> I'm a retired electrical engineer familiar with designing and building >> vacuum tube amplifiers. This is my first foray into the nixie tube clock >> world. >> >> >> >> I want to use the Burroughs 5991 tube on some pcb boards designed for the >> IN-12 tube. I have looked and looked but cannot find definitive answers as >> to physical interchangeability of the two especially on prefabricated pcb >> boards designed for the IN-12. At this time I do not have any of the tubes >> or boards on hand. >> >> >> >> It appears (see attachments) that the 5991 has two extra pins 13 & 14 >> that would have to be accommodated if one were to utilize a 5991 on a board >> for the IN-12. However, the picture of the "tube adapters" implies >> otherwise (where's the holes for 13 and 14?). Also it DOES appear that >> chassis mount sockets (such as the brown ones shown) do have relief holes >> for the extra 5991 pins. >> >> >> >> There are attractive prices for premade boards for the IN-12 tubes that I >> probably would purchase if they are compatible with the 5991. However, I >> don't mind having to use chassis mounted sockets and flying leads if >> necessary for the 5991. >> >> >> >> Thanks for your help. >> >> -- >> 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 [email protected]. >> To view this discussion, visit >> https://groups.google.com/d/msgid/neonixie-l/f5f96fac-3906-4457-996d-54749fd39815n%40googlegroups.com >> >> <https://groups.google.com/d/msgid/neonixie-l/f5f96fac-3906-4457-996d-54749fd39815n%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> > -- 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 [email protected]. To view this discussion, visit https://groups.google.com/d/msgid/neonixie-l/4df433e6-34c7-4dc0-9265-d718acbbc8e4n%40googlegroups.com.
