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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment. |
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12th Jan 2023, 5:37 pm | #21 |
Heptode
Join Date: May 2014
Location: Salisbury, Wiltshire, UK.
Posts: 998
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Re: How safe are our collections?
Whilst i have seen old instruments I have never experienced the glow in the dark effect and it is pretty close to the top of my bucket list now. Must visit some aerojumbles!
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David, G4YVM. |
12th Jan 2023, 5:49 pm | #22 |
Nonode
Join Date: Nov 2015
Location: Welwyn Garden City, Hertfordshire, UK.
Posts: 2,013
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Re: How safe are our collections?
Interesting to read the wiki on Radium dials. A 1960s Westclox Big Ben was very impressive in the dark.
I had no idea that one that no longer works is probably still as radioactive as when first made. Zinc sulphide produced the light and that is what degrades not the radium. |
12th Jan 2023, 6:16 pm | #23 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,953
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Re: How safe are our collections?
The glowy dials tend to fade rather significantly with age. I've got a couple of WWII-vintage ones here which are highly 'active' but the phosphor has gone the same way as that in Magic Eyes and there's no longer any significant glow to be seen.
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I'm the Operator of my Pocket Calculator. -Kraftwerk. |
12th Jan 2023, 6:43 pm | #24 | |
Dekatron
Join Date: Aug 2003
Location: near Reading (and sometimes Torquay)
Posts: 3,086
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Re: How safe are our collections?
Quote:
BTW do not assume that alpha emitters do not emit gamma too. You get secondary nuclear reactions so the end result is often a bit of everything! Old aircraft instruments are often very radioactive. The worst I have met is the BABS indicator. If you don't have a radiation meter then you can check by shining UV light onto anything that has that characteristic brown/yellow coloured paint. If it does NOT glow then assume the worst! Later instruments had the phosphors but no radioactive material so needed a UV illuminator to work. Some of the army sets were bad too. WS62 is very bad! |
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12th Jan 2023, 6:50 pm | #25 |
Dekatron
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,385
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Re: How safe are our collections?
I'd heard that the heavy alpha emission of said paint actually fries the luminescent component into inactivity- in other words, be very wary of any brown/yellow paint that doesn't glow.
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15th Jan 2023, 7:09 pm | #26 |
Heptode
Join Date: May 2014
Location: Salisbury, Wiltshire, UK.
Posts: 998
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Re: How safe are our collections?
Eek. Maybe I will steer clear at jumbles!!
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David, G4YVM. |