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Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
thats true, but previous hazards were not known (publically) like PCB's or asbestos, until the 1970's. now at least info for toxicity is available for the public.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Grenadier wrote ...
^^ sounds like i'm getting a lecture on my quest for uranium/thorium metal.
The dose rates from U exposure are orders of magnitude lower than those of the unwanted X-ray generation being discussed here.
For example, a lump of good quality pitchblende ore will come in at 70 - 100 uSv/hr with a 3cm gap between sample and detector, (much of which activity is actually produced by Ra), while the 100kV vacuum capacitor with 10uA field emission current would produce 5 - 15 Sv/hr (assuming that lead glass is not being used) at the same distance.
Registered Member #2261
Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581
Grenadier wrote ...
Also, does anyone find it odd that we haven't heard from sparky again...?
Hilarious - or at least I hope so!
I think this meter can be used as two tubes at 50KV each max, or one tube at 100KV max.
You can't add metallic shielding near as it may cause arcing, or at least degrade performance due to parasitic capacitances.
Is there any way to tell if the tubes are made from lead glass?
So really you want a meter if you're playing with anything that may produce X-Ray - not only to protect yourself but out of responsibility towards neighbours! But what's the overall guidance for this meter based on all these figures?
Registered Member #2893
Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242
There is a way to tell. Lift them up! It should be obvious if the glass is leaded.
If not, maybe he could make a lead apron. I would still go with the lead tubes though. I doubt any parasitic capacitance from lead .5" away still separated by the glass tube would be significant. Arcing can be solved with a mylar sheet.
Registered Member #1159
Joined: Fri Dec 07 2007, 02:10AM
Location: Hudson Valley of NY State
Posts: 84
I'm still here and no, I haven't used the meter yet. I had the thing apart on the day I purchased it. It is divided into two separate compartments, the 2 HV vacuum caps, a bunch of 100 Meg ohm divider resistors, a dual wafer ceramic mode switch and a 6AL5 dual diode rectifier tube. The other compartment houses the power supply & drive circuits for the meter & scope output.
I'm going to pop it open again & draw a schematic of the high voltage compartment and, hopefully get a better idea if this thing will produce x-rays. Any way to tell (by looking) if the glass has Pb in it? The glass is not pink or brown, as usually found on used x-ray tubes.
Registered Member #1159
Joined: Fri Dec 07 2007, 02:10AM
Location: Hudson Valley of NY State
Posts: 84
In the bottom of the Vacuum cap sockets, there is a 800mmf 500 Volt doorknob cap in series with the vacuum cap. Coming up with a schematic for this is going to take a little time, the unit has 2, two wafer ceramic switches and the little wiring harness is laced.
I'm going to email Jennings and see if they can supply a manual / schematic for this unit.
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Can anyone help with info on this great find ??
