Hi, I've recently purchased interesting tubes: 5 unused LC-7 tubes made by Dolam. While they don't look spectacular, they are extremely rare. Googling in English and Polish leads to only two places over the internet where these tubes are mentioned. This thread on Polish forum: http://www.trioda.com/forum/viewtopic.php?f=9&t=19611 Note the lack of word "nixie" in the discussion, official Polish name for nixies is "wskaźnik jarzeniowy". That makes googling this tube even harder. And this auction I've purchased them from: http://allegro.pl/zestaw-5-lamp-nixie-dolam-lc-7-i6845565730.html
So, they aren't popular, rarer than LC-1 and LC-2, which were used comercially (LC-2, at least, source: http://www.mif.pg.gda.pl/homepages/jasiu/oldtr/OTL/index.html). The holy grail would be an LL-1, which exists so far only as "being prepared for production" in some old documents. There is no known commercial equipment using LC-7. There is no information about time of their production. There are some codes on the back on the tube, but they don't make much sense, as they go: xW 0812, NJ 2409, NT 8617, NW 4204 and NY 530x (x stands for unreadable). The codes have different style from other Dolam nixies, which have codes consisting of two letters and two digits. It is very possible, that these are prototypes of LC-531, as they are very similar. The differences are: LC-7 doesn't have a pill on the top It has different stack of digits and pinout It has only right decimal point* Digits are slightly taller and slimmer It has polished outside of back plate (very reflective) It seems to contain no mercury (pure orange glow, no blue haze) Different voltage requirement - I didn't make many tests, but the sustaining voltage is betwen 150V and 155V. I didn't measure striking voltage. What is similar: They have nearly identical size and internal structure Both have 13 wire base, same diameter, same style (circle divided in 14 parts, one wire missing) *If the theory about LC-7 being a prototype of LC-531 is true, it might exlain why only the right decimal point is mentioned in LC-531 datasheet - LC-7 has only that one. I've taken some photos and made a pinout for the tube. On many photos I'm comparing it to a LC-531 to make the difference more clear. LC-531 is on the left, and LC-7 on the right. Sorry for bad quality - I'm not a photographer and I have no skill in creating good lightning for photos. I've uploaded my "work" to our google drive to TEMP/Dolam LC-7. https://drive.google.com/drive/u/1/folders/0B4bzn8WGaWL1Q0ZDNXhOZUtkblk Here's the pinout for quicker search: <https://lh3.googleusercontent.com/-m2xn6CU9anY/WVVZLLZdf4I/AAAAAAAACMU/_IMec3JZVyQTw4rLBYUYYs1slyDFFGgtACLcBGAs/s1600/DSC04553.JPG> Arrow shows the front of the tube. It is almost exactly between those two pins. And two photos for general overview (right photo shows LC-531 on the left, LC-7 on the right): <https://lh3.googleusercontent.com/-oPhktOi70AA/WVVZpGdMJgI/AAAAAAAACMc/VX5VmnFwhsoW3scwzX61ynCQ1qjo-NRdgCLcBGAs/s1600/DSC04535.JPG> I'd like to make this thread & drive folder a comprehensive source of data about the tube. So if you'd like to see a photo from different angle, or with different lightning*, or just have any question - just ask me. *if you have any tips how to photograph nixies without using manual white balance, I'd like to read them - I can't choose non-automatic white balance and it is ps. I know that these photos take alot of space. If the photos take too much space, I will try to find a way to share my own folder with neonixie google drive drive. -- 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 post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/89762bf2-9238-4900-94d4-43cf7748c8f2%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
