--- In NEONIXIE-L@..., michail1@... wrote:
I have a bunch of Russian and Chinese tubes. The china are terrible.
You would even think they were used and suffering from cathode poisoning (and
maybe they are), but many do this within a month. I just chalk it up as a
China problem so that I don't get upset about it.
Note about your IN-18 tubes. I have purchased and sold many factory
sealed boxes before. I have noticed a huge difference in tubes appearing used
and new in the same box. So, although you didn't purchase from me, it is
possible you did not get used tubes. I am still amazed at how many (within
the same batch/same box) have tubes with the Digit 1 blue spots. Also
pretty amazing is the height difference in the manufacturing size of the glass
envelope (up to 4mm range) -- again within the same batch (all matching
number of prod dates and OTK, etc.
Michail
Thanks for the comments, Michail.
About the IN-18. I wrote a post a few months ago about these. Basically I see three signs of use on the IN-18:
1. darkening of the insulating spacer washers on the support rods between the digits.
2. darkening of the mica support disks (mostly the darkening appears on the top mica disk).
3. darkening of the glass near the rectangular openings in the anode cage on the left and right sides.
I think that #1 can occur just with factory burn-in and test procedures.
But I would be surprised to see darkening of the glass unless many hours of use had occurred.
The mica disks I'm not sure about. I have some Z566M that have darkened mica and significantly darkened ceramic washers. These were also supposed to be new, and Jan at Ask Jan First states that they are new. I tend to believe him.
Perhaps you can tell us if new sealed boxes of IN-18 show darkening observation (as described above):
#1 ?
#2 ?
#3 ?
Thanks.
