DIY Vacuum Tube Maker

Great video presentation, much better than any episode of the How It's Made TV show that I've seen. Fire, and lots of shop-made metal parts to be observed. Resistance spot welding and induction heating, too.

It looked as though the equipment he was using was all shop-made, and at the end of the video, it shows the guy making parts in a well equipped machine shop.

FWIW, and contrary to popular belief, contained vacuum doesn't have to be performed by using a vacuum pump. When a vessel is heated to a high temperature, it's fairly well evacuated of air. Sealing the vessel/envelope while it's hot can be performed fairly easily when the envelope is glass, whether it's a small vacuum tube or a CRT.

A simple grade-school demonstration in the early 1960s involved dropping a small burning piece of paper into a milk bottle, and placing a hardboiled egg on top of the opening, as the flame went out. That was a time when milk came in a heavy reuseable bottle with a large neck. Of course, this didn't demonstrate the evacuation process by external heat, it was just fun to see.

WB ......... metalworking projects

I liked how he imitated a doctor delivering a baby when he held up the "newborn" upside down by one of the leads. -- Funny!

I'll second that opinion...

The egg was sans shell as I recall. :)

I also remember the teacher collapsing (imploding?) a gallon tin can with condensing steam by screwing the cap on the can after boiling a little water in it.

Jeff

The person in the video is Claude Paillard, F2FO:

This post brings me back a bit. One of my friends fathers worked for a vacuum tube manufacturer (Eimac) and would patently explain any question presented by one of the boys hanging out in his garage.

I remember him explaining that the silver you saw on the inside of a tube was the last step in removing all of the oxygen from the tube. When the tube had been pumped down and sealed off, there was a heating element that would vaporize a but of silver and the vapor would bond with the remaining oxygen and condense on the inside of the tube. The term for this was a getter as it would "get" the last bits of stray oxygen.

This was the same guy that thought us how to drill a hole in glass using a copper tube and a slurry of abrasive restrained by a clay dam. He also explained why it was a real pain to drill stainless steel and showed us how it could be done by holding pressure on the quill of the drill press with one hand and using the other hand to turn the pulley. No destroyed bit and no work hardening of the stainless.

I don't know whether silver is ever used as a getter; the usual getter is barium.

zirconium is used in large tubes, and phosphorus was used in some early tubes.

The silver looking stuff in Tubes is mercury. The getter was a pan of mercury and it was excited by an RF probe after the tube was sealed on the line to oxidize itself so when the filament is heated to red to red-white in color it would last many hours.

I've made tubes that you could pass a lunch box through without touching sides. The filament was as large as a pencil. It was a research tube. The largest I have put my hand on was 15 feet tall. The smallest was just larger than a pencil eraser.

I taught Tube design (circuit) and later, taught EE's who knew tubes solid state. So I had to know both designs and show relationships.

Eimac was the maker of Power transmitting tubes. I think of pyramid tubes and potato sized kilowatt transmitting rubes. TV and Radio as well as military used them. I think I have one or two in the shop. They used to advertise in ELECTRONICS magazine in the 50's. Those were the years.

Martin

Mart> >> This post brings me back a bit. One of my friends fathers worked for a

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The years of the 807 and 6146, 12A7, etc. etc?

Phosphorus is still used in incandescent lamps. I was involved in an R&D project recently that involved hand building a number of lamps. We had a heck of a time getting our hands on a small quantity of getter. Not only did the phosphorus make shipping difficult due to flammability, but it turns out red phosphorus is used in cooking meth and has become a controlled substance. Adding to difficulty was the fact that most of the lamp assembly operations have moved overseas and we were trying to beg the stuff from one of my customer's contacts at a plant in Mexico.

More like the 4CX250 family. I ran over 800 watts out of a pair in a TV Transmitter on Ch. 8.

Mercury? I would think that any residual Hg in the tube would vaporize with the heat of operation, presenting a real problem for the electron emission getting to the plate. Any "gas" in a vacuum tube is usually considered a bad thing.

I think that I had heard years ago that barium was most commonly used.You did mention that it was oxidized, but I thought the oxide was red in color. Most of my work with tubes was in lower power stuff, up to, say, 6GL6, etc.

I remember there were some diodes (high current ?) that used mercury in their operation, though.

The big ones are cool; I keep trying to get the engineer at our local University station to save a defunct transmitter tube for me (I do a weekly volunteer stint there as a DJ).

Joe

As I recall there were various elements (or compounds) used as getters . . .

Some of the old broadcast tubes were quite large. I went into one of the border Mexican stations, you know the type that was directional into N. America. One the roof was a large wooden-slatted cooling tower. Inquiring as if I had stumbled into an old-fashioned ice plant by mistake, I was informed that the tower was cooling water used in the plate circuit of the final amplifiers.

Mercury? I would think that any residual Hg in the tube would vaporize with the heat of operation, presenting a real problem for the electron emission getting to the plate. Any "gas" in a vacuum tube is usually considered a bad thing.

I think that I had heard years ago that barium was most commonly used.You did mention that it was oxidized, but I thought the oxide was red in color. Most of my work with tubes was in lower power stuff, up to, say, 6GL6, etc.

I remember there were some diodes (high current ?) that used mercury in their operation, though.

The big ones are cool; I keep trying to get the engineer at our local University station to save a defunct transmitter tube for me (I do a weekly volunteer stint there as a DJ).

Joe

-- snip --

-- snip --

Was??

The really big ones - Ignatrons (sp) used arc points and were the

10,000 amp class of SCR's. Still in use I suspect - plating plants....

Many power amp tubes of all sort used the stuff - I have some in the shop. The internal arcing - getting the getter to activate and vaporize onto the walls was done by an RF probe that injected through the glass (acting like a cap). Many power rectifiers and power triodes (like two fists on top of each other) had Hg in the current flow.

I might have one of those in the shop, but seems to me it was replaced with solid state.

Heat in the normal tube wasn't enough to activate atom mobility.

It is a small point that is in a cup and then coats a small area of the glass.

Martin

Mart> >

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The largest ones I saw were those Klystrons that people climb into in order to change the filament. They had a swimming pool that had 'blue' water within as a cooling start - and used an isolation tank to transfer the heat to a pool attached to a large body of water.

Naturally the blue was nuclear in nature. Martin

Mart> As I recall there were various elements (or compounds) used as getters . . . >

border Mexican stations,

large wooden-slatted

by mistake, I was

final amplifiers.

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I don't know if they are THE maker they were at one time. So many companies are into the game now.

Martin

Mart> >

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