Some sleep and I am functional again ! So let's see what was in that box
Grab a pint of tea and a couple packets of your favorite biscuits
It's....a nice boat anchor !
Well it's not that heavy.. 17kg according to the manual, though I don't know it's that dry weight or not...
I can't afford to import a fancy HP 8 nixie counter, probably never will, but I found the next best thing ! A French equivalent... a Ferisol type HA300B.
'60s design, full width, looking rugged and indestructible, all discrete transistor design, 50MHz (given for 51MHz actually... marketing at play I guess...), 8 Nixie tubes, a main frame with a plug-in on the right side, and a ton of plug-in boards inside.
It is just like the old HP... but it's a Ferisol. Actually it means more to me, begin a defunct French company, so quite exotic and rare of course, being a local product, and such low volume, compared to a "mundane" easy to get (just click 'Buy' on Ebay and pay the money). So preserving this piece is even more essential I find, and I am that much more happy to have it.
I got it purely out of luck : it was NOT advertised on the usual French site, leboncoin.fr . So I should not have been aware of it being for sale.... it was advertised in a small niche French website devoted to Amateur Radio nuts.
https://radioamateur.org/ An old friend of mine used to be a HAM and still frequents this web site somehow, so the other day he sent me an e-mail to inform me that this counter was for sale
Seller wanted 120 Euros for it and local pickup only. I said no way. Said he would not go below 100 Euros no matter what. Then I said OK but I live 350kms / 4hours drive from you, so that's a lot of driving and I can't drive long distances anymore, right leg says no. Plus of course the cost of the trip is prohibitive. So I said well if I am to make the trip and pay for it, at the very least I want to make sure the thing works, because your picture only shows all zeros on the display... please feed it with a signal and get some real numbers to display on all 8 nixies. He did better than this : he spontaneously offered to make a little video of it ! At last someone living in the modern age, I was stunned...
His video revealed problems with the boards for Nixes 3, 7 and 8 (counting from the left), so he accepted to lower the price down to 80 Euros. Then I worked him a bit more and he eventually accepted to ship to me, yeah ! Much cheaper and no crazy long painful driving to do ! Also, comes with an extra plugin, and a couple original printed manuals. User manual and Service manual. This counter was now becoming more of a good deal, so I pulled the trigger. I am glad I did, loving this thing.
It survived the shipping, despite zero padding/protection on left/right/bottom sides. But the front panel and rear panel were adequately protected, plus the big handle bars on the sides (there even ones on the BACK somehow...) helped too I guess. The handles at the back are a bit bent inwards but it looks to me like it was pre-existing, not due to shipping. Not too fussed about it anyway.
DOCUMENTATIONManuals : a thing of beauty... Tektronix Quality or even better in the theory of operation section, with cool graphs and some math/equations/calculus... they certainly don't consider their usersd dumb like companies do nowadays. 200 pages thick, no less, and all in thick glossy paper. Parts list, exploded views, a nice fold out for each and every numerous boards in the thing, giving full schematic, board view/layout, and no shortage of waveforms for debugging. Extremely sweet. Only thing is that all the pages are loose, the binding plastic thing is no longer there... will get one ASAP.
The schematics uses a funny symbol for trannies ! Just like my Rochar (also french) counter the other day, but a different oe still ! The one Ferisol uses looks like.. a trim pot !
See for yourself...
I guess it males kinda sense... a variable resistor lets you adjust/control current flowing through it... just like you can do with a transistor. So I will give them that...
The user manual has some documentation with it, I mean specific to that counter : a 8 page test report from the factory, checking that all functions are OK, and a thing of beauty : a 5 page foldout, on graph paper, where they measured/plotted the performance of the crystal oscillator (1MHz no 10, and huge.. 10+ cl high, 5x5 on the sides) !! They recorded the frequency over 26 hours, taking a measurement every 15 minutes.
Counter has a plaque on its side. Says it was owned by the French Army, Telecommunications Dept. , dated December 1970. The factory test report is dated earlier than that though, September 1968.
PLUG-INSCame fitted with the default plugin : type HAL300B.
It's the basic plugin full of void inside. Just a pot to adjust sensitivity, a selector to choose from a range of input signal voltage levels, and a couple BNC sockets to chose either DC or AC coupling.
That said, it does the job so...
The extra / bonus plug-in is a type HAF 600B, a "Frequency converter". Pics below. No idea what that does. Looks similar to the HP counter part. Has a huge knob to select a frequency thing up to 500MHz or so, and a galvanometer for god knows what. Maybe I cna listen to FM radio with it
My best guess is, it's some kind of down converter of sorts to extend the frequency range of the counter.. but what it does exactly, how to use it, I don't know. hopefully I can find a manual for it on the web. If not, will go grab the manual for the HP equivalent, to at least understand the general concept, then figure out the specifics of my particular plugin...
Inside, not much electronics to speak of... a small board hidden on one side, hidden under a cover/shield. But 95% of the plug-in is mechanical stuff.... mostly a big metzallic "cavity" (like my old HP 500MHZ VHF oscillator), driven with a whole bunch of gears and cogs. Lots of "patina" on all that metal, but no rust, so I am not too fussed.. probably works fine I bet. I guess a good oiling of the gears could not hurt...
Mocking mechanism : as heavy duty as one could possibly imagine : a huge chunky 'U' shape bar, loaded at the back with a stiff spring. You press firmly downward, then at the time you pull on the bar and the plug-ins comes out. It does inspire a lot of confidence... no shitty small plastic part to break in this thing, no worries there ! Will probably still work in 200 years time !
CONDITIONOUTSIDE : need a bit of a cosmetic restoration but nothing dramatic. A couple dents under the bottom edge of the display, on the left, but nothing dramatic. Other than that :
- Top cover : a sticker to remove + lots of black marker writings on it. Not too hopeful here, will need a respray. Not that big a deal anyway.
- Bottom cover : rear edge is weird. It's all dark brown, as if it badly overheated or something... which does not make any sense. Don't know what happened there... but again a respray will fix it.
- Front panel : very filthy so needs a good clean, but should come out very decent I think, not worried. Bright work is very dull so will need some buffing/polishing : toggle siwtches, push-button, BNC sockets, binding post for Ground, bulb caps... The big handle bars on the sides look fine though.
INSIDE : Looks like new. No dust. All wafer switches are like new, gold plated, shiny, next to zero wear. Quite a contrast with all my Tek scopes where the wafer switches are all dark/ black, horrible.
All boards have conformal coating on them, so preserved they have been... will make troubleshooting a pain though. Is there a magical chemical product out there, specifically designed/formulated to dissolve that coating, efficiently and quickly ? Does such a magical product exist ?? If it does, please speak up....
Display : the Nixie tubes are not aligned properly, at all. The driver boards are, though, help in place securely with a bracket. so I guess it's just the tubes themselves that are not sockets properly, so hopefully should be easy to fix
MISCELLANEOUSPower socket : has the weirdest socket I have ever seen, for sure ! It's not even a "consumer" type socket ! Plus, it's PROTRUDING instead of being recessed ! Might be why they added handle bars at the back as well.. to protect this connector somewhat. See picture below. It's round, protruding a lot, and has a bayonet style locking mechanism. Yes, I told you it was weird, didn't I...
Luckily the seller supplied the power cord to go with it !!!
The service manual told me all about this connector, luckily : it's made by some company by the name of " SOCAPEX ", whoever they are. Model number for the socket is FFC23AL and for the plug it's EM23AL.
Has printer port at the back. I mean of course it's not for a "Printer".. it's the data recorder output, BUT unlike my other old counters featuring such an output, it does NOT use a Sub-D connector (25 or 50 pins depending on model), but a an ACTUAL printer connector : the usual Centronics printer port !
Now I am glad I kept that box full of 2 dozen old printer cables !!
Has an input for external frequency ref, so once I get a 10MHz ref I can hook the counter to it and make as accurate as any modern gear, which is cool. Of course would need to divide the ref by 10 first, since the counter uses 1MHz not 10MHz.
ELECTRICAL CONDITIONGenerally speaking, it appears to be fully functional, and all knows turn freely. No need to Deoxit or lubricate anything. As mentioned above it's all gold plated and looking shiny as new.
Using my HP 3200B VHF oscillator I was able to test it in a controlled manner, I love this thing, ideal to test the B/W on all my old counters and scopes.
As I said Ferisol specs this counters at 51MHz, but I was able to push it no problem up to 68MHz !
In the PSU section, there is a small board that carries a row of 3 small bridge rectifiers, that look very modern to be honest, but the board also looks very factory so... maybe these bridges were indeed available in the late '60's go figure. At any rate, I noticed the one of the 3 bridges, the middle one, suffered a dramatic event... see pic. All 4 traces going to it, on the top side, badly overheated ! Some tracks are gone, some pads are half gone or missing. Solder joints are missing, no solder to be seen .... but don't panic : on the top side, these joints were not connected to anything anyway. All 4 legs of the bridge are actually connected on the bottom side, and on that side everything is looking OK, so it's functional, no worries, it's been repaired clearly. So clearly someone worked on this counter before, which is quite unexpected for a counter that only 65 years old ! I am shocked !
Might still want to clean that mess up a bit though, of course !
So, the only real electrical problems we have on this counter, as mentioned at the start of this post, are to do with 3 of the Nixie displays, that misbehave. : number 3, 7 ans 8 respectively, starting from the left side of the display. #3 is the one for which the fault is the easiest to characterize, but for #7 and #8 I had to play with the counter for a good hour to figure out a pattern and characterize it well enough that I could reproduce and quantify the fault 100%. They both exhibit the same symptoms. ## is a bit different though.
So here goes :
Tube #3 :The symptoms are a bit different depending on whether or not you are latching the display.
- UN-latched (i.e. you can see the counter counting while it's taking its measurement) : digits '4' and '5' fail to display, display is off, nothing to be seen, not even dim/faint.
- Latched : When it gets to displaying a '4', instead it shows a BLINKING '0'. Looking more closely, this is due to : during the counting (which you can't see since it's latched), the Nixie uis turned OFF, then when the counter has finished counting and briefly displays the result, tube comes back to lie again and displays '0' instead of '4'. So you get cycle of blank for a while, then a brif '0', then blanck again.. so it looks like a blinking '0'.
Same exact problem when it needs to display a '5'. Except this time instead of showing a blinking '0', it shows a blinking '1'
Tube #8 (LSD) :Sometimes it is stuck on displaying a '0' and sometimes it turns off altogether, like fuck you leave me alone and go somewhere else ! Not nice...
After a lot of playing around, I eventually found a pattern : its behaviour seems to be frequency dependent, it must have trouble keeping up at higher speeds.
Problem shows up only a long gate opening times : 1s and 10s, which males sense I guess, it adds up, as that when that decade board will be subjected to the highest clock rates.
So, I established that :
- Up to a couple 100kHz, it works fine.
- When you get around 300kHz, it starts to misbehave and is more and more inclined to get stuck to displaying a solid '0'
- Push it a bit higher still, not by much, say 400kHz or so, and then it worsens and the tube turns off altogether, end of show...
Tube #7 :Same behaviour but a frequencies about 10 times higher, 5 or 6 MHz, which makes perfect sense since this tube sees a 1/10 of the Frequency of tube #8.
This is all 100% reproducible, repeatable at will.... meaning I guess I stand at least some chance of diagnosing it, and hopefully fixing it if parts, or substitutes for the Germanium trannies, are available...
So I will need to make extender cards on Kicad, cool, some exercise...
While I am at it I might as well make 2 more cards, (there are 3 different sizes of connectors in that chassis), so I can potentially work on any board in this counter, not just the Nixie boards.
There are no less than 27 plugins boards in this counter....
Some piccies now... obviously will need to spread them over several posts and inevitably people will post in between the pics, ah well, can't avoid that, so please give me a few minutes to upload and post all the pics...
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