Homebrewing vacuum tubes

[Bacon, WA3WDR]

Here's one for the audiophools.  This tube is made out of a fishbowl and an ashtray.
http://www.sas.org/tcs/weeklyIssues/2004-05-28/review/art/triode2b.jpg

PS - it actually works!

[VE1IDX]

Fishbowl hey? I have an unused 40 gallon aquarium.Wonder how much power it would be good for.

[w1guh]

Reminds me of something...

Back in the early 60's it was customary to address QSL cards to the station call sign, followed by "Chief Op.  ----"  (Maybe it's still done today.)  Well, some lengthened that to "Chief Op. and bottle washer", etc.

I got one addressed to "Chief tube sucker."  How'd he know I was running home-brewed PA tubes?

 

Anyone else?

[k4kyv]

Hey...didn't Lee DeForest do that some 90 years ago?

Aren't the Chinese doing it now?  If they could get their quality control up to the old U.S. standards so that their tubes had as good or better lifespans than the original RCA's, G-E's and EIMAC's, there would be no reason not to buy them.  Just about everything else is made in China these days.

The main reason most people, maybe excepting the audiophools, seek NOS tubes is that the reliability of the Chinese variety is still questionable.

[KA1ZGC]

I got one addressed to "Chief tube sucker."

That's quite a message! 

--Thom
Killer Agony One Zipper Got Caught

[wa2zdy]

I got one addressed to "Chief tube sucker."  How'd he know I was running home-brewed PA tubes?

 

Thank you for the reminder never to read things on the internet while consuming soda pop.  By the way, I'm not interested in a replacement can of Diet Coke, but you might be hearing from my wife about her computer monitor being soaked with Diet Coke . . .

[w1guh]

 

[John Holotko]

Barium and strontium oxides are available commercially, as are metallic barium, sodium, and lithium. But they are considered as hazardous materials, so it would be difficult for a layman to obtain them. Those oxides are very caustic and soluble barium compounds are highly toxic. The metals decompose water (sodium can do so explosively), they oxidize readily in air, and they must be stored under kerosene, argon, or in a vacuum. The kerosene would have to be completely removed before a piece of this metal could be used as a getter. Some specialty firms carry tungsten wire, which could be used for the filament. Nichrome could be used if the filament is coated with BaO or SrO and the filament could then be operated at a lower temperature. A plain tungsten filament could be used, but it would not work as well as a coated or a thoriated filament.

Back when I was in high school I became fascinated with chenistry so I built myself a home lab. I remember ordering labware (cheap in those days) chemicals, etc. One day I decided to order some sodium metal. I'll never forget the day it arrived at the door. It was packed in a nailed shut wooden crate plackarded with hazmat labels. Inside the crate the sodium was sealed in a can (just like a soup can) and the can was embedded in sand of which the crate was filled. I remember my father cursing me ans yelling, "WHAT THE HELL DID YOU ORDER NOW ??!!!". It cost more for the crating and shipping than for the sodium istelf. Once the can was opened the sodium had to be stored under dry kerosene or oil. Sodium is soft enough to cut with a butter knife and the cut surface tarnishes instantly in air. And if you accidentally drop it in water... stand back !!

Upon graduating high school I studied chemistry in college. Then my interest in chemistry dwindled and I changed my major to mathematics/computer science.

[KL7OF]

Thoriated tungstun is available at your local welding supply store as electrodes for TIG welding.  Comes in 6 inch long pcs and a variety of diameters from 1/16 to 1/4 inch..It is marked as radioactive however the level is so low that it will hardly make my geiger click....No special handling is necessary, however I wouldn't carry it around in my pocket......

[k4kyv]

Once the can was opened the sodium had to be stored under dry kerosene or oil. Sodium is soft enough to cut with a butter knife and the cut surface tarnishes instantly in air. And if you accidentally drop it in water... stand back !!

What is "dry" kerosene?  All that I have ever seen was a clear liquid.  If mixed with water, the water settles to the bottom of the container.

I believe if you cool it to low enough temperature it turns into a solid waxy substance.  Sometimes diesel trucks have trouble in extreme cold because the fuel solidifies.  Maybe that's why an alternative name for kerosene is paraffin.

[John Holotko]

Once the can was opened the sodium had to be stored under dry kerosene or oil. Sodium is soft enough to cut with a butter knife and the cut surface tarnishes instantly in air. And if you accidentally drop it in water... stand back !!

What is "dry" kerosene?  All that I have ever seen was a clear liquid.  If mixed with water, the water settles to the bottom of the container.

Kerosene that is relativel;y "pure" and containing no visible water and as little moisture as possible.

[David, K3TUE]

So the term "dry" is referring to it's hydrophobic properties and emphasizing the fact that it does not contain water mixed in it?  Or is it referring to an especialy pure form of kerosene which has the mixxed in water removed?

[W3SLK]

David said:

So the term "dry" is referring to it's hydrophobic properties and emphasizing the fact that it does not contain water mixed in it?

That is correct. We have toluene dryers at work. The toluene is run through a molecular sieve at about 220°F. This is all done under a blanket of nitrogen. Any moisture in the toluene reduces the yield of the batch to which it is applied.