Lets see your Nixie Tube equipment

[bitseeker]

Funny you should mention that. I was thinking along those lines as well. It would be a non-intrusive way to keep these counters useful. The 5216 I have is a 12.5 MHz counter, so a /10 pre-scaler would make it a nice 125 MHz device.

[Enigma-man]

@bitseeker:
Glad you liked my 5221A.  The prescaler would be easy to construct.  The only downside is powering the thing with an external power supply.
I suppose one could take +5V from the unit itself and run the wire through a perforation on the bottom plate.

I wonder why the previous owner of Cubdriver's 5221 would modify it to accommodate banana plugs when all he had to do was hook up the jacks to
a piece of BNC cable.
It still serves the purpose and saves time by not having to modify/bastardize the unit.

[bitseeker]

I'd be very interested in making a prescaler. Although I have an idea how counters operate, I don't have in-depth knowledge of their design and operation. Thus, mine will serve an educational function in addition to bringing them back to full operation and looking cool on my bench.

On the 5221 and 5216, pin 3 of the digital recorder/printer connector provides 5V and pin 1 is ground. However, I haven't looked into the schematics to see if it could actually take a load. It's intended to be a 5V reference for the data lines. Nevertheless, if you took power from elsewhere inside the unit, you might be able to make use of the space around the card edge connector to run the wires to the prescaler. I'd be fine with just putting a DC jack on the prescaler or using a bench supply (got plenty of those).

Regarding the banana plug modification, it's also odd that a simple BNC-to-banana adapter wasn't used. Although that counter sounds familiar, I don't recall how good of a job the owner did. Hopefully, it doesn't look bad.

[Enigma-man]

I think the prescaler for my 5221A would be a waste of time.  With only 4 digits and no over range indicator, there's no way to
tell what the actual frequency is.  When 1MHz is applied all I get is the rightmost digit showing a zero. 
I think my unit may have seen use as an event counter of some sort.  When the switch is in "OPEN" position, it counts up until 9999 then goes back to zero.
Not a big deal for me and the 5221A won't see a lot of use unless I can add two more digits in future. It's more of a show and tell item.
It works as a frequency counter in a limited capacity.

However, I will breadboard a prescaler then hand draw a pc board if you want one.  It's not a complicated piece of hardware. 

I have close to 100 RCA CA3179 1.25GHz prescaler IC's.  The only drawback is that they divide the VHF signal by 64 and the UHF by 256.
The timebase of the counter would have to be modified to see the true frequency.  A one or ten Hertz timebase would show the input signal
as the result of the input frequency divided by 64 or 256.  That's why I never used any of them.
700MHz would show 10937500 on the counter.
A calculator would give you the proper result 109375 X 64 = 700,000,000
If I was making a kit, I would toss in a dollar store  $2 calculator as  an "Auxillary Display Device"... 
Getting ahead of myself here.

[bitseeker]

With only 4 digits and no over range indicator, there's no way to tell what the actual frequency is.

I see. So that might be why the B version has five digits standard.

Not a big deal for me and the 5221A won't see a lot of use unless I can add two more digits in future. It's more of a show and tell item.

As a show item, it's certainly easier to live with on the desk than a full rack width counter.

However, I will breadboard a prescaler then hand draw a pc board if you want one.  It's not a complicated piece of hardware.

Thanks, very kind of you.

I have close to 100 RCA CA3179 1.25GHz prescaler IC's.  The only drawback is that they divide the VHF signal by 64 and the UHF by 256.
The timebase of the counter would have to be modified to see the true frequency.  A one or ten Hertz timebase would show the input signal
as the result of the input frequency divided by 64 or 256.  That's why I never used any of them.

Yeah, that sounds like a pain.

If I was making a kit, I would toss in a dollar store  $2 calculator as  an "Auxillary Display Device"... 

LOL! I'd probably hook up an Arduino to the digital recorder port and have it do the conversion for proper display. Of course, one could also do the division with a dedicated circuit.

[Enigma-man]

More seven segment Panaplex  gas discharge displays...
The small ones are made by Sperry.  The two digit ones are SP-336 and three digit are EX-337.
Sphere was asking $49 each for the three digit  and $15 for the two digit.  The Beckman 1.5" are
shown for size comparison.
Two Beckman DD-700 7 seven segment driver chips are on the foam as is a 1.25GHz RCA CA3179 chip. (Not relevant)
Last but not least, the first IC I ever bought... A TI SN 7450P in a ceramic package with metal top dated 6626.
I have quite a collection of vintage CPU's and memory devices as well.
I have 25 Sperry flat pack RTL uL925's in an unopened package dated 6520.
That's for another thread.
I forgot to mention that the little red rectangle is a three digit multiplexed LED display. The digits are barely more than  1/10 inch high.
Man, that is small...

[bitseeker]

What are the triangles and squares that I see below the digits on many of these Panaplex displays?

[richfiles]

I think the triangles are intended to be decimals/commas, and the square bits at the bottom are likely part of the metal of the electrode... I can never remember if it's the anode... I wanna say the segments are the cathodes... Gah! I can never remember!   

[Enigma-man]

Yes, the triangles are decimals.  The small Sperry displays only had decimals while the bigger Beckman displays could be used in clocks since they had
the colon as well as a decimal and bar to make a comma.  I'll hook up the big ones to a voltage source as they are already in sockets and on the pc board.
I don't have any sockets for the small ones but I'll see what I can do and post some pix.
Actually, the small ones were used in my capacitance meter a few posts back so you could see them there.

[Gyro]

Yes, the triangles in line with the bottom edge of the digits are decimals. The triangle down at the bottom (between the rectangles) is a 'keep-alive' electrode; it is constantly driven at low current when the displays are multiplexed. This provides a ready source of ionization to ensure that the display can re-light quickly.

The rectangular structures are spring contacts that make contact with the front glass. The anodes are actually a conductive coating on the inside of the front glass, if you look in the right light you can see the conductive areas, one for each digit. Having the anodes on the front glass means that the glow is concentrated on the front of the cathode segments, making them sharper (unlike nixies, there the various cathode shapes aren't terribly sure where the nearest bit of anode actually is  ).

The circular ring around the leftmost rectangular spring is the getter, for mopping up unwelcome gasses.

[Enigma-man]

Here is a Nixie power supply I made to power the Beckman's.   It is a 555 driving an IRF740 Mosfet. The coil is a Coilcraft
100uH surface mount inductor.  The other power tab is a fast recovery diode rated at 1200V and 8 amp.  A bit on the overkill
scale but who cares ?  I have some and might as well use 'em.  It put out 192 volts when I first turned it on and haven't adjusted
the voltage yet.  The Beckman's take more current than Nixies do.  I found some application notes from Beckman that I still kept
after all these years. The app note says 5mA.
The display isn't as bright as it appears.  It's the camera's fault.
The Eldorado shows the voltage.  Now to make something with the Beckman's...

[bitseeker]

Here is a Nixie power supply I made to power the Beckman's.

At first glance, I thought you built a power supply with a Nixie tube display. The thumbnail of the Eldorado meter looked like it was the power supply's front panel and display.

[Enigma-man]

Today's show and tell is a Fairchild 7050 3.5 digit meter with National NL-848 style Nixies.
It's in pretty good shape for something made back in 1967 according to datecodes inside.
Some minor issues resulting from shitty repair attempts like damaging the pc board, solder pads missing,
but nothing too serious.  It needed minor cleaning in and out.  The unit is still reasonably well calibrated.
When I hooked up my AD688 10V reference, it showed +10.02 volts. Not bad, but it was adjusted to +10.00V
I found a service manual for it which reads Systron Donner Model 7050.  It's exactly the same so it looks like
Fairchild made them for SD.  This is all RTL logic, some Fairchild types as as well as the old ul9XX series. Round can
types for decade counters. 
It's pretty compact for what it does. Everything is on one pc board.
The plus/minus and the 1 indicator are standard NE-2 bulbs shining through a square piece of clear plastic.

Well, that's it for now.

[Enigma-man]

A few pix of the Fairchild 7050 circuit board after minor cleaning and isopropyl scrub on other
side of board.
In my opinion, this was an underrated piece of gear.  It is very stable and surprisingly accurate and is way more stable than the Eldorado 1820A.
The service manual shows accuracy claims of .1% from 0.000 to 1000V...  Not too shabby. 
I let it run all night and it still showed +10.00 volts this morning.
It gets a  for looks.   

[bitseeker]

It's doesn't look that bad -- it's got Nixies!

[bitseeker]

Here are my HP 5216A, 12.5 MHz counters. The one on top is older, having an oval-shaped power socket, whereas the lower one has an IEC socket. The top one also didn't want to wake up today, so it gets its photo taken while napping.

Suffice it to say, they both need an overhaul, but since that may be a while I figured I'd at least share a photo for the thread.

[Enigma-man]

I hate you...        Your two counters have a total of fourteen Nixies, while my 5221A has a measly, paltry four tubes, upside down rare types.

Good to see one working and they are both in pretty good shape.  Hopefully the napping one doesn't have a logic problem.
Finding the problem would be easier than finding a replacement RTL chip unless you have a donor.

[bitseeker]

It took quite some time to find these in good cosmetic condition. They aren't that prevalent to begin with, regardless of condition. The Nixies are upside-down, though, just like yours. All the HP counters of this era have very similar parts, including the proprietary driver and decoder ICs.

I suspect that the primary problem with mine is in the power supply, in particular, and all the ecaps, in general, since one doesn't always wake up and both, when they are awake, count and/or gate intermittently. Some of the digits seem a bit flaky, though.

If there are failing ICs, I can either make one of the counters a donor (hence I have two of them), replace with standard ICs forgoing the blanking feature, or make a daughter board to restore the blanking functionality using standard logic ICs.

[Cubdriver]

My 5216A has begun its eastward journey; it should be here in a few days.     Hopefully the gating problem it has won't be a show stopper.  And thanks to bitseeker for pointing it out and not bidding against me!  Now we can collaborate on fixing them.

The pair of boxes holding ~200 pounds worth of gear I shipped home from CA last week arrived today too, hopefully unscathed.  (If it is scathed, I've no one to blame but myself as I'm the one who packed it.) They contain more nixie goodies for the ever growing pile-o-projects.

The first has a Dymec 2401C integrating voltmeter and a 2410B AC/Ohms converter (unfortunately the 2401 lacks a couple of boards needed to interface with the converter, but perhaps I can cobble something together as a substitute).  The second has the 2402A DVM and 5360A Computing Counter I snared at the surplus place last December on the trip when I got the plague and didn't manage to ship anything home.  They'd been waiting patiently on the shelf at the office out there since then. After searching since December I finally found a copy of the 2402A manual that was being sold by someone who didn't think it was printed in platinum ink on gold leaf pages and want insane money for it.  There are some pics of the 2401C and 5360A taken out in CA on the SmugMug site, but I don't think any of the 2402A are up.

Now if I can just stay away from ebuy (there are a couple of more nixie, VFD and panaplex meters enroute, too) and swap meets and surplus dealers for a few years...  And maybe reinforce the foundation here before the house starts sinking into the ground.

-Pat

[bitseeker]

Now if I can just stay away from ebuy (there are a couple of more nixie, VFD and panaplex meters enroute, too) and swap meets and surplus dealers for a few years...

OK, Pat. I'll do my best to avoid tempting you going forward.

Enigma-man will have to rescue the next 5216A from the landfill. Maybe he'll stop hating me, then.

[Enigma-man]

I'll call McFly and see if he's free on Friday so we can again take the DeLorean back to '69 or '70, hijack another shipment destined for the
local HP office and snag you a brand spankin' new 5216A...

From the photo, the top unit looks like it has standard Nixies. Must be due to a reflection.
You would have to change your power supply to accommodate standard 74 series devices and rig up a level converter in between .  RTL needs 3.6V.
I am assuming both have RTL devices or does it have a mixture of standard 74 series and HP's version of TTL ?

[Cubdriver]

Now if I can just stay away from ebuy (there are a couple of more nixie, VFD and panaplex meters enroute, too) and swap meets and surplus dealers for a few years...

OK, Pat. I'll do my best to avoid tempting you going forward.

Enigma-man will have to rescue the next 5216A from the landfill. Maybe he'll stop hating me, then.

   It won't do any good.  It would have showed up in my watching feed even if you hadn't mentioned it.  What I should do (but won't, of course!) is turn off e-mail notifications. 

-Pat

[bitseeker]

From the photo, the top unit looks like it has standard Nixies. Must be due to a reflection.

Yes, those tubes do seem to be oriented the other way. However, look above the tubes. You can see the edge of the PCB that they're mounted onto.

I am assuming both have RTL devices or does it have a mixture of standard 74 series and HP's version of TTL ?

I haven't gotten that deep into the details of these devices. Perhaps Pat knows.

[Cubdriver]

I'll call McFly and see if he's free on Friday so we can again take the DeLorean back to '69 or '70, hijack another shipment destined for the
local HP office and snag you a brand spankin' new 5216A...

From the photo, the top unit looks like it has standard Nixies. Must be due to a reflection.
You would have to change your power supply to accommodate standard 74 series devices and rig up a level converter in between .  RTL needs 3.6V.
I am assuming both have RTL devices or does it have a mixture of standard 74 series and HP's version of TTL ?

Nope - they're the HP 1970-0025/Burroughs B5560 'Bat' tubes like those in the 5221/5231s.

-Pat

[bitseeker]

What I should do (but won't, of course!) is turn off e-mail notifications. 

Yeah, that wouldn't help in my case. I found that I see new items faster than eBay can email me, so I don't even bother turning on those notifications anymore.