Maybe it's Thorium, used in the filaments. On Wednesday, November 4, 2020 at 4:13:16 AM UTC-8 Paolo Cravero wrote:
> Hi. > Let me add two pictures and a story. > > Lately I picked up locally a bunch of small CRTs (2BP1, that also fit in > the vintage tuner currently on eBay, plus a Marantz) and the guy had a few > NIB tubes too. I was looking for gas-filled ones and that resulted in a > W.E. 6167 dekatron, some 0B2WA and some W.E. 6140/423A. Of particular > interest was the 6140 shown in the picture whose box mentions Kr85, but no > symbol on the glass. > When I came home I checked with a Geiger counter and SBM-20 probe (hard > beta and gamma particles) these tubes and the 6140 from 11/61 shows no > action. Same goes for other 6140 except for one, much older from 12/52 > marked 423A. Neither the box nor the glass carry any warning sign, but this > tube hits >600 CPM vs 40 CPM background when put close to the SBM-20 probe > (it's not the right way to measure radiation, but it's cool :) ). There is > definitely something else than Kr-85 in there! I have blurred pics of it > and it has been stored away from home. > > As already mentioned, Nixies did contain Kr-85 and I knew I had one > clearly marked. It's a Burroughs Self-Scan display that probably needed > some "doping" to handle the almost 1 MHz scan rate. BTW, it contains gas > and I might never use it, so if someone wants to experiment with self-scan > contact me off the list. > > One question for the knowledgeable people in here. I have some Mullard > Nixies marked "Kr-0A": has it got something to do with Kr-85? I can't check > with the Geiger since my probe does not detect Kr-85 leftovers. > > So, if you are on the hunt for active tubes, better look for unmarked > pre-1960 editions and carry a Geiger counter with you ;) > > Paolo > -- 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 on the web, visit https://groups.google.com/d/msgid/neonixie-l/227e71bd-4626-4d00-9edd-e4adf7a36d8cn%40googlegroups.com.
