$5 Shipping Weekend@ Elec Goldmine

erco

$5 flat rate shipping up to 70 lbs... stock up on those heavy items!

http://www.goldmine-elec-products.com/

There's a $5 GM tube for a Geiger counter: http://www.goldmine-elec-products.com/prodinfo.asp?number=G17365

$4 for two 5.25" speakers: http://www.goldmine-elec-products.com/prodinfo.asp?number=G18930A

GordonMcComb

erco wrote: »

There's a $5 GM tube for a Geiger counter: http://www.goldmine-elec-products.com/prodinfo.asp?number=G17365

Wonder why it's listed as detecting only gamma. I understand it not being sensitive to alpha, given the thickness of the glass and metal ends. But it should be able to do beta as well, unless there's something about the tube that further blocks it.

Anywho, nice to mention it, but even $5 is too much for a tube limited to gamma only, unless you're the Russian military building monitors for nuclear blasts, I guess. Or have been hording Cesium-137 in your living room closet.

CuriousOne

They have a lot of various goods for cheap, but unlike BGMicro, elec-goldmine does not accepts paypal and also very picky for credit cards - "we can not verify issuer of your card" I'm getting this error regardless of which card I try. When I contacted them, they said that they don't accept international card orders, but my Amex is U.S. bank issued card. So I never ordered anything with them.

localroger

I have that tube and their "ultimate giger counter kit" from last time they went on sale, for $5 and $12 respectively. The tube is small and therefore not very sensitive because it doesn't contain much gas volume for the radiation to interact with. It gives 2-3 clicks a minute at sea level background, and with a 5 gram uranium pitchblende sample next to it gives 10-15 clicks a minute.

User Name

I don't feel so badly about my cheapie United Nuclear counter - a thorium oxide mantle pretty much drives it crazy. Even a chunk of KCl increases the click rate.

It bothered me that classic Civil Defense GM counters were no longer available other than at antique mark-up prices.

GordonMcComb

User Name wrote: »

It bothered me that classic Civil Defense GM counters were no longer available other than at antique mark-up prices.

Well you'd expect that, as they ARE antiques. Even one made at the tail end of the CD era is from the 60s, which is now 50 years ago. Half a century is getting into antique territory.

Even so, not sure you can always rely on the GM tubes in these. If they have a mica window on the end -- which you want to register alpha particles -- the tube might very well be gassed out, in which case it's totally useless. (Plus, if you do get one of the really early sets, like the Radiacs, it might be one that requires oddball batteries that are nearly impossible to find, and when you do, are far too expensive for what will hopefully always be a conversation piece.)

There are still some "peanut" sized GM tubes with mica windows you can buy, but getting hard to find at the <$50 price, depending on the Nuclear Event du Jour. I remember following the Fukushima accident the price of the tubes doubled to quadrupled.

localroger

I suspect the small GM tube is meant for high flux detectors. At Chernobyl a lot of the time they had no idea what the radiation flux really was because the normal detectors were overwhelmed; the tubes can only pulse at a certain max rate, beyond which the pulses overlap and merge together. A less sensitive tube would give accurate flux estimates at higher levels. In any case it does demonstrably work, if not "impressively." I suspect you wouldn't want to be anywhere near anything that would make it give you an impressive click rate.

wass

GordonMcComb wrote: »

There are still some "peanut" sized GM tubes with mica windows you can buy, but getting hard to find at the <$50 price, depending on the Nuclear Event du Jour. I remember following the Fukushima accident the price of the tubes doubled to quadrupled.

I remember trying to buy a Heathkit Monitor 4 Geiger counter kit at the time of the Three Mile Island incident. They were back ordered 6 months. This was made for Heathkit by S.E. International who still makes these in a different form factor: http://seintl.com/radiationalert/monitor_4.html and they still use the same LND-712 tube http://www.lndinc.com/products/711/
It's a small mica-windowed tube that in my experience (I have a few of these) holds up really well, but they sell for more than $50.

GordonMcComb

localroger wrote: »

I suspect the small GM tube is meant for high flux detectors. At Chernobyl a lot of the time they had no idea what the radiation flux really was because the normal detectors were overwhelmed

Yes, I'm sure you're right that these were designed as cheap sensors for detecting levels following massive "events," namely nuclear meltdowns and fallout of fissionable material from thermonuclear weapons. You can always shield a more sensitive tube to register only gamma, but it adds cost and bulk. These appear to have been designed for some kind of mass-produced dosimeter, given the number of these tubes on eBay and the surplus markets.

On the Radiac set I mentioned earlier, the end of the wand had a metal cap (about 3/64" aluminum) that went over the window. With that cap on, it registered gamma only. The wand itself had the same thickness of aluminum tube, to prevent particles or rays from entering from the side of the tube.

GordonMcComb

wass wrote: »

I remember trying to buy a Heathkit Monitor 4 Geiger counter kit at the time of the Three Mile Island incident.

Indeed, these had a "peanut" tube, and they were very nice units. I built mine in about '89 or so, and had it until a few years ago, when I sold it to a collector. Still worked -- more a testament to Headthkit's kits, rather than my soldering skills. You're right that they sell for more than $50 these days, but I've seen a few Chinese knock-offs on eBay starting at about that. They likely only cost $5 over there. They are simple devices to manufacture.

ajward

GordonMcComb wrote: »

Well you'd expect that, as they ARE antiques. Even one made at the tail end of the CD era is from the 60s, which is now 50 years ago. Half a century is getting into antique territory.

Even so, not sure you can always rely on the GM tubes in these. If they have a mica window on the end -- which you want to register alpha particles -- the tube might very well be gassed out, in which case it's totally useless. (Plus, if you do get one of the really early sets, like the Radiacs, it might be one that requires oddball batteries that are nearly impossible to find, and when you do, are far too expensive for what will hopefully always be a conversation piece.)

There are still some "peanut" sized GM tubes with mica windows you can buy, but getting hard to find at the <$50 price, depending on the Nuclear Event du Jour. I remember following the Fukushima accident the price of the tubes doubled to quadrupled.

I bought my CDV-700 Lionel survey meter about 6 - 8 months before the Fukushima event for $21.50 on eBay. Right after that the cheapest unit I found was nearly $100. They've come down somewhat since then.
I also bought a handful of dosimeters and a charger. I clipped one of the dosimeters on my purse... gets the occasional odd look! ;-)

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