Hi, TM maintanance is quite expensive (bearings), but it lasts quite long time. If You want to use polyphenyl ether (Santovac?) You will have to pay quite a lot of for it. The same with cold trap - liquid nitrogen on the site necessary (or cooling device).. But as I mentioned, the oil molecules are not a problem for nixie manufacture. I use bake out in oven followed by induction heating of the internal parts (no bombardment), so even if there is some oil, it will break down. 10E-10 mbar is a dream, but it needs a NASA-like lab ;-)
I guess they used diff pumps, at least Tesla did. I found that the pressure in small audio tubes just before seal-off was 10E-2 mbar (quite poor vacuum), then the getter was flashed and got the tube to ~10E-7 torr. Big transmitting tubes were made on different machines, pumped long times to proper vacuum (10E-6 mbar) using cold traps.. Dalibor 2015-02-11 13:07 GMT+01:00 Nick <n...@desmith.net>: > On Wednesday, 11 February 2015 11:28:07 UTC, Dalibor wrote: >> >> Nick: Hi, I use TM because I was lucky to get few for reasonable price >> from local bancrupted research company, together with all the accessories. >> Diff pump are much cheaper, they need practically no maintenance (when used >> right way), but they it takes much longer time to start it up and also the >> cool down. TM is more flexible in this way and saves a lot of time, >> especially during development. And TM pump also provides oil-free operation, >> which is good, but essential matter in nixie tube making. > > > Hi Dalibor - thanks for the feedback. I have no doubt that a TM is a lot > faster & cleaner, but they do spin ever so fast and still need > maintenance... > > Diff pumps with suitable low vapour-pressure oil, e.g. a polyphenyl ether, > which is changed/maintained properly should be fine - no oil should get back > to the glass if you get the sequencing right and the bombarding (or > equivalent) should remove any potential organic matter - I can't see that > more than a few molecules should ever get back to the tube... Modern > multi-stage diffusion pumps with a cold-trap will reach 10x10-13 atm, which > is far far below what we need - > > When nixies were commercially manufactured, did Burroughs/National etc. use > TM or diffusion pumping? > > Cheers > > Nick > > -- > You received this message because you are subscribed to a topic in the > Google Groups "neonixie-l" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/neonixie-l/9a5d2ICHZA8/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > neonixie-l+unsubscr...@googlegroups.com. > To post to this group, send email to neonixie-l@googlegroups.com. > To view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/20d654ef-5a7e-4769-b84c-285fa968442b%40googlegroups.com. > For more options, visit https://groups.google.com/d/optout. -- Dalibor Farny ---------------------------------------- phone: +420 724 321 571 http://www.daliborfarny.com FB: https://www.facebook.com/daliborfarnycom -- 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/CA%2BnkT5pbonu4iER0P_CJCAQ2xUrwfk%2BkfKpOwsBLMdw9sm914A%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
