Xray transformer high frequency or not?

[nielsquake]

I have someone willing to sell me the exact xray head shown in this video, I was wondering if any of you could tell me if you think this one is driven at mains frequency or if its an inverter type

/>The control board and capacitors on the outside give me an impression that its part of the driver circuit but its hard to tell. Maybe someone with more experience on these could tell me

On the outside is a 50hz sticker but I guess thats just so people know the input frequency for it.

[klugesmith]

Looks pretty clear that the HV transformer is high frequency (from size of core etc.)
And the non-oil-filled box includes high frequency inverter - what else would the power semiconductors be doing?
Are you getting a unit for the high voltage or for the x-rays?

[nielsquake]

Yea I figured with the ferrite, just wanted an expert opinion on it since the sticker on it said 50hz. Are you sure that board is an inverter btw? These things always have heaps of monitoring going on but that was my first thought as well. I want to use it for the transformer but who knows, I might try some fluoroscopy if I can get my hands on a nice radiation detector that works with xray and proper lead shielding so I don't blast my neighbors with high energy xrays lmao.

I plan to run it with a ZVS driver. How many watts do you think a transformer like that could handle for the input? would the core saturate or would the secondary burn if I used too much power. since I have a 2000w zvs driver so I thought I might be able to use it for it.

Thanks for checking btw! 

[klugesmith]

Whether you drive this with its own inverter or a DIY driver, remember the X-ray tube has a heat limit.   

Normal operation is less than 1 second of operation, at nominal current, separated by more than 1 minute of cooling time.  If the transformer is designed to handle much more than that, it's needlessly large and expensive.
You could get a clue by measuring primary and secondary wire resistance, and computing the copper loss in watts at nominal current.

For x-ray detection, pen-type fiber dosimeters are handy.  Here's one with 200 mR full scale range, being zapped by a dental x-ray generator. 

[nielsquake]

Thx for the info! would running at low filament current work if I want to run it for longer like 15 seconds? I heard the reason no to use it continuously is to prevent anode pitting/cracking due to the sudden heat difference. I do plan to implement convection cooling by running the tube under oil.
Since this tube actually has like 1mm of aluminium filtering I'm guessing removing those still allows for taking a nice xray even at low fillament current. IK it will produce dangerous soft xrays but I will be running the experiment remotely far away from me with dosimeter.
I have seen people run xray tubes significantly smaller then this one for up to 30s but they were using a voltage multiplier thing and not the actual xray transformer with high amp output. From the spec sheet I think I saw somewhere the original transformer takes a HF squarewave signal with peak of 25v so I guess if I get a small 25v battery it would be a good way to drive the HV site

[klugesmith]

Tube and transformer are oil-cooled in original application.   With 65 kV and 10 mA, anode would be heated with 650 watts; I bet if you ran for a whole minute the failure would be cracking of glass-to-metal seal at anode stem.

Of course you can dial down the HV current, and anode power, by reducing filament voltage.   If HV transformer secondary has a ground connection, that's a good place to insert a current sensing resistor.

[nielsquake]

okay, thanks a bunch for the info!

[nielsquake]

Tube and transformer are oil-cooled in original application.   With 65 kV and 10 mA, anode would be heated with 650 watts; I bet if you ran for a whole minute the failure would be cracking of glass-to-metal seal at anode stem.

Of course you can dial down the HV current, and anode power, by reducing filament voltage.   If HV transformer secondary has a ground connection, that's a good place to insert a current sensing resistor.

And how about if I run the tube under oil? also if I drive the transformer with 300w less, you think the secondary could handle that? with input voltage of 30v

[nielsquake]

I was also wondering what would be a good amount of turns to start my primary with. Usually I go 5+5 turns centertapped for all my flybacks but I want to be careful with this one and not fry it. It has been under oil since 1988 so I will not have to vacuum it and I will take it out without exposing it to air. I guess I could use the original primary but I don't know if I manage to figure out what wires are what lol. I also kinda like making my own and keeping the original intact since I don't want it to melt anything inside where the secondary is if it heats up too much..

[nielsquake]

thanks for the help on the transformer you all! managed to drive it inside the housing and got this cool xray pic.
Its my old broken samsung s8 plus

[klugesmith]

Nice work.  I've never made an x-ray image bigger than a postage stamp (dental film).

Just don't make a habit of energizing the x-ray generator when you are close.

Do you know anything about radioactive sources, like the sub-microcurie air ionizers in smoke detectors?
The dental x-ray generator, when ON at normal power,
is like kilocuries of gamma-ray decay activity.  At least dozens of TBq.

[nielsquake]

Thanks, also got some large intensifier screens comming in!
And yes I am well aware of the safety measure needed to take and don't run it anywhere near me. I was lucky enough there were no controllers inside the oil tank so I can run the tube inside its original housing (the one at the top of this thread) And that thing is shielded very well
I run it by plugging in the power in another room far away from it. my garage has very thick walls and the unit itself is pointed at the thickest ones. Don't plan to run it often but it's cool I managed to get a proper picture. The paper I used is one of those instant polaroid films I got for cheap.