Largest vacuum tube ever made
 

Largest tube in 1927 {edit} July 1927 popular science Tube Was a GE 100kw transmitter tube 7.5 ft tall
100 lbs copper jacket for water cooling was installed at Ge station WGY
for experimental use took 10kw to drive it! They did not list a tube number guesss they only made one.

http://books.google.com/books?id=Eys...TiAKDgI3mDg&sa

Interesting. I wonder if this tube went on to commercial use, and was eventually assigned a type number?

As far as early tubes in the 100 kW power class, there were at least 2 other types. The type 862 was a 5 foot long water-cooled beast, which saw service (20 of them- 12 as class C RF power amps, plate modulated by 8 more!) in the experimental transmitter built by RCA for WLW, when they were running under special authorization at 500kW output. A great page about the station with a lot of pictures:

http://hawkins.pair.com/wlw.shtml

A good picture of an 862 tube:

http://radioheaven.homestead.com/RCA862.html

The RCA datasheet for the 862:

http://tubedata.tubes.se/sheets/049/8/862A.pdf


The other early "superpower" tube was the Western Electric 320A, which was developed for Mexican "Border Blaster" station XERA. Only 9 were ever made, 8 for the XERA transmitter, and one spare. Some neat pictures and info:

http://www.oldradio.com/archives/hardware/WE320A.htm

http://hawkins.pair.com/mexblast.shtml


Of course, both of these "beastatrons" were soon eclipsed in terms of raw power. I believe the title of "most powerful tube" is still held by the Eimac 8974 tetrode, used in megawatt class shortwave transmitters and particle accelerators:

http://www.cpii.com/docs/datasheets/81/8974.pdf

That guy takes nearly 10 kW just to heat the filaments! 22.5kV on the plate at 125 *AMPERES* plate current for a shade over 2 MEGAwatts of RF output in class C.

That was great reading! thank you both for posting!

About 12 years ago, the Fry's Electronics in Silicon Valley CA had on display a radar tube. About 12 feet tall, and about 8 inches diameter, looked like a metal pipe painted red. Supposildy was used for military radar, that checked to see if any Russian nukes were on their way to us.

Yeah, I worked w/a fella who was an electronics tech in the Sub Service & he told me of HUGE tubes that they opened up & worked inside...I guess they evacuated 'em after servicing.

Price tag?
 

:scratch2:Just curious, what would one of those tubes cost?

that would cause a lot of work just decontaminating it before evacuating it!

The output tubes (Type 43 valve) used in the British "Chain Home" radar stations were designed to be opened up and repaired, rather than replaced. They were never actually sealed off, but continuously pumped down during operation to maintain a hard vacuum.

Some modern high power tubes (including the 8974 mentioned earlier) incorporate a built-in titanium ion sputter pump to maintain vacuum, even though they are sealed off. Conventional flash getters are inadequate for tubes with very large evacuated volumes.

Wonder if tubes used in spacecraft, like geostationary satellites, might be opened to the vacuum of space, to get rid of any gasses that were left when the tube was made on the ground. Probably not, as the mechanism needed to do that would be extra cost and weight. But imagine tubes not needing envelopes...

I have one of these tubes, a spare out of the Princeton Tokamak fusion project, and indeed the crate it comes in proclaims it as "the worlds most powerful electron tube".

--
Will

No, too much crap out in space, unless you go way out there.

--
Will

:worthless

VERY cool! I'm also a tube collector, but don't have anything nearly that big. Biggest one I have is a ~60kW water cooled tetrode.

Is your 8974 operational, or a dud? How did you end up with it? Tubes like that are usually rebuilt, and only get tossed if they fail catastrophically. Makes them quite unusual in tube collections.

I have a big 'un I found in an antique store that is about 10-12" tall. I put it in my display case w/my Danbury & Franklin Mint cars. It was a new in box Westinghouse WL 676. 4 prongs on the base, & a top cap.

A mercury vapor thyratron, used in various types of industrial equipment (welders, motor speed controls, etc.). If interested, the datasheet for RCA's version available here:

http://scottbecker.net/tube/sheets/049/6/676.pdf

Yeah...I got it for almost nuthin' 'cause it was just layin' out where any little kid could get it & bust it, & I told the woman running the store that it was extremely dangerous to do that, & she was opening herself up for a big lawsuit, potentially. OK, so maybe that was an exaggeration, but back when I was a Snarky Little Boy, I developed a "Radar" for finding stuff like this & foolin' w/it...Never broke anything, but I was just VERY dam luicky, too..And I'm sure there are OTHER Snarky Little Boys out there...