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 #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
In a word, you must choose a valve with a very high impedance designed for EHT use, such as EHT rectifier diodes, or shunt stabiliser triodes like PD500.
Your voltage is not really high enough, either, so that very little of the X-rays produced will be able to escape the glass envelope.
Most amateur X-ray work with old EHT valves is done in the range 40 - 70kV, with currents between about 50uA and 1.5mA.
When using EHT rectifier diodes, the filament or cathode is not heated, in order to work in the very high impedance cold cathode mode when currents of the order of 50uA may be pulled through the valve.
Low energy X-rays are much the most dangerous, since they are readily absorbed by the body. Don't do these experiments if you haven't first spent your money on adequate shielding and apparatus for measuring low energy X-rays doses.
Registered Member #561
Joined: Sat Mar 03 2007, 02:46AM
Location: Adelaide Australia
Posts: 230
Harry wrote ...
In a word, you must choose a valve with a very high impedance designed for EHT use, such as EHT rectifier diodes, or shunt stabiliser triodes like PD500.
Your voltage is not really high enough, either, so that very little of the X-rays produced will be able to escape the glass envelope.
Most amateur X-ray work with old EHT valves is done in the range 40 - 70kV, with currents between about 50uA and 1.5mA.
When using EHT rectifier diodes, the filament or cathode is not heated, in order to work in the very high impedance cold cathode mode when currents of the order of 50uA may be pulled through the valve.
Low energy X-rays are much the most dangerous, since they are readily absorbed by the body. Don't do these experiments if you haven't first spent your money on adequate shielding and apparatus for measuring low energy X-rays doses.
I plan to buy some of those rolls of lead they use on roofs and solder it together into a box, then put the tube etc inside it
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
GY501 is a good one! The biggest problem at 60kV is flash over along the glass surface, so you'll get much the best results if you put the valve in a tube full of dielectric oil - remembering to include a pressure relief device, so the oil won't be forced out as it heats and expands. Oil will also cool the glass, which is a big issue at this voltage.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
I'm sure you could get by with something much cheaper, and just as good.
EHT Shunt stabilizer triodes usually give very good results - TV valves such as the European PD500 or the American 6BK4B.
Don't go throwing your money away on things advertised on flashy looking websites with re-labeled valves to impress the gullible. Buy components from ordinary electronics trade suppliers.
Registered Member #1721
Joined: Sat Sept 27 2008, 08:44PM
Location:
Posts: 136
My advice is forget the radio tubes for x-ray use. The resolutuion you can get in making images is in direct proportion to the geometric size of the x-ray source, a radio tube if it works will give you a focal spot size measured in cm, in other words fuzzy pics. Just buy an x-ray tube off ebay, or from China via an "Alibaba" search and you will have lots of fun.
Just do not forget to buy a reliable method of radiation measurment from ebay or even build one. Then use plenty of lead and distance: Cancer, sterility, and a shortend life span just is not fun.
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.
Would these tubes be suitable for Xray work?
