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Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
UNDER CONSTRUCTION
2X2A Test Rig
The red inner wire is RS Components 25kV EHT cable. The thick outer insulation is silicone rubber. The black casing is a 35mm film can, a tight push fit onto the 2X2A base.
This is Code 4 - meaning 1.8mm thick - rolled lead sheet.
According to the British Sheet Lead Association: "In the UK, rolled lead sheet is the only lead sheet for building made to a British Standard – BSEN 12588:2006 Rolled Lead Sheet for Building Purposes. This specifies thickness and chemical composition to produce a consistent microstructure, which provides the required resistance to creep and thermal fatigue. The standard provides guidelines for length and width and stipulates that the sheet shall be free from inclusions and laminations. For building purposes, rolled lead sheet is available in Codes 3-8 thickness range 1.32mm to 3.55mm (+5% measured at any one point) and from widths 150mm to 2400mm."
Codes 3 and 4 are the only thicknesses I've ever seen offered for sale in builders' merchants, but I'm sure the dedicated rolled lead enthusiast could winkle out some Code 8 - the backbreaking 3.55mm - and carry it off on a forklift trolley to great applause!
The attenuation of 50keV X-ray photons (my maximum) by 1.8mm Pb sheet is 7.6E-8
I used Araldite Industrial Slow Epoxy adhesive to glue the lead sheet to the GRP form. I chose a slow setting glue to give me the longest working time while I positioned the clamps.
You can never have too many clamps!
I used self-adhesive aluminium tape as an environmental barrier over the Pb sheet, and used the back of a wooden spoon as a burnisher to reduce wrinkles and blisters of trapped air.
I turned the raw edge of the cut lead over onto the top of the form by gentle tapping with a rubber mallet.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Patrick wrote ...
You guys are building such cool stuff !!! (Though, I hope you all dont die.) I wish I understood more of the radioactive phyics stuff.
Is that fat red wire HV+ ? where is your ground?
EDIT: Proud Mary I see you too are a user of the aluminum tape !
You can't have too much metal tape! I also have rolls of stainless steel, copper, and even self-adhesive lead.
Here, I'm using the aluminium tape as an environmental barrier over the 1.8mm Pb sheet. I used the back of the wooden spoon to burnish the aluminium and get out all the wrinkles and air bubbles out of it.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Patrick wrote ...
where is your ground to complement that fat red wire?
It exits the shield through a small hole almost diametrically opposite to the HV- window. But for the small voltage drop across the moving coil meter, it is effectively at Earth potential.
Registered Member #1938
Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 701
I wonder how happy would be the 2X2 tube to get connected to the 140KV supply that I've put together today: . Oil would be needed because the tube's so short
I've got a new lot of rectifiers myself, I'll be testing them soon:
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
I have two small wire-ended EHT rectifiers that I thought I would try tomorrow afternoon - they are a Mullard EY51 and a Brimar R16, both 17kV PIV from the days of small black-and-white televisions.
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Vacuum Rectifiers X-rays report
