If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Registered Member #122
Joined: Fri Feb 10 2006, 12:55PM
Location: Milano Italy
Posts: 148
You don't need a special vacuum equipment, you only need a cheap double stage high vacuum pump PLUS SOME GETTERS
The pumps used by A/C installers, in combination of some kind of gettering can reach the requested pressure easily
i have this pump and i found many small nonevaporative anular getters (the type preferred for xray tubes!) plus these biggest nonevaporative getters (also used for xray tubes manufacturing):
remember, getters are shipped inside a sealed container in a protective enviroment, is advisable to never open the container except immediately before use, some radiograms become mandatory!
Registered Member #1134
Joined: Tue Nov 20 2007, 04:39PM
Location: Bonnie Scotland
Posts: 351
Yes, I have been watching some of those pumps on eBay, I must get around to getting one. Most of the air conditioning pumps pull a hard enough vacuum for soft x-rays, and with suitable getters, as you say, you`re home free!
Its one of those pieces of equipment I should have bought long ago!
What are you doing for glass to metal seals? Breaking the wires out of light bulbs?
Registered Member #122
Joined: Fri Feb 10 2006, 12:55PM
Location: Milano Italy
Posts: 148
What are you doing for glass to metal seals? Breaking the wires out of light bulbs?
no Some electronic components have a glass envelope, their pins are made with nickel-iron plated with copper and than covered with tin/lead; just pick a 1N4148 diode and a sandpaper, wipe off the tin/lead solder to expose copper plating and you have a perfect glass seal!
If you need bigger pins, use 1W zener diodes instead of 1N4148, they have bigger terminals.
Fabio, how do you flash your getters? Do you have an induction heater, or do you bombard them?
The getter in previous pictures have an internal heater and can be activated either by induction heating or by current.
This other getter should be activated by induction heating (i used a ROYER oscillator for doing it) but i have obtain better results using a big OBIT as bombarder (i don't know if the better results are due to a better activation of the getter or maybe a better internal outgassing due to high temperature)
Registered Member #1721
Joined: Sat Sept 27 2008, 08:44PM
Location:
Posts: 136
Hello:
Just a couple notes on Flash Xray Tubes, HV Pulse Transformers, and Glass to Metal Seals:
Tungsten wire will seal to Pyrex very well, you clean the wire, and form an oxide coating by dipping it in molten Sodium Nitrite (Meat Preservative in the US.) Then rinse and clean with distilled H2O, and dry well. This works great for up to 1-2mm size W wire.
Also glass to metal seals can be bought ready made, for this application a houskeeper seal of Copper or Kovar tube to Pyrex is great you can get these from several mm to over 10cm. Two of these and you could make your own flash X-ray tube with simple silver brazing using any non-cadmium silver brazing alloy. Here is a UK manufacturer:
As far as the cathode goes, the Russians use Tungsten foil in the shape of a washer instead of point electrodes to form the cathode. The Tungsten is between two thicker washers for heat removal.
My Russian tube is rated for 300KV, but it is normaly operated at 200-240KV, at 20PPS using a capacitor driven pulse transformer, right now its in a box. Here for all those interested check this out, so much great info on the flash x-ray tubes, and drivers:
Even if you are not into the X-ray part, check out the HV pulse transformer info on this link, some really great stuff!!! Unlike L-3 in the US, the Russians share their technical information, and do not consider everything a "Trade Secret" My feeling is the Russian cathode design is better to boot, because it can be duplicated by any skilled amature at home :)
I just wanted to post this because it gives a viable alternative to the difficult to control Marx circuit to drive flash x-ray tubes, Klystrons etc., and some really cool HV power supply info :)
Registered Member #122
Joined: Fri Feb 10 2006, 12:55PM
Location: Milano Italy
Posts: 148
Thank you for this document, will be really useful!
I imediately reply with another document, a quite old (but really useful) XRAY Nondestructive testing book, i personally photographed the pages and upload them on my webspace
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.
300kV Marx generator, driving flash x-ray tube.
