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Vacuum Tube Data -- Where?

Thread starter #1
I am currently doing some research on vacuum tubes. Part of this effort is to look at little-known ceramics and alloys used in their construction. The problem I've run into is I can't seem to find many well-maintained sources for vacuum tube data. I'm sure they're out there.

Another electro-tech topic: "Russian vacuum tube data -- where?" mentioned the website http://datasheets.electron-tube.net, but these days it appears to be offline. There's the Google option: but I have no idea which sites are safe to visit. Currently, Google patent search and wikipedia have gotten the best results, but I could use more data.

Any suggestions?
 
Thread starter #3
Looks like the system doesn't archive the pdf content. But it's a good way to help me match some part numbers to manufacturers.
 

unclejed613

Well-Known Member
#4
Thread starter #5
Yesssssss! This should keep me busy for a while.

On a related note, if anyone has tips on a good introductory tube project or part number; I could use some suggestions. Most of my work is with semiconductors, printed circuit boards, and vehicle instrumentation. But tubes are a new area I'm exploring.
 

unclejed613

Well-Known Member
#6
something like the 00A 01A, etc early triodes would be good for retro radio hobbyists. there were various types of triodes where the amount of vacuum would alter the characteristics. these were called "hard" and "soft" triodes

there also were devices known as Field Effect Triodes, that had the filament at one end, the plate at the other, and the grid was a metal sleeve on the outside of the glass. the tube was long and narrow, so the effect of the grid was electrostatic through the glass. the grid never went into conduction like it can with standard triodes.

if you want to get exotic you could make Crookes tubes where a beam of electrons are accelerated at a target, which casts a shadow on the far end of the tube, and the glass fluoresces from the electrons that miss the target. experimenting with a Crookes tube may require some shielding from X-rays produced when the electrons hit the target.

one interesting device that gets a lot of experimenters going is a Hirsch/Farnsworth Fusor which has a spherical "cage" electrode in the center, and a larger spherical screen or cylinder electrode around the outside. a small amount of gas, such as deuterium is left in the tube. when the center electrode has a high negative voltage applied, the positive gas (usually deuterium) ions accelerate into the inside of the center electrode and collide and the nuclei can fuse. because the center electrode occupies some space, the net energy released is less than unity, but the nuclei DO fuse. when deuterium is used, there should be some kind of shielding, as the reaction does produce neutrons and X-rays. a fusor can be used with just plain air molecules left inside without using deuterium for a lighting effect that is similar but relatively harmless.
 
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Thread starter #7
Okay. Actually, 01A was already on my watch list, so I guess that's good.

I didn't find the 00A or 01A today in-store unfortunately. I was definitely a good haul though...

12D4 - Diode (1 total: General Electric)
6AL5 - Dual diode (General Electric)
12CX6 - Pentode, Sharp-Cutoff (RCA)
5X8 - Triode-Pentode (3 total: General Electric, Sylvania, and Philco)
6X8 - Triode-Pentode (2 total: RCAs, different years?)
6BY6 - Heptode (RCA)

I'll probably start the diodes, since they seem the most straight-forward. I also found a bunch of data sheets at http://www.nj7p.info. It's pretty handy that the datasheet seems to be laid out just like any modern datasheet. I'll try to post up some related images and links soon.
 

unclejed613

Well-Known Member
#8
i would think the real hard parts of making tubes are 1) getting the right materials, such as the various oxides for cathode coatings, or thoriated tungsten wire for the filaments, and 2) stamping, wire forming, and spot welding equipment for making the plates and grid elements, and making those elements with very small tolerances. materials and tooling are probably your biggest hurdles. getter material is probably not easy to come by either. it was one thing to get the materials and tooling "back in the day" when everybody and their brother was making vacuum tubes, but very few companies are making tubes these days, so some of the equipment and materials might be hard to find.
 

atferrari

Well-Known Member
#9
This won't answer any of your questions but it is interesting anyway.
 
#10
These may be of interest as well, some less common styles for VHF - UHF - Microwave use:

http://www.r-type.org/exhib/aaa1242.htm
http://www.rfcafe.com/references/po...mily-tree-august-1963-popular-electronics.htm

I've got some 4CX250B valves (tubes) as those above, for ham radio gear I've built (& I still have one or two of the early 1900s four-pin triodes that have been mentioned, somewhere stored away).

Also an economy-size thyratron used to control a motor-generator set or amplidyne; there is a photo of that and some other vintage valve gear in one of my flickr albums, here:
https://www.flickr.com/photos/robertjenkins/albums/72157624433238366

The little wire recorder used three miniature wire-ended valves, the ones in the recordon are a bit more obvious.


If you are looking for other examples of practical valve equipment, have a look at 1960s / 1970s guitar amplifiers; the full schematics of most types are freely available online.

Edit - I decided to document the other vintage parts whilst I was thinking about them, the valve / tube photos are now in their own album here. It turns out most are five-pin rather than four-pin:
https://www.flickr.com/photos/robertjenkins/albums/72157690959508900
 
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Thread starter #11
12D4 Test Setup.JPG
Sorry about the lack of updates. I'm having some major home PC hardware problems that are still unresolved.

Anyway, I decided to start with the 12D4 Radio Corporation of America (RCA) diode, since it was the simplest on the list.

Filament Test:

Testing the filament was the first step. These tubes seemed to be fairly old, and I'm guessing printed date codes weren't common back then. I honestly didn't know what to expect if the filament had failed. To start, I checked the resistance across the two filament pins indicated by the datasheet (pins 7 and 8). The resistance matched what the datasheet implied. (The filament resistance isn't explicitly called out, but dividing the operating voltage of 12.6 V by the 0.6 A filament current yields the nominal value). The resistance was high enough to seem safe, so I connected the filament pins directly to the 12 V SLA battery...first for a split second, then for several seconds.

Luckily, there were no sparks, explosions, or wormholes created. The filament glows a nice orange, and you can see this along with the filament current in the attached image.

Diode Forward/Reverse Current Test:
I did a second resistance test to check for any conduction between the cathode and anode (plate). There was none, so it was looking safe to proceed testing the diode/rectifier function. I used a second SLA battery to supply the anode and cathode. I could have run the whole thing off one battery, but I wanted to see the filament run independently for now.

The datasheet indicated an anode voltage of +12 V should result in about 100 mA forward current. Sure enough, when I applied the 12 volts, the smaller current meter reported just over 100 mA. Reversing the voltage or applying voltage after cool-down resulted in no measurable current. So I think this one has PASSED.

Overall Impression:
So far it's going pretty well. I've read a little about tubes in the past, but they really only get a passing mention in most organized courses. I really wasn't sure of what to expect. It's also worth noting I did not restore the tube in any way prior to testing. That is: I didn't clean the pins or remove any dust or debris before-hand. I might clean them on a later date. The pins, batteries and meters were all connected through alligator clip wires.

I found the data for this tube on the site: http://www.nj7p.org/Tubes/PDFs/Frank/093-GE/6DA4.pdf

Unknown Data:
As far as rare/unusual materials go, I'm not sure if this tube contains any. The General Electric (GE) datasheet indicates the envelope is "T-9" glass. I'm sure of what that is (maybe borosilicate or phosphosilicate glass?). Also I've heard the color of the filament can provide clues about its composition (white for tungsten, bright yellow for tungsten-thorium alloy). This was clearly orange, so maybe this is a different material entirely.
 
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unclejed613

Well-Known Member
#12
Thread starter #13
Well, this is a pickle. On the glass, I can only see "12D4" inside an octagon, with "17M" printed below. I can't seem to fit the "17M" part into the above date coding schemes. Maybe there's something I missed. The attached plastic pin assembly has an Emerson code of 312839.

My much smaller 12CX6 pentode tube however has a date code of "NC" corresponding to March 1963. This is consistent with a U.S. patent code that is printed on the cardboard box: US 2714982 (granted in 1955). :cool:
 

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