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Want to trade for EHT electron tube rectifiers.

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Arcstarter

Sat Oct 16 2010, 12:18AM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

For some X-ray experimentation, i need some HV rectifiers as a very cheap X-ray source. The type i am thinking about is the 30kv ones with the top cap, from old TVs and such. EHT shunt stabilizer tubes, such as those that Plasmatron has used for Xrays work too, as do many other tubes that have a max operating voltage of around 30kv or more.

3A3, 6EN4, A267, and PD500 are good part numbers. If you have something like it, and you at least know it has a strong vacuum, i am interested. Even if the filament is dead i can at least run some tests.

I have some slow halfbridge IGBT bricks, and one fullbridge worth, and a 9 inch solder on ceramic standoff, 1.6Kw E ferrite cores, ignition coils (HEI and standard can), muffin fans and other odd bits and ends i am more than happy to trade. Just let me know what you are looking for, i may have what you need.

Proud Mary

Sat Oct 16 2010, 08:07AM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Don't bother with the 6EN4, Arcs, as it was designed as a safer replacement for the X-ray fun loving 6BK4B.

"Features of the 6EN4 include built-in X-radiation shielding and additional design and specification controls for the reduction of X-radiation output."

This modification resulted in a maximum X-ray output of 0.5mR/hr in normal use.

The 6BK4C was also designed to have a significantly lower X-ray output than its predecessors 6BK4A, and 6BK4B, though here the radiation reduction was only to 1.5mR/hr.

pauleddy

Sat Oct 16 2010, 04:07PM

Registered Member #2909 Joined: Wed Jun 09 2010, 12:31AM
Location: fort belvoir, Va USA ( south of DC)
Posts: 145

whould this one work?

its a 1BV2 from a Philco tv from the late 60's

Arcstarter

Sat Oct 16 2010, 11:37PM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

Proud Mary wrote ...

Don't bother with the 6EN4, Arcs, as it was designed as a safer replacement for the X-ray fun loving 6BK4B.

"Features of the 6EN4 include built-in X-radiation shielding and additional design and specification controls for the reduction of X-radiation output."

This modification resulted in a maximum X-ray output of 0.5mR/hr in normal use.

The 6BK4C was also designed to have a significantly lower X-ray output than its predecessors 6BK4A, and 6BK4B, though here the radiation reduction was only to 1.5mR/hr.

"In a Marx driven regime such as this, however, there is almost no difference in output, between the leaded and unleaded versions of the tube, since the energy of the beam is greater than 100keV!"

Quote taken directly from Plazmatron's site:

It was a Flash X-ray setup with the 6EN4.

I will be using a setup much like his, and it worked for him. But, since you say that, maybe it wouldn't be the best thing to start with.

I would love to have an 6VS-1 and run it CW, like Plazmatron's work (hey, he explains things in a way i understand :O).

@pauleddy: Yes it would surely work. Have any more?

Also, do you have a datasheet? I cannot seem to find one

pauleddy

Sun Oct 17 2010, 03:23AM

Registered Member #2909 Joined: Wed Jun 09 2010, 12:31AM
Location: fort belvoir, Va USA ( south of DC)
Posts: 145

this is my only one, but i can try to find the data sheet, i whould have to ask my gramps for he used to repair tv in the 50's-70's mabe he has some

plazmatron

Sun Oct 17 2010, 03:50AM

Registered Member #1134 Joined: Tue Nov 20 2007, 04:39PM
Location: Bonnie Scotland
Posts: 351

Arcstarter wrote ...

.....6EN4....

I will be using a setup much like his, and it worked for him. But, since you say that, maybe it wouldn't be the best thing to start with.

Probably not the best thing

PD500`s are a good one to start on. They are relatively inexpensive too.

The main point of driving the leaded version 6EN4, was to illustrate the point, that pretty much any tube could be tortured into producing a useful quantity of x-rays, so long as enough power was dumped into it in a short enough space of time

There is also no need to build an insanely huge Marx generator either. 100kV should be more than enough, in fact, I have just put together a 100kV bank, as the 300kV one is just too powerful to use around measuring equipment.

Don't forget to keep an eye out for EHT rectifiers too, they often show up at giveaway prices.

Weston

Sun Oct 17 2010, 06:43AM

Registered Member #1316 Joined: Thu Feb 14 2008, 03:35AM
Location: Cambridge, MA
Posts: 365

I have (right to left): 6LJ6a/6LH6a, 3a3c and 6bk4c/6el4a. Willing to trade something for all three of them. They are doing me no good sitting in my cool tube box (I have a slight tendency to collect tubes

). Is the 3a3c any good for X-rays Proud Mary? The C suffix on the 6BK4c makes me think the C suffix means a shielded glass version...

Proud Mary

Sun Oct 17 2010, 09:23AM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Weston wrote ...

Is the 3a3c any good for X-rays Proud Mary? The C suffix on the 6BK4c makes me think the C suffix means a shielded glass version...

In the US RETMA electron tube numbering system, the A, B and C suffixes mean backward compatible modifications/upgrades/design revisions of the original version, so "C" means that the design has been modified three times.

Now as to your 3A3C, I've never seen a TV valve that had so much detail of its x-ray properties in its data sheet.

In its first iteration, the 3A3 datasheet makes no mention of X-rays at all:

The 3A3A data sheet says that X-rays are produced at more than 18kV, which can harm the human body if short range expsoure is prolonged. In this case, the data sheet writer goes on it French, appropriate sheilding should be used, either iron plate, or lead glass.

By the time we get to 3A3C, the datasheet gives us - most unusually - X-ray exposure levels for different anode voltages:

The 3A3C datasheet doesn't mention that X-ray shielding has been added to the design, but I would expect it had, as with 6BK4C.

Weston

Sun Oct 17 2010, 04:44PM

Registered Member #1316 Joined: Thu Feb 14 2008, 03:35AM
Location: Cambridge, MA
Posts: 365

Third line of the first paragraph from the datasheet: "the 3A3-C features built-in X-radiation shielding ". looks like the 6LJ6 has x-ray shielding too :( . If you can wait a bit I can pick up some more HV rectifier/shunt regulator tubes when I visit the surplus store (hopefully this upcoming weekend or the one after). They have a bunch of them, it just seems that I randomly picked 3 that have built in shielding....

Arcstarter

Sun Oct 17 2010, 08:02PM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

Weston wrote ...

Third line of the first paragraph from the datasheet: "the 3A3-C features built-in X-radiation shielding ". looks like the 6LJ6 has x-ray shielding too :( . If you can wait a bit I can pick up some more HV rectifier/shunt regulator tubes when I visit the surplus store (hopefully this upcoming weekend or the one after). They have a bunch of them, it just seems that I randomly picked 3 that have built in shielding....

Please Weston, you have talked to me on IRC. You know i have nothing but time

. But, i am still interested in your tubes.

I know that my 3A3 made Xrays. It was about 60kv from a couple ignition coils. I covered my camera with 8 layers of alu foil for RF protection and to block out light (i used 8 layers because i wanted to see if there was a difference in the amount of X-rays that hit the CCD on the camera). Next time i will actually use shielding, though my camcorder was on its tripod and i held the end of the tripod.

At Plazmotron (FINALLY i will stop misspelling your name!), yes my Marx is theoretically 80kv :). But, im not so sure that the erected capacitance is high enough. It is about 150pf. But, i guess the current does not matter so much, as long as the voltage drop is high enough. I am going to try the ignition coils anyway. It is a short pulse, and as long as there is still the full voltage across the tube i expect X-rays.

Now, my sister-in-law needs to hurry up with those intensifying screens and film etc. She is a dental assistant, so she can give me their thrown out X-ray things. They have a panoramic X-ray machine, so she has some big ole films.

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