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Radioactive Mineral Sample Prospecting Equipment - Advice Sought

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IntraWinding

Sat May 08 2010, 02:31PM

Registered Member #2261 Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581

Thanks, although now I'm thinking an air cooled version would be better, requiring just the fan.
I don't suppose you'd know of a small good air cooled one going cheap?

Proud Mary

Sat May 08 2010, 04:26PM

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

IntraWinding wrote ...

Thanks, although now I'm thinking an air cooled version would be better, requiring just the fan.
I don't suppose you'd know of a small good air cooled one going cheap?

You could try posting on The Belljar forum.

I have two air-cooled Edwards Speedivac 11cc diff pumps with built in fans, both in need of a radical overhaul, and will consider lending you one when I've got both up and running. Don't hold your breath waiting, though, as we have nothing quite so immediate as maÃ±ana here...

IntraWinding

Sat May 08 2010, 10:36PM

Registered Member #2261 Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581

Thanks again but I'll go for that water cooled one after all if that's ok - it'll be nice to have it there ready for when I finally get around to using it, and I already have water cooling gear or long silicone hoses to suit it...

I've been a fan of The Bell Jar for years. I'm hoping one day to see a copy of the back issues on eBay...

A pet vacuum project I have on the (overcrowded) back burner is Peltier stack cooled cold trap. I picked up a Quickfit cold trap years ago and have pumps and radiators from when I used to water cool my PC (home made copper cooling blocks - I was particularly proud of my jet impingement CPU cooler).

It wouldn't be as cold as liquid nitrogen, but then I don't have any of that, so I can't complain.

With careful insulation the heat load should be very low as it'll be basically a case of cooling the inside of a Thermos flask so with a suitably designed stack it should get near to the minimum obtainable.

Alan

Proud Mary

Sat May 08 2010, 11:04PM

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

Nowadays, with 704 or 705 silicone fluids you don't really need cold traps for general work in the way that was necessary with hydrocarbon oils.

I'd have thought the water-cooled pump you're looking at would do you very well indeed to start off with. A Penning, or Pirani, or Edwards ionisation gauge head and control unit would come in handy too, so you know what is going on with your vacuum. They aren't offered for sale very often.

IntraWinding

Sun May 09 2010, 01:11PM

Registered Member #2261 Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581

I wonder my bottle of silicone photocopier fuser oil would work!

I have a working Edwards "PRE 10K" Pirani Gauge & Pirani 501 meter similar to this pair

except my meter is like this

. It's lack of calibration is annoying. I can tell there is a significant improvement however when I add my freshly baked Forline trap, like the one on the left here:

I also have an 'inverted magnetron gauge' which I stripped down and cleaned of its carbon deposits, but have never tested. Worryingly it has a socket that fits a computer network cable.
It's marked:

Edwards
Active Gauge
AIM-PL-PODULE
P. No : D14549800

Mine is almost identical to this one on eBay (at a huge price) except where mine has PODULE it has NW25 and the labling on mine looks like an older design.

But I cant find any technical info on interfacing to the AIM-PL. I've just emailed Edwards and the eBay seller. Perhaps I should ask at The Bell Jar, unless you have any ideas?

This is close, for the AIM-S & AIM-X

and there are manuals for the AIM-X & AIM-XL via here

I guess mine is probably wired in the same way, but I won't be happy until I find the manual

But I suppose I should count myself lucky to have it at all as it seems to be quite valuable and I got it cheap in a box full of vacuum bits...

Alan

Proud Mary

Sun May 09 2010, 02:10PM

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

IntraWinding wrote ...

I wonder my bottle of silicone photocopier fuser oil would work!

I've been thinking very much along those lines myself, Alan. Not long ago, Les discovered that some super-costly vacuum epoxy had exactly the same ingredients as a common or garden variety, and I wouldn't be surprised if the same turned out to be true of vacuum fluids. I guess it depends on what you have in mind. At the mo, my main thing is hollow cathode Grimm discharges, and photons too feeble to travel in air, and you don't need 10 to the minus zillion Torr for that at all, nor do I need to make a religion out of slow leaks, 'cos I can keep the pump running for the duration of the experiment.

IntraWinding wrote ...

I have a working Edwards "PRE 10K" Pirani Gauge & Pirani 501 meter similar to this pair

except my meter is like this

. It's lack of calibration is annoying. I can tell there is a significant improvement however when I add my freshly baked Forline trap, like the one on the left here:

My two Pirani gauges are so old that the only reason they exist today is because they were allowed aboard the Ark by Noah, who didn't have too much up top, and mistook them for a pair of carnivorous fish.

What I do have is a complete Penning, and a complete Pirani control and read-out thingamy, which are so old and simple that they can easily be reverse-engineered to produce some clones.

IntraWinding wrote ...

I also have an 'inverted magnetron gauge' which I stripped down and cleaned of its carbon deposits, but have never tested. Worryingly it has a socket that fits a computer network cable.
It's marked:

Edwards
Active Gauge
AIM-PL-PODULE
P. No : D14549800
S. No : 08F50433025

Mine is almost identical to this one on eBay (at a huge price) except where mine has PODULE it has NW25 and the labling on mine looks like an older design.

But I cant find any technical info on interfacing to the AIM-PL. I've just emailed Edwards and the eBay seller. Perhaps I should ask at The Bell Jar, unless you have any ideas? Really I'd prefer an analogue output.

I should think it is an analogue output, Alan, but one designed to mate up with an A-D converter. Earlier generations of Edwards kit used DIN plugs to save a few pennies on government contracts I suppose, when screw up circular multiway connectors would have been ten times more reliable. One Edwards gauge I have outputs through a crappy TV-type coax socket - so quite predictably the centre pin has gone all wonky, and I shall replace it with a good quality BNC chassis mounting socket with a captive cap.

Is this your magnetron gauge, Alan, with the 8 way FCC68 (RJ45) socket? 2V - 10V output on Pin 3, so no digital horror?

It'll be good for you if it is, because you won't have to brew up an EHT supply for it.

IntraWinding

Sun May 09 2010, 09:26PM

Registered Member #2261 Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581

Proud Mary wrote ...

Is this your magnetron gauge, Alan, with the 8 way FCC68 (RJ45) socket? 2V - 10V output on Pin 3, so no digital horror?

It'll be good for you if it is, because you won't have to brew up an EHT supply for it.

I think it's in the same range. It has the same connector, so definitely no HT input. It was intended by Edwards to plug into something like this Edwards AGC Active Gauge Controller

The two at your link differ between one another in terms of hardest vacuum readable and linearity. I suspect mine will turn out to be as good as the lesser of those two, or slightly worse, but still very useful. But I'll feel much happier having the manual.

Proud Mary

Sun May 09 2010, 10:46PM

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

That control-display unit doesn't look much like my old antiques, and it doesn't look cheap either.

"Rapid tube replacement without pre-calibration" says the blurb. So they're s'posed to work straight out of the box with the Edwards costly read-out at the end of the cable.

Both variants start at 10E-2 Torr which corresponds to 10V on the very useful graph, and there's a crossover point when both types will produce the same voltage (~6V5) for the same pressure(~10E-5 Torr), whereupon they start to diverge again. Even if you don't succeed in identifying which type yours is, or if its pre-calibration is still any good, you'll still have some idea what is going on! Your set-up will be like a stopped clock that tells exactly the right time twice a day!

As with my Pirani and Penning gauges, the ultimate point of reference has to be the McLeod gauge, of blue gums, loose teeth and
hair-falling- out-in-clumpfuls fame.

For the time being, I say look after the vacuum, and the gauges will look after themselves. Without accurate points of calibration, you can still make relative readings, as to more or less, which is a lot better than a poke in the eye with a burnt stick!

There's a good crib sheet about the accuracy of the different sorts of gauges here:

IntraWinding

Mon May 10 2010, 05:53AM

Registered Member #2261 Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581

Yes, I do get hung up on accuracy when it isn't necessarily that important.
I'll build my own display for this with a mechanical meter and scale knocked up in Photoshop.
I prefer a relaxed (non-toxic) atmosphere - I don't mind immediate risks that I can take on, deal with and leave behind, either having avoided or knowing I screwed up, but insidious cumulative brain wrecking poisons are just a downer, so I'll skip the McLeod gauge option. Besides, it relies on the mercury being ultra pure.

What's all that "hollow cathode Grimm discharges, and photons too feeble to travel in air" stuff about then?

Proud Mary

Mon May 10 2010, 09:00AM

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

IntraWinding wrote ...

Yes, I do get hung up on accuracy when it isn't necessarily that important.

All those decimal places on digital displays create an illusion of accuracy which may not always be there.

IntraWinding wrote ...

I'll build my own display for this with a mechanical meter and scale knocked up in Photoshop.

Good man! There's clearly a cable driver in that head unit, so you won't have much to do except put your moving coil voltmeter on pin 3.

Nothing so simple with my vintage Penning gauge control box. On the back is a calibration module about the size of a box of matches, which plugs into an international octal socket. "Use only with head of serial number 1370," it says. Each head unit has its own unique plug-in calibration module, and none of my Penning heads matches the only module that I have. So I shall have to tinker with it - tinkering being my true vocation.

Things are much better with my 2-channel Pirani control box, which isn't faddy about which head units I plug into it.

IntraWinding wrote ...

I prefer a relaxed (non-toxic) atmosphere - I don't mind immediate risks that I can take on, deal with and leave behind, either having avoided or knowing I screwed up, but insidious cumulative brain wrecking poisons are just a downer, so I'll skip the McLeod gauge option. Besides, it relies on the mercury being ultra pure.

Ever since I started working with Hg, I've not been certain whether I'm a late developer, or simply entering my second childhood early

- I wouldn't keep it in the house, or sluice residues down the drain either.

IntraWinding wrote ...

What's all that "hollow cathode Grimm discharges, and photons too feeble to travel in air" stuff about then?

There is life below 5keV, Alan, but not as we know it!

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