Homemade Vacuum Tube

[AlekZ]

I was here more than one year ago

Now I make better tubes. For example, it's power triode:



The parameters:

diameter 90 mm
height 18 cm
tungsten cathode
filament voltage ca Vf=11V
filament supply If=1,85A
life time (to break cathode) ca 7200h
gain factor K=ca.5
transconductance S=0,8 mA/V
power dissipation P=12W

Characteristics during If=1,8A:

[v4lve lover]

NICE .

i found it through google while doing research .
that is a VERY nicely made tube .

a shame nobody had intrest in this at the time .
i would like to know how you made this one .

EDIT forgive my topkick i just was so excited not to find a threat about snake oil and WE300B's but some proper discussion .

[AlekZ]

Some time ago, I prepared film about it. And I prepared better tubes.

[quikie22]

WOW!!! Link for the film?

[M Gregg]

Originally Posted by quikie22

WOW!!! Link for the film?

2nd for film link!

If I made one of these the vacuum would leak like bucket full of holes..LOL

One of the 7 wonders of the world how to get wire through glass with a perfect seal.

Regards
M. Gregg

[TheGimp]

Dumet wire.

It's a special alloy designed for feeding through glass.

Thermal coefficeint closley matches that of the glass used for the tube/lamp, whatever.

copper adhers to glass well so the outer layer is copper.

I too would like to see the film.

What level of vacuum do you pull in the tube?

Is that a getter in the top?

[v4lve lover]

the wire your talking about is dumet wire .
for the construction of vacuum tubes you need a lot of materials .
i'd love to go in dept about it .

and the seals aint so hard . you just need
* dumet wire for the seal itself
* NI48 FE52 wire for the support rods .

weld em to make a seal
glass . tungsten . nickel sheet/strip metal . a bounch of rare earth metals . forgot ofcourse mica ,

the machines are a completely differend story tho.
my guess is it would cost 50k+ to make the equiptment for 1 type of tube . and that also depends if you outsource or homebrew equiptment

most difficult part would be a decent grid winder / and or a stem maker .
semi automatic bulb maker would save you SO much production time

like i said .
id love to go in dept about it

[TheGimp]

Last time I played with vacuum was in college around 1978. In HS, I ran two Frigedare rotary vane compressors in series. (You could strip them out of the housing and set them in a pan full of compressor oil to run them, but had to feed them a little oil through the pickup tube occasionally.) A single frigedare compressor would go below 0.5Torr (confirmed in the physicas lab at USC (SC not CA)), and two in series were supposed to be good to .01 Torr. I was working with lasers at the time, building a HE-NE cold cathode laser. I got most of my supplies from a local Neon Sign company. Later I got a HiVAC two stage rotary vane pump and was working on building a mercury jet difusion pump but never finished it.

How difficult would it be to use a lathe for a grid winder? Totally impractical?

At the time I was using "Procedures in Experimental Physics" by Strong as a reference for making equipment.

[smoking-amp]

My father built some "tubes" long ago from just ordinary food canning bottles with rubber gasket seals. Wires thru the gasket or holes drilled/ground in the glass bottle with screws/washers/rubber gasket/glue seals. The standard bottle spring clamp held the glass cap and gasket under compression. (you would want to use Viton gaskets for high vacuum now I think.) He used some assorted real tube guts to conjure up new tube types. I don't know what he used to evacuate them, but probably was some fridge compressor or surplus pump.

Another neat book for building "projects" is "Building Scientific Apparatus" by Moore, Davis, Coplan

You would need an awfully fine thread attachment for a lathe, I think, to wind grids. Some of the coil winder machines have an infinitely variable cam arrangement for winding pitch, just the thing.
Maybe if the feed gears for the thread attachment on a lathe were changed, could get fine enough pitch. But the grid support rods normally have notches in them for the wire to drop in. Then they get roll crimped to hold the wires.

I have a Varian oil diffusion pump and a two stage roughing pump and a complete Balzers Turbomolecular pump in storage along with assorted gauges. Had it all working at one time. I used to live near a scrap metal yard that got a lot of Perkin Elmer and SVT semiconductor fab equipment. I found one vacuum setup once that had gold wire seals in all the flanges. Oil diffusion pumps are a dime a dozen at the right scrap yards. May never get back to using them unfortunately.

[AlekZ]

I told that I prepared better tubes. I found it in my webpage:

lampa T10 PWL

Unfortunatelly, there is not english version now.

About film: I'm looking for it in my computer. But remember that it's "big" file.
But now You can see some my aparature:

http://tubedevices.com/alek/pwl/aparatura/aparatura.htm

I have 5 vacuum units:
-with rotary pump and oil diffusion pump. The final vacuum is below 10E-6 Tr. It's for pumping my
vacuum tubes.
-with rotary pump and turbomolecular pump. The final vacuum is ca. 10E-6 Tr. In this unit is quadrupole mass spectrometer for testing residual gases in electron tubes etc. It's used rather for my experiments for new types of cathodes.
-with rotary pump and my own glass oil diffusion pump. I have it for fill neon or argon, hydrogen (etc.) tubes (nixies etc.). The ultimate pressure below 10E-4 Torr.
-with rotary pump for fill geiger counter tubes. The ultimate pressure ca. 10E-2 Torr.
-with rotary pump and oil diffusion pump. It's vacuum furnace for degassing details of tubes. The ultimate pressure below 2x10E-5 Torr.

About wires: for vacuum tight connectors metal-glass you need different wires. For example, for soda glass or lead glass you need wires FeNi or FeNiCo with copper shield. Im my country some people call it "FeNiKuMa", but I don't know why.
For molybdenum glass or kovar glass you need molybdenum wires.
For duran glass it should be tungsten wire.

Best regards
AlekZ