Something for the tube/nixie making people?

[Dekatron42]

Have a look at auction: http://www.ebay.co.uk/itm/SK-Science-Kit-Electron-Beam-Tube-Lot-of-29-/300955680420?pt=LH_DefaultDomain_0&hash=item46125b3ea4

 

I have no connection to this auction, just stumbled across it.

 

/Martin

[greg...@hotmail.com]

I've always been curious what level of glassblowing skills and cost/quality of vacuum equipment one would need to make their own tubes.

I had given some thought to attempt to make my own nixie tubes and other ionized gas devices, then concluded it would take me several years and several thousand US $ to make anything that would have a decent lifetime. 

[NeonJohn]

I blow glass and make neon as hobbies and am the chief engineer at
Fluxeon which makes induction heaters, useful for heating the internals
of a vacuum tube to outgas them so maybe I can throw in here a bit.

The first thing you'd need to do is pay to have a very thorough
engineering analysis made of an existing tube known to have a long live.
You'd want to learn, among other things, the type of glass used, the
type of glass/metal seal used, the atmosphere (composition and pressure)
inside the tube, the chemistry of the electrode metals and their surface
treatment. The last part is probably the most important part.

As far as the glass blowing goes, it's not really practical to do this
by hand. Even though some people on this list are playing around with
pinch seal, flying lead tubes, those aren't going anywhere, IMO. You'll
need an actual multi-pin glass base that is pre-manufactured and is
welded to the envelope as one of the final steps in manufacturing.

If you watch some of the u-toob videos of vacuum tubes being made, you
can see how the base is made. Pins made of the proper transition metal
are inserted into a metal mold. A gob of molten glass is deposited into
the center of the mold and the mating half is pressed down, forcing the
glass around the pins and into all the nooks and crannies of the mold.

The temperature of the mold, the temperature of the glass, the quantity
of glass in the gob, cooling time before ejection and a bunch of other
things in the process that have to be tuned and optimized.

Many years ago I worked for an engineer named Ed Kay who was the chief
engineer at the Tung-Sol tube plant in NJ before it closed. I was
interested in ham radio and a little bit interested in tubes so we
talked tube manufacturing a lot. I wasn't yet interested in glass
blowing so I didn't spend too much time on the subject of the glass
manufacture. I did get some knowledge from him, however.

Making the envelope for a side-view Nixie is fairly easy using glass
tubing and scientific glass blowing techniques, though you'd want to
automate that too, if you plan on making very many tubes, something
you'd have to do to justify setting up and running the base making
machinery.

Making the envelope for the non-round top view tube would be quite
complex. I'm pretty sure those were deep drawn similar to the way
beverage cans are made but I've never seen it done. I'd probably focus
first on the round side view tube.

In terms of vacuum, it depends on the production rate you have in mind.
For tiny volume, hand made tubes, you'd need a pretty high vacuum - in
diffusion or turbomolecular pump range - and an oven to outgas the
electrodes.

For high speed production, the tube, still hot from having the base
welded on would go onto the vacuum manifold where vacuum is applied.
Simultaneously, the internals are heated with an induction heater to
outgas the electrodes without requiring a high vacuum. A getter may
also be used. The vacuum requirement is modest since the tube is
already hot and the electrodes are heated red hot.

John

--
John DeArmond
Tellico Plains, Occupied TN
http://www.fluxeon.com <-- THE source for induction heaters
http://www.neon-john.com <-- email from here
http://www.johndearmond.com <-- Best damned Blog on the net
PGP key: wwwkeys.pgp.net: BCB68D77

[Dalibor Farný]

Hi, You are right.. By end of this year, it will be two years of
everyday work (3hrs/day in average) I spent struggling to bring back
the nixie tube technology. I lost clue on spent cash at $10k, and,
believe me, I think twice before spending every dollar ;-)

But I overcome most of the problems and learned a lot, I think I will
be able to produce real longlife tubes.. I attached current photo of
my workshop.. I am able to bend the metal parts and weld it all
together, even with a getter pill. I am now able to work with glass on
a glass lathe with several torches, make 11-pin vacuum tight seal (not
flat disc yet, only the pinch used in audio tubes) and test it on
helium leak detector for leaks. I am able to make envelope for it with
evacuation tube and seal it all together. I am able to evacuate it,
pump it below 10-4 torr, bake it out in the oven, fill it with
neon/argon mixture and tip it off. I already made two sample tubes,
one is 6 months old and still works with the same parameters as it was
originally measured.

I am now waiting for glass tubing of right diameter to make envelopes
and some minor things (will be in two weeks), I will then produce a
series of "lab samples" which I am going to offer on eBay from $1 ;-)

The worst thing is that even You had millions, it would be very
difficult to push the development ahead. Most of the technology is
forgotten, there are only general information in books or articles on
eBay, many things You have to find out yourself. In time when tubes
were mass produced, there were companies that had thick catalogues
with parts and material that You could order for cheap. For example a
special steel metal sheet plated with aluminum that was heated and
annealed in vacuum reacting with steel and making matte grey surface.
That metal sheet was used in almost every vacuum tube, it was produced
in tons.. It is not possible to get it now and if You want a company
to make it for You, You have to buy a ton for tens of thousands
euros.. This sheet was used for the backplate in nixie tubes - it
eliminates reflections from glowing numbers.

I hope the attachment is not too big.. 400kb..

Dalibor
http://dalibor.farny.cz

2013/8/28 greg...@hotmail.com <greg...@hotmail.com>:

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http://dalibor.farny.cz

[John Rehwinkel]

> I am now waiting for glass tubing of right diameter to make envelopes
> and some minor things (will be in two weeks), I will then produce a
> series of "lab samples" which I am going to offer on eBay from $1 ;-)

I'll be really interested in bidding on these!

> That metal sheet was used in almost every vacuum tube, it was produced
> in tons.. It is not possible to get it now and if You want a company
> to make it for You, You have to buy a ton for tens of thousands
> euros..

Like this?

http://www.almetals.com/excess_detail.aspx?Tag=56527W&des=Al%20Clad%20Feran%205/90/5%20DDQ&type=Clad&gauge=0.0071

- John

[Dalibor Farný]

2013/8/28 NeonJohn <j...@neon-john.com>:

> I blow glass and make neon as hobbies and am the chief engineer at
> Fluxeon which makes induction heaters, useful for heating the internals
> of a vacuum tube to outgas them so maybe I can throw in here a bit.

Great info, I just need one RF heater ;-)

>
> The first thing you'd need to do is pay to have a very thorough
> engineering analysis made of an existing tube known to have a long live.
> You'd want to learn, among other things, the type of glass used

- , mostly lead glass as this achieve high viscosity at low
temperatures, hard to find and impractical for hand making (tends to
crack.)

, the
> type of glass/metal seal used,

- Dumet wire / lead glass, the dumet wire has a Ni-Fe core, it is
plated with thin layer of copper and borated.. It makes great seal at
low temperatures with soft glasses, and it is almost impossible to
make bad seal with it ;-)

the atmosphere (composition and pressure)

around 0.1 - 0.001% of Argon with Neon, total pressure around 20torr
and higher, lower pressure means that numbers becomes fuzzy. In latest
tubes is also a mercury present, the amount is not critical. Only
thing I dont know is whether the mercury has an impact on breakdown
voltage..

> inside the tube, the chemistry of the electrode metals and their surface

only low-carbon stainless steel or nickel, nothing special (no
materials with high vapour pressure below 500C).

> treatment. The last part is probably the most important part.
>
> As far as the glass blowing goes, it's not really practical to do this
> by hand. Even though some people on this list are playing around with
> pinch seal, flying lead tubes, those aren't going anywhere, IMO. You'll
> need an actual multi-pin glass base that is pre-manufactured and is
> welded to the envelope as one of the final steps in manufacturing.

Why we (pinch seal makers) are not going anywhere? Look to Rodan CD47,
there is also pinch seal.. But it would be definitely better to have
disc shaped stems.. There are companies that produce them, but for
high prices. I will definitely try to build a machine for making flat
stems, but that is far future..

>
> If you watch some of the u-toob videos of vacuum tubes being made, you
> can see how the base is made. Pins made of the proper transition metal
> are inserted into a metal mold. A gob of molten glass is deposited into
> the center of the mold and the mating half is pressed down, forcing the
> glass around the pins and into all the nooks and crannies of the mold.
>
> The temperature of the mold, the temperature of the glass, the quantity
> of glass in the gob, cooling time before ejection and a bunch of other
> things in the process that have to be tuned and optimized.
>
> Many years ago I worked for an engineer named Ed Kay who was the chief
> engineer at the Tung-Sol tube plant in NJ before it closed.

Great, I read an article about them recently..

I was
> interested in ham radio and a little bit interested in tubes so we
> talked tube manufacturing a lot. I wasn't yet interested in glass
> blowing so I didn't spend too much time on the subject of the glass
> manufacture. I did get some knowledge from him, however.
>
> Making the envelope for a side-view Nixie is fairly easy using glass
> tubing and scientific glass blowing techniques, though you'd want to
> automate that too, if you plan on making very many tubes, something
> you'd have to do to justify setting up and running the base making
> machinery.
>
> Making the envelope for the non-round top view tube would be quite
> complex. I'm pretty sure those were deep drawn similar to the way
> beverage cans are made but I've never seen it done. I'd probably focus
> first on the round side view tube.

http://youtu.be/8n4WVRKkmww?t=2m12s

>
> In terms of vacuum, it depends on the production rate you have in mind.
> For tiny volume, hand made tubes, you'd need a pretty high vacuum - in
> diffusion or turbomolecular pump range - and an oven to outgas the
> electrodes.
>
> For high speed production, the tube, still hot from having the base
> welded on would go onto the vacuum manifold where vacuum is applied.
> Simultaneously, the internals are heated with an induction heater to
> outgas the electrodes without requiring a high vacuum. A getter may
> also be used. The vacuum requirement is modest since the tube is
> already hot and the electrodes are heated red hot.

I think that there wont be demand for mass producing nixie tubes
anymore.. I will focus on hand making tubes that are absolutely unique
and manufactured precisely to smallest detail, making own clocks in
the future. This is the only way I see..

Dalibor

>
> John
>
>
> On 08/28/2013 12:15 PM, greg...@hotmail.com wrote:
>> I've always been curious what level of glassblowing skills and cost/quality
>> of vacuum equipment one would need to make their own tubes.
>>
>> I had given some thought to attempt to make my own nixie tubes and other
>> ionized gas devices, then concluded it would take me several years and
>> several thousand US $ to make anything that would have a decent lifetime.
>>
>
> --
> John DeArmond
> Tellico Plains, Occupied TN
> http://www.fluxeon.com <-- THE source for induction heaters
> http://www.neon-john.com <-- email from here
> http://www.johndearmond.com <-- Best damned Blog on the net
> PGP key: wwwkeys.pgp.net: BCB68D77
>

> --
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[NeonJohn]

On 08/28/2013 01:03 PM, Dalibor Farný wrote:

> I hope the attachment is not too big.. 400kb..

Nice. Gee, uh, I thought it was against the law or something to have a
shop that clean and neat. I'm afraid to post photos of my shops, lest
people confuse them with fractals or something :-)

John

[Dalibor Farný]

Thanks!

That metal might really be the one we are looking for, I will check it!

Dalibor

2013/8/28 John Rehwinkel <jre...@mac.com>:

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[NeonJohn]

On 08/28/2013 01:28 PM, Dalibor Farný wrote:
> 2013/8/28 NeonJohn <j...@neon-john.com>:
>> I blow glass and make neon as hobbies and am the chief engineer at
>> Fluxeon which makes induction heaters, useful for heating the internals
>> of a vacuum tube to outgas them so maybe I can throw in here a bit.
>
> Great info, I just need one RF heater ;-)

Here's my open-source heater page.

http://www.neon-john.net/Induction/Roy/Roy.htm

If you don't have the time nor inclination to do it from scratch, here's
that same heater in kit form

http://www.fluxeon.com/Roy1200.html

> - , mostly lead glass as this achieve high viscosity at low
> temperatures, hard to find and impractical for hand making (tends to
> crack.)

I like leaded glass MUCH better than any other formulation. It's
liquidus stage is wide, requires little to no annealing and as you note,
sticks to dumet (or even just plain old copper) just fine.

The enviro-nazis have made manufacturing lead glass tube very difficult
so it's practically unavailable. Last time I heard, there's a factory
in the Czech Republic still making it.

The neon and related industries are now stuck with lead-free glass. It
has the same coefficient of expansion as lead glass and seals to dumet
but it has a much narrower liquidus range so it's significantly more
difficult to work with. Plus its melting point is high enough that it
produces copious sodium flare, requiring didydmium glasses.

In Europe, the glass is available from Tecnolux in Germany. I don't
like their glass but the one I do like (FMC) is US made and may not be
available in Europe.

> the atmosphere (composition and pressure)
> around 0.1 - 0.001% of Argon with Neon, total pressure around 20torr
> and higher, lower pressure means that numbers becomes fuzzy. In latest
> tubes is also a mercury present, the amount is not critical. Only
> thing I dont know is whether the mercury has an impact on breakdown
> voltage..

That "around" thing is the problem. I'm sure lots of research went in
to perfecting the gas mixture and pressure, something I don't think you
want to have to duplicate, thus the suggestion to have a known
long-lived one analyzed.

A wide range of pressures will "work" but the lifetime looks like an
upside-down "U" around the optimum pressure. For example, I can load a
15mm tube with anywhere from about 2 Torr to 20 Torr but the long life
point is 12 Torr for short tubes and 8 Torr for long ones.

At least with neon, the mercury does not affect the voltage drop across
the tube. The argon/neon ratio is the primary determinant.

> I think that there wont be demand for mass producing nixie tubes
> anymore.. I will focus on hand making tubes that are absolutely unique
> and manufactured precisely to smallest detail, making own clocks in
> the future. This is the only way I see..

There'll be the typical inverse price/demand curve but I bet that if the
cost of tubes could be brought down to under $5 through mass
manufacturing, there would be a large demand. Nostalga is in. Plus the
Nixie is still the easiest display technology to read.

Just my opinions, of course.

John

[Dalibor Farný]

Thats because I finished the shed a month ago, I am just moving the
stuff here ;-) Look here, thats one year old photo of my pre-previous
shop ;-)

http://dalibor.farny.cz/wp-content/uploads/2012/10/IMG_8465.jpg
http://dalibor.farny.cz/wp-content/uploads/2012/10/IMG_8469.jpg

If You want to see really clean and neat workshop, watch that:
http://youtu.be/haxtlJcjY8o ;-)

Dalibor

2013/8/28 NeonJohn <j...@neon-john.com>:

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[Dalibor Farný]

2013/8/28 NeonJohn <j...@neon-john.com>:

>
>
> On 08/28/2013 01:28 PM, Dalibor Farný wrote:
>> 2013/8/28 NeonJohn <j...@neon-john.com>:

> The enviro-nazis have made manufacturing lead glass tube very difficult
> so it's practically unavailable. Last time I heard, there's a factory
> in the Czech Republic still making it.

I know only about companies producing leaded glass for bowls and other
decorative glass.. Not tubing..

>
>> the atmosphere (composition and pressure)
>> around 0.1 - 0.001% of Argon with Neon, total pressure around 20torr
>> and higher, lower pressure means that numbers becomes fuzzy. In latest
>> tubes is also a mercury present, the amount is not critical. Only
>> thing I dont know is whether the mercury has an impact on breakdown
>> voltage..
>
> That "around" thing is the problem. I'm sure lots of research went in
> to perfecting the gas mixture and pressure, something I don't think you
> want to have to duplicate, thus the suggestion to have a known
> long-lived one analyzed.

There is detailed graph of pressure and breakdown voltage for
different NeAr mixtures, but generally everything below 1% of Ar is
good. It is in a book Weston: Cold cathode glow discharge tubes. The
higher the pressure is, the lower is velocity of the particles
bombarding the electrodes, so the lifetime is higher. This is at least
what I read. But the higher pressure also means higher breakdown
voltage, so a compromise is necessary. The main thing that influences
the lifetime is a presence of the mercury vapours inside (5.000 vs
200.000 hours), I found in one old patent that the amount of mercury
is not critical.. Ron Soyland discovered one z566m (or zm1040?) with
intact mercury capsule - they were not able to crack it during
manufacturing. We counted the volume and found that there was 2.5mg of
mercury, I would start at that amount..

anyway, thanks for info that mercury doesnt affect breakdown voltage..
I will have to experiment with mixtures..

Dalibor

>
> A wide range of pressures will "work" but the lifetime looks like an
> upside-down "U" around the optimum pressure. For example, I can load a
> 15mm tube with anywhere from about 2 Torr to 20 Torr but the long life
> point is 12 Torr for short tubes and 8 Torr for long ones.
>
> At least with neon, the mercury does not affect the voltage drop across
> the tube. The argon/neon ratio is the primary determinant.

> John
>
>
> --
> John DeArmond
> Tellico Plains, Occupied TN
> http://www.fluxeon.com <-- THE source for induction heaters
> http://www.neon-john.com <-- email from here
> http://www.johndearmond.com <-- Best damned Blog on the net
> PGP key: wwwkeys.pgp.net: BCB68D77
>

> --
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[John Rehwinkel]

> I know only about companies producing leaded glass for bowls and other
> decorative glass.. Not tubing..

There's some coming out of China, according to the rumour mill.

> I found in one old patent that the amount of mercury
> is not critical..

Right - the mercury pressure equalizes at the vapor pressure of the coolest part of the envelope, as long as you have enough.

> Ron Soyland discovered one z566m (or zm1040?) with
> intact mercury capsule - they were not able to crack it during
> manufacturing. We counted the volume and found that there was 2.5mg of
> mercury, I would start at that amount..

Right, the "enough" I referred to above doesn't require much at all. You could calculate it if you knew your total volume, the amount adsorbed on the electrodes, and the cool spot temperature range.

> anyway, thanks for info that mercury doesnt affect breakdown voltage..

Yeah, that's why mercury vapor lamps have a "carrier" gas to establish the arc.

- John

[Dalibor Farný]

Thanks, is there any source how to calculate the amount of the mercury needed? I would google it, but I am finding only "how much mercury in fish" and other encouraging stuff ;-)

2013/8/28 John Rehwinkel <jre...@mac.com>

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[John Rehwinkel]

> Thanks, is there any source how to calculate the amount of the mercury needed? I would google it, but I am finding only "how much mercury in fish" and other encouraging stuff ;-)

It gets interesting. You'll need to multiply the volume of your envelope by the partial pressure of mercury at the cool spot temperature. Then you'll have to figure out how much mercury this is.

There's a good writeup on partial pressures of mercury here:

http://www.physics.rutgers.edu/~eandrei/389/NISTIR.6643.pdf

Note that this is slightly affected by the other gases in your enclosure, by Dalton's law:

http://library.thinkquest.org/12596/dalton.html

That said, it looks like the partial pressure of mercury is around 1e-3kPa at standard temperature.

A mole of mercury vapor is 22.4 liters at standard pressure (101kPa) (ideal gas law) and weighs 200g.

Assuming you had a volume of 10cc, you'd have 10/(22.4*1000) * 1e-3/101 = 4e-9 moles. That, times
200g/mole yields 9e-7g of mercury, about 1 microgram. So that's the amount of mercury vapor it would
take to fill your 10cc volume at a cold spot temperature of "standard temperature" at equilibrium. That,
unfortunately, doesn't do you a lot of good, as you'll need excess liquid mercury to maintain equilibrium,
plus the amount of mercury required to actually adsorb to your cathodes to protect them, and get wasted
sticking to other surfaces. And these amounts utterly dominate the amount present as vapor.

As you pointed out earlier, commercial tubes seem to use on the order of 2.5mg of mercury, which is
big enough to measure out, and certainly sufficient. I've seen liquid mercury beaded up in nixie tubes,
so too much (within reason) doesn't seem to be a problem. I understanding not wanting to waste it,
but I'd just kick in 2.5mg. Mercury is cheap, and if you have some left over, it costs much more to
dispose of it than to obtain it in the first place!

While researching the above, I found this lovely page that discusses gas discharges, and touches
on mercury and its effects on ionization and resonance energies. It's a good read, and includes amusing
phrases like "collision of the second kind".

http://mysite.du.edu/~jcalvert/phys/dischg.htm

- John

[Dekatron42]

If I remember correctly there is at least one patent on Nixies that mentions 2.5mg and/or 3.5mg of mercury, and it also discusses several methods of releasing the mercury from the small glass capsules - I can't find the patent right now but I think it was a patent by Burroughs as I remember that one picture showed exactly how they have done it in their B5092 Nixie.

 

/Martin

[Terry Kennedy]

On Wednesday, August 28, 2013 1:28:00 PM UTC-4, Dalibor wrote:

Why we (pinch seal makers) are not going anywhere? Look to Rodan CD47,
there is also pinch seal.. But it would be definitely better to have
disc shaped stems.. There are companies that produce them, but for
high prices. I will definitely try to build a machine for making flat
stems, but that is far future..

 

Perhaps I can provide some info. I used to work in a glass factory, where I was one entire department (bead). I'll provide as much info as I can about the processes I performed, and what I know about the other processes.

 

Surplus pill presses (from pharma prototype labs, not the huge machines used for pill production) were fitted with custom dies which were used to form a glass + wax + dye mixture into a raw bead. There was an amazing amount of tolerance for most beads (after all, I was an 18-year-old kid at the time - the mid-1970's). The beads were collected in a hopper. I built the hopper and gizmo to move them into there (and blow off any loose glass) by using microswitches triggered at various points by the up-and-down movement of the press. They operated air valves which would then blow the finished bead off the press platen. This worked well for simple beads (1-hole round, 2- and 3-hole oval), but the more complex ones were made in very short runs (mainly for aerospace companies) and I often moved those by hand, as they would break or deform if just blasted into a hopper).

 

I'd then take the beads from the hoppers and pour them into Inconel mesh baskets and run them through the sintering furnace via conveyor belt. This would evaporate all of the wax and slightly melt the glass, fusing each bead into a solid unit. I don't remember the temperature the furnace, but it was dependent on the glass formulation used, anyway. I'd measure some random beads for QC and then bag them up for transport to the seal facility about 20 blocks away. With 3 presses running, I could produce several 1-lb bags per day, each countaining thousands of beads.

 

At the seal division, other workers would take the beads (from me and outside suppliers), metal leads, and (if needed) other metal parts and position them in carbon-block forms. These forms would have a grid of anywhere from a dozen to hundreds of complete seals. These were run through a furnace which was fueled by hydrogen gas. The beads would completely melt and flow around the wire leads and other metal parts. After cooling, they would then be removed from the forms, inspected and packaged up to send to customers. I'll see if I can find any of the stuff I took when I left that job - I have a box full of assorted completed seals, a clear plastic resin block with some of the company's most popular products, and one of the carbon forms.

[Tidak Ada]

Nothing known about an amalgam as mercury supplier ? Could be obtained from fluorescent tubes.

Afaik it is also used in 'modern' thyratrons.

 

eric

---

From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] On Behalf Of Dekatron42
Sent: woensdag 28 augustus 2013 23:29
To: neoni...@googlegroups.com
Subject: Re: [neonixie-l] Re: Something for the tube/nixie making people?

If I remember correctly there is at least one patent on Nixies that mentions 2.5mg and/or 3.5mg of mercury, and it also discusses several methods of releasing the mercury from the small glass capsules - I can't find the patent right now but I think it was a patent by Burroughs as I remember that one picture showed exactly how they have done it in their B5092 Nixie.

 

/Martin

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[Dalibor Farný]

Hi Terry,

this is great info, I am always surprised what kind of information folks here have ;-) really thanks for sharing it!

So, what kind of seals was produced this way? Were it seals for vacuum tubes with electrodes arranged in a circle? This process is completely different from what I have seen in documetary so far.. look here: http://youtu.be/GDvF89Bh27Y?t=20m55s

In the seal division, did the carbon forms consist of bottom and cover or did the glass just flow by its own weight into the carbon mould? Was there any inert atmosphere to prevent the metal oxidizing or the temp was so low that it was opened to air?

I would be really interested in photos of your stuff, that would certainly help! I hope You will find it!

There is a question what kind of glass and metal use for the seal.. I chose the tungsten wire and borosilicate glass. I dont have to anneal it during work (however I plan to anneal entire tube after tip-off), I dont have to be afraid of cracks.. The tungsten wire is also very resistent to fire, so I may expose it to flame repeatedly during making the seal. All other common metals would melt immediately (iron, copper, nickel..). But the disadvantage of that combination is that the quality of the seal depends on thickness of layer of the tungsten oxide on the wire as the glass makes bond with the oxide, not the tungsten.. It could be difficult to control it in a furnace.. And also the boro glass needs working temperature at least 1200C, quite a lot compared to 900-1000 for lead glass. 1200C is a limit temperature of common lab furnaces..

Dalibor 

2013/8/29 Terry Kennedy <terry+go...@tmk.com>

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[Terry Kennedy]

On Thursday, August 29, 2013 6:29:51 AM UTC-4, Dalibor wrote:

So, what kind of seals was produced this way? Were it seals for vacuum tubes with electrodes arranged in a circle? This process is completely different from what I have seen in documetary so far.. look here: http://youtu.be/GDvF89Bh27Y?t=20m55s

 

Most products used eiither single green round beads or oval brown 2- or 3-hole beads, and went to make bases for crystals. The company's most popular product was a metal base with 2 leads and green beads, which was sold to Motorola which made the finished crystals. These were apparently used in TV sets.

 

The other top sellers were also crystals. Most were the same metal-base-and-can variety (we didn't make the cans), but there was one which was a transluscent glass base which had a blown glass can, which another division across the production floor from me made.

 

But there were a good number of low-volume esoteric products. We made bases for Western Electric hybrids (round bases, lots of pins). We had one customer we made octal tube bases for, but out of metal, with green and gray beads as seals. There were some aerospace customers we made complex bases for - anywhere from 6 to over 20 pins in a translucent glass base. The "inside" part of these pins usually had a "shepherd's crook" bend, though some were straight. Many of these products had concentric rows of pins.

 

In the seal division, did the carbon forms consist of bottom and cover or did the glass just flow by its own weight into the carbon mould? Was there any inert atmosphere to prevent the metal oxidizing or the temp was so low that it was opened to air?

 

I believe all of the forms were just bottoms. I never saw a multi-piece form.

 

Most of the pieces I had were still bright 20 years after I collected them. I don't know how they would oxidize at higher temperatures. Some of the commodity pieces (mostly the brown-oval ones) had oxidized to a dull dark gray. Some rusted.

 

I don't know if they used any inert gas. If they did, they didn't go through a lot of it (compared to hydrogen).

 

I would be really interested in photos of your stuff, that would certainly help! I hope You will find it!

 

I will try to track them down this weekend. There's two places they could be, but both are many dozens of un-organized "banker's box" storage boxes.

[Nick]

From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] On Behalf Of Dekatron42

Sent: woensdag 28 augustus 2013 23:29
To: neoni...@googlegroups.com
Subject: Re: [neonixie-l] Re: Something for the tube/nixie making people?

If I remember correctly there is at least one patent on Nixies that mentions 2.5mg and/or 3.5mg of mercury, and it also discusses several methods of releasing the mercury from the small glass capsules - I can't find the patent right now but I think it was a patent by Burroughs as I remember that one picture showed exactly how they have done it in their B5092 Nixie.

ISTR that this was done by having the Hg in a small piece if glass capillary tube (a few mm long, maybe 4mm?) and released by induction heating. This is how the Hg was measured too - just dip the end of the small capillary tube in to a pool of Hg and a standard amount is drawn up. You can see these empty capillaries in the bases of some larger tubes...

Regarding the vapour pressure - remember the tubes run reasonably warm when run continuously - lets say the maintaining voltage is 110V @ 2mA (I know it varies a lot), that means you may be dropping 70V @ 2mA = 140mW, enough to warm the tube. Bigger tubes with more current produce correspondingly more heat - I find bigger nixes often run at about 30C. CD47 has a drop of 90V @ 25mA = 2.5W.

Nick

[Dalibor Farný]

2013/8/30 Nick <ni...@desmith.net>

From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] On Behalf Of Dekatron42

Sent: woensdag 28 augustus 2013 23:29

To: neoni...@googlegroups.com

Subject: Re: [neonixie-l] Re: Something for the tube/nixie making people?

If I remember correctly there is at least one patent on Nixies that mentions 2.5mg and/or 3.5mg of mercury, and it also discusses several methods of releasing the mercury from the small glass capsules - I can't find the patent right now but I think it was a patent by Burroughs as I remember that one picture showed exactly how they have done it in their B5092 Nixie.

ISTR that this was done by having the Hg in a small piece if glass capillary tube (a few mm long, maybe 4mm?) and released by induction heating. This is how the Hg was measured too - just dip the end of the small capillary tube in to a pool of Hg and a standard amount is drawn up. You can see these empty capillaries in the bases of some larger tubes...

There should not be any air in the capillary, You have to prepare a procedure on its end will be a small sealed capilalry tube with tiny drop of mercury but *without* air, just a vapours of mercury. Once cubic millimeter of air will have a volume of 40 cubic millimeters in a tube with pressure around 20torr and that would certainly lead to shorter lifetime.. The getter could take care about it, but it is quite clumsy solution. 

[JohnK]

Am I missing something here ? - the capillary is open both ends and gets pumped down with the tube doesn't it, so air doesn't matter.

 

Or, are sealed ampules always made?

 I follow that a capillary can be used to gather up a known amount 'automatically'. Is that then emptied [blown?] into something else or used open or used sealed etc.

 

Some more detail please....

John K.

----- Original Message -----

From: Dalibor Farný

To: neoni...@googlegroups.com

Sent: Friday, August 30, 2013 6:35 PM

Subject: Re: [neonixie-l] Re: Something for the tube/nixie making people?

2013/8/30 Nick <ni...@desmith.net>

From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] On Behalf Of Dekatron42

Sent: woensdag 28 augustus 2013 23:29

To: neoni...@googlegroups.com

Subject: Re: [neonixie-l] Re: Something for the tube/nixie making people?

If I remember correctly there is at least one patent on Nixies that mentions 2.5mg and/or 3.5mg of mercury, and it also discusses several methods of releasing the mercury from the small glass capsules - I can't find the patent right now but I think it was a patent by Burroughs as I remember that one picture showed exactly how they have done it in their B5092 Nixie.

ISTR that this was done by having the Hg in a small piece if glass capillary tube (a few mm long, maybe 4mm?) and released by induction heating. This is how the Hg was measured too - just dip the end of the small capillary tube in to a pool of Hg and a standard amount is drawn up. You can see these empty capillaries in the bases of some larger tubes...

There should not be any air in the capillary, You have to prepare a procedure on its end will be a small sealed capilalry tube with tiny drop of mercury but *without* air, just a vapours of mercury. Once cubic millimeter of air will have a volume of 40 cubic millimeters in a tube with pressure around 20torr and that would certainly lead to shorter lifetime.. The getter could take care about it, but it is quite clumsy solution. 

--
Dalibor Farny
http://dalibor.farny.cz

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[Dalibor Farný]

I see.. That taking a known volume could really work. But it is difficult to use it directly in the tube (capillary with both ends open and a drop of mercury), the mercury would evaporate during pumping messing the vacuum system with vapours of mercury.. not good.

Dalibor

2013/8/30 JohnK <yen...@internode.on.net>

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[John Rehwinkel]

> I see.. That taking a known volume could really work. But it is difficult to use it directly in the tube (capillary with both ends open and a drop of mercury), the mercury would evaporate during pumping messing the vacuum system with vapours of mercury.. not good.

What you do is make a mercury trap. Heat a spot of your narrow tubulation tubing and blow a bubble in it. Tip the drop of mercury into the bubble and seal that tube to your vacuum system and the tube you're evacuating. Now arrange to have the bubble sitting in a little cup of acetone cooled by dry ice. The mercury will freeze, greatly lowering its vapor pressure. After pumping, let the mercury re-melt, seal off the tube from your vacuum system, tip the droplet from the bubble into your tube, and then do the final seal-off of your tube. Voilà!

- John