Unknown X-Ray tube - Page 1
Forum section: electronics / general

author: Dajgoro
author_rank: Frequent Contributor
timestamp: April 08, 2014, 11:09:28 pm
content: Hi.Today I got a x-ray tube as a present from a friend.It is a old x-ray tube that is not used anymore, but the problem is that I know nothing about it.Since I got it, it would be nice to know how to use it.As for using it, I think I won't keep it, I have somebody in mind which has a good propose for it(research stuff).The only thing I know is that the manufacturer is Eureka, or something like that...Btw. The schematic in the background has nothing to do with the tube.

author: denelec
author_rank: Regular Contributor
timestamp: April 09, 2014, 09:59:37 pm
content: X-rays can beverydangerous!Be careful.High voltage + dangerous radiation = Lot of possibilities for disaster.

author: N2IXK
author_rank: Frequent Contributor
timestamp: April 09, 2014, 11:01:14 pm
content: Yes, the danger of playing around with these can't be overstressed. In addition to the radiation hazard and need for proper shielding/dosimetry, they need a high voltage power supply generally >50 kV, capable of delivering far more current than is needed to kill you.The actual operation is simple, high voltage from anode to filament, low voltage at a few amps needed to heat filament. Connect as forward biased vacuum diode across HV supply. Adjust current (and X-ray output) by varying filament voltage. Some tubes have dual filaments, to select beam size/shape. Yours appears to be of this type. Tube may need to be operated in an oil bath for cooling and insulation.Eureka is a well-known manufacturer of these things.

author: Dajgoro
author_rank: Frequent Contributor
timestamp: April 09, 2014, 11:17:31 pm
content: Quote from: denelec on April 09, 2014, 09:59:37 pmYup, that is why I don't want it in my house anyway, a friend already took it.Now I have watch out what he is doing with that...QuoteAny idea what that voltage might be? 6.3V?Also, can such a big tube be operated in a decent way to produce a low intensity x-rays?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: April 09, 2014, 11:27:07 pm
content: Quote from: Dajgoro on April 09, 2014, 11:17:31 pmNot really - low voltage x-rays won't make it through the glass - you need a beryllium windowed tube for that.Although you could generate low beam current, higher kVp outputs that would go through the glass, the high voltage means you'd probably need to run it in oil.I'm not sure if the normal filament current would make a nice glow to use for mood lighting... that may be the only sensible re-use.

author: N2IXK
author_rank: Frequent Contributor
timestamp: April 10, 2014, 12:04:24 am
content: Quote from: Dajgoro on April 09, 2014, 11:17:31 pm6.3 would be a good test, especially if all you want to do is light it up as a display or whatever. Should light it well.

author: jquinn11733
author_rank: Contributor
timestamp: April 10, 2014, 12:40:17 am
content: Pardon my lurking, but X-ray tubes typically have beryllium windows. Beryllium metal and compounds have high toxicity. Check berylliosis online. Tossing an X-ray tube in the garbage is not a wise move.The HV dangers are real, when powered. The radiation dangers are real, when powered. Both are severe. The beryllium dangers are ever present, when a X-ray tube is not powered. Never disassemble X-ray tubes, unless you have the proper ventilation, PPE, etc...regards,-Jim

author: N2IXK
author_rank: Frequent Contributor
timestamp: April 10, 2014, 12:55:55 am
content: This is an all-glass tube. No Beryllium window to worry about.Most significant metallic content would be a few bucks worth of copper and tungsten.

author: colinbeeforth
author_rank: Contributor
timestamp: April 25, 2014, 03:37:34 pm
content: This is a small xray tube and it has no window. It will probably only tolerate 10 seconds of operation before the anode starts melting and that will short the power supply. The actually efficiency of conversion of electrons to xrays is terribly low, because it depends on an electron striking the atom at a precise angle. Since matter is largely open space, the number of electrons in the beam from the cathode that are converted to xrays is tiny. Since the operating current of this tube is probably only a few tens of milliamps, the whole thing is perfectly safe. The tube can't generate enough xrays to be harmful before it melts. It's self limiting and can't hurt anyone even if they tried. I know we all love scary stories, but most real risks can be managed with a little care. For example, motor fuel, it's explosive potential is truly quite amazing. Yet we put our children into a mobile explosive carrier, drive to an airport and fling them high into the sky at over 500km per hour to go on annual holidays. Basically, we are terrible at risk perception. If we perceive a benefit (holiday) we'll put ourselves and our children in real danger. Frankly, the hammer in your garage is a far more dangerous artefact than that xray tube. Read crime statistics, more people die of hammer attacks each year than from xray exposure. Should we force everyone to store hammers in locked safes and demand every hammer in our society is registered? Will hammer users require safety training and licensing? Some risks can be managed, some not so easily, life has no guarantees, but knowledge can free us from baseless fears.

author: Teledog
author_rank: Regular Contributor
timestamp: April 26, 2014, 03:19:49 am
content: The beam from a tube like that typically exits at 90 degrees, hence the "no window"..it's coming out the side (round exit window on the side)And yes, minimum 50kV..typically 60-80kV (perhaps more)Yes, they only run for milliseconds (or the tube will smoke.. or the xformer will)The xformer is typically bathed in oil to prevent overheating/arcing, hence the heavy head on dental units.If you can get some old "intensification screens" from dentists/labs ...the x-rays show up quite well (scatter & all)G'luck & wear your lead panties!

author: TerraHertz
author_rank: Super Contributor
timestamp: April 27, 2014, 01:24:05 pm
content: Wow, it's very beautiful. As a sometimes collector of old vacuum tube weirdness, it makes me jealous.I notice that inside the glass, it appears that there is still a domed metallic 'window'. The topology suggests that the X-ray producing electron beam target is behind that window, inside the copper block. Not sure _why_ there's be a metal dome-window like that, inside the glass vacuum shell. But it seems quite possible that the metal dome may be made of beryllium.So if that glass envelope ever breaks, the tube is severely dangerous - risk of beryllium poisoning. You might mention that to your friend.

author: XynxNet
author_rank: Regular Contributor
timestamp: April 27, 2014, 04:28:48 pm
content: Minimum HV can be anywhere from 5kV+. Higher/other voltages are used to optimize contrast between different materials.

author: calexanian
author_rank: Super Contributor
timestamp: April 27, 2014, 04:51:05 pm
content: The tube just sitting there is not harmful. Make some kind of desk display out of it or something. Better than tossing it out. X-rays are only generated with it is powered. they dont hang around. They are like light. You can't bottle or save light for later, etc.. Same applies here. Also about the beryllium. Don't worry. Its always alloyed with copper in tubes and unless you are physically handling it particluate form you have no real concerns. After all, its sealed in the glass envelope.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: April 27, 2014, 10:11:10 pm
content: Quote from: calexanian on April 27, 2014, 04:51:05 pmA beryllium windowed tube does have exposed metal on the outside "Window" is the clue....All-glass tubes don't have beryllium AFAIK

author: calexanian
author_rank: Super Contributor
timestamp: April 28, 2014, 05:29:18 am
content: Quote from: mikeselectricstuff on April 27, 2014, 10:11:10 pmBeryllium copper side rods are very common in receiving tubes. I don't want to sound like i am going off on you or anything, but I am really getting tired on this forum of being so literal and specific about everything. Just because we are looking at one specific tube type does not limit the scope of the conversation to that one type. I have a little knowledge about the manufacturing of tubes and like being helpful. When people try to nit pick I feel bad. Its why we don't do audio..http://www.mu-inc.com/This is M.U. incorporated. My friends company in Oceanside CA. She still manufacturers a few types. In the middle of the table in the picture is her X ray tube offerings. I help her by repairing production equipment and engineering problems that come up. Literally she is a one woman show.

author: TerraHertz
author_rank: Super Contributor
timestamp: April 29, 2014, 02:50:44 am
content: Quote from: calexanian on April 28, 2014, 05:29:18 amThat's awesome! Much respect to her.Heh, and I have the exact same old bedcover that she's used as a backdrop in this picture of a beautiful HV rectifier valve:

author: calexanian
author_rank: Super Contributor
timestamp: April 29, 2014, 05:24:00 am
content: Her son put the site together one day. Just for the heck of it. That's the 6303 rectifier. It is still used as a damper tube and rectifier in Hawk Missile system radar trailers and a few other guided missile systems that basic trailer has been adapted to. The peak reverse voltage tests in that tube go well over 50KV in the test set. Talk about x rays! we use a lead shield for that one! Somebody came in and tested for the exposure level and it really was not bad. The shield is not really required, but it makes you feel better. The pulse modulator clipping service test is a hair raiser cause you are intentionally testing a sample to arc point! Everything is huge at those power levels and a noisy. Not only the 60HZ buzz, but the actual pulses are a unique sound. I forget the exact frequency but its under 100hz. that beating against the 60hz noise is unique. Lots of Perspex shielding going on in that test set!6303 X-80 rectifier data sheethttp://frank.pocnet.net/sheets/167/6/6303.pdfThe modulator test set has two hydrogen thyratrons basically in a totem pole configuration forming a big pulse into a coil and the damper diode under test has to basically endure the shunt current of the flyback pulse, and withstand the peak voltage of the input pulse spike. Hair raising!! tens of thousands of volts at peak pulses of hundreds of amps when it all goes wrong!

author: TerraHertz
author_rank: Super Contributor
timestamp: April 30, 2014, 06:51:47 am
content: I was still wondering why that X-ray tube seems to have a metal dome inside the glass envelope, so the X-rays obviously have to pass through both the metal dome and the glass.It just occurred to me - it's an X-ray lens!The X-ray origin will be a metal anode target inside the hollow cup of the copper block. Electrons from the cathode filament (why are there two different filaments?) hit the target, and X-rays are emitted in all directions from the impact area.So, if they can be focused somewhat, it's advantageous. But... the gain from focusing has to be more than the loss from passing through the metal dome/lens or it's pointless.So... what is that 'lens' likely to be made of? An actual big lump of beryllium?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: April 30, 2014, 07:47:22 am
content: Quote from: TerraHertz on April 30, 2014, 06:51:47 amMore likely a filter than a lens, maybe to stop soft x-rays affecting the glass?

author: calexanian
author_rank: Super Contributor
timestamp: April 30, 2014, 09:15:35 pm
content: The actual X ray "Target" Inside the copper structure is most likely a very clean tungsten disk what if we were looking down on it we would see inside. The glasses used in those tubes are relatively transparent to X rays.