Nixie Clock vs Raytheon CK1916 tubes

[Matthew]

Glad to find this group again... a few years since I did any of this stuff, before the move to Google Groups!

I'm working on a couple of clocks, based on Jonas's kit at TubeHobby.com. I really like the kit, having made two before - it's documented for IN-14 and IN-18 tubes, but mine were with IN-12 and IN-16, both working well without any modifications (other than physical).

This time I'm trying to make one with come CK1916 tubes I found on eBay - they are very attractive. However, when wired up, they just don't seem to fire at all :( I found the following datasheet on Dieter's site: http://www.tube-tester.com/sites/nixie/dat_arch/Raytheon-data.pdf and they seem to have similar specs to the Russian tubes, but I'm having no luck so far.

Does anyone have any experience with these tubes, or any ideas? If I sound clueless, it's because I am :) I'm more into making the cases than understanding the electronics!

[Nick]

The CK1916 is equivalent to an NL841 and is indeed a nice tube - it has a left hand DP - the NL840 differers only in having no DP.

This tubes should (probably) work fine - there is (probably) something else wrong... Have you checked you've still got HT at about 180V?

Nick

[Dieter Waechter]

It's a well known problem with the 1916's.

I have about 500 NIB, and most of them show that problem.

Most need a high firing voltage (200 V and up) and some are completely dead.

The only thing I can imagine is gas leakage.

I have experienced that problem on some other American made tubes, but oddly ONLY at American made tubes (I recall National and Raytheon).

Dieter

[Nick]

Interesting - Have you seen this with NL840-class tubes?

Nick

[Dieter Waechter]

Hmm... I don't remember the NL- types, sorry.
But I know that I saw that on RTS-11 type tubes.
And especially the CK1916 and the CK1923.
Dieter

[Matthew]

Thank you all for your replies! Dieter, thank you both for providing the original datasheet, and for your suggestion - increasing the voltage seems to have done the trick. Jonas's kit suggests using 160v which has worked fine for all the Russian tubes (rated at 170v), but at 190v I seem to get reliable illumination of these tubes.

I guess I should have just tried! But again, I'm not that well up on the electronics side - I wasn't sure what kind of voltage is safe for me and/or the tubes, didn't want to blow anything up!