What kind of Nixie Tubes are these?

[Dman777]

My friend found this...he saids the tubes are 1-7/8" in diameter...what kind of tubes are these that they are this large?

[gregebert]

NICE FIND !! Tubes that large are quite rare. They look like Burroughs tubes, but the size is too large for a 6091, and a bit small for a 8091.

Can you find any markings on them ?

Just in case your friend doesn't know what to do with them, I could give them a good home where they will be prominently displayed and well cared-for.....

[Dman777]

My friend suspects they are Natonal Electronics NL 8091.... what are you thoughts on these? I told them if they are, they are rare and extremely valuable.

[gregebert]

If they are NL8091 tubes, they are supposedly very similar to Burroughs. The Burroughs datasheet says you can run them at 170V DC, with a 5.6K series resistor, so you should test them to see their condition. Despite their value, if I had these I would never sell them. Instead I'd make a 4-digit clock and keep the 5th as a spare.