Hi there,
Just came across this page ! I assumed EEVBlog was more about modern electronics but I am glad to see that this forum has grown so huge over the years, that the old stuff now enjoys a sufficient audience to generate many and interesting threads !
Took my time and went through all 12 pages with great interest. These 7 segment nixies are incredible ! OK, it seems they were called "lumitron" or something, if I understood you correctly. Come to think of it they were very common place a few years back. I used to see them all the time at gas stations, the pumps would display fuel quantity and price on these nice displays.
I also loved this Russian piece of gear on the first page IIRC, with its mat black aluminium facia, it looks superb. Makes the nixies really stand out, beautifies them. I love this black + nixie combination, wish the "western" manufacturers used it at least sometimes back then, rather than the same aluminium theme all the time.
Anyway. after 15/20 years of sleep, my passion for electronics eventually woke up, 12 months ago. I started searching for gear to equip the bench. A couple a months or so ago while doing my daily search for local/French stuff, I came across a nixie counter ! First nixie piece of gear in 12 months of daily search !!! Was complete and in great nick, full featured, decent spec (20MHz 5 digits), in working order, not dirt cheap but reasonably priced, I just couldn't resist the temptation, bought it !!!
It's a Schlumberger, 1971 vintage IIRC, model FM 2502. The seller was an old engineer who bought it brand new back then, hence he still had the original user manual and schematics for it ! This alone is a treasure... normally on these old French instruments you can never find the schematics, never mind a full manual !
It also features a 5 digit pre-scaler as you can see on the pics.
Seller was super nice, we kept exchanging e-mails. said he was clearing his lab of many of his older instruments to make room for more modern instruments... 69 year old but still very actively working in his lab ! Doing RF stuff mostly, but anyway. Said he had already sold most of his old stuff but that he still had one nixie instrument left, that I might find interesting.... indeed it was interesting, bought it in a heart beat !!! Another counter. So that's 2 nixie counters in one go !
It's a Metrix DX 446A. What got me excited was the performance of the thing compared to the other counter : not 5 but 8 digits, wow, and 160MHz ! Without a prescaler ! AC coupled though, but I tested it and it starts working from as low as 120kHz.
Again, fully working and with full original documentation, a gem.
Obviously I have since learned, confirmed on here, about the marvelous HP 53XX series ! Sure want one of those ! The 5340 at least, with it's 20GHz input !
Obviously in frog land I will never find one, so hopefully will find one in Europe somewhere, or on Ebay US if shipping is reasonable. Sometimes it is.
Both the Schlumberger and the Metrix have an interesting and surprising (to me at least !) printer port at the back !!! Yes, a printer... in something that does not even have a micro in it, how can that be... glad I have the manual for both of these instruments, I have all the technical detail about it.
Well most of you probably know what it is, I guess, but I didn't so I was quite surprised to see this ! Before the advent of GPIB , manufacturers had found this clever way of outputting the measured value so it can be printed or recorded on some purpose made peripheral. Basically what they did was run the BCD outputs of the various counters to the back, and add some control signals so that the peripheral knows when to sample/record the BCD outputs. In the case of a counter, it's easy, you just use the gate trigger signal...
Obviously you need quite a large number of pins, 4 BCD lines for each and every nixie tube, plus one or more control signals, plus ground.
So in the 5 digit Schlumberger this all fits in a DB 25 connector, but in the 8 digit Metrix, they had to use a DB 50 plug ! These are not so common place...
They both use different control signals too. So clearly there was no standard describing this interface back then...
Anyway, the Metrix is compact, has good performance, so I decided to actually use it as my primary counter, rather than having it gathering dust. I will see for a more modern counter later, when the need arises and money permits !
It has a nice internal design, with boards plugging into gold plated connectors, which all look like new and no doubt helped with reliability over the years...
It does need a tiny bit of "restoration" though : as you can see from the pictures, there is a knob which is not original and looks out of place and really uglifies ( "beautifies" does exist, so why not "uglifies" ?! LOL ! ) the front panel ! That red capped black knob toward the left. Brr... I need to find an original knob ! not an easy task though !
I love this Metrix, so I thought I would design a little interface/Adapter that I could stuff on the "printer" port at the back, so I could do some data logging/experiments. Shouldn't be too complicated, I want to start work on this pretty soon and hopefully have something working by year end.
Obviously I might as well try to make it flexible enough to be used on the Schlumberger too, or any future instrument (not just counters) of this era that I might acquire in the future. Well, I mean electrical compatibility... mechanically obviously I would still need to make a little adapter since the counters don't use the same size connectors.
Anyway, time to shut up and attach some pics ! First the Schlumberger then the Metrix.