Interesting... these are RADIO ACTIVE ?!
![Scared :scared:](https://www.eevblog.com/forum/Smileys/default/scared.gif)
"mildly" so, they say, still !!! ![Confused :-//](https://www.eevblog.com/forum/Smileys/default/confused0024.gif)
I understand everything on this planet is radioactive to some degree, including our own bodies, but adding the stuff purposefully in something a mundane as a freaking light bulb, wow... I hope at least they got thee dosage right and it's indeed "mild" enough to be safe... but what was the definition orf "mild" compared to today's standards ?! Who knows...
Looks like back in the day radioactive stuff was very fashionable
I don't know about the stated "dark effect" in the catalog page but back then radioactive elements were added to get the aluminium alloys of the day to the required tensile strengths in some applications.
Might be the same here where they needed to spice up the Tungsten filament to whatever spec they desired.
How I know that? Well, as a turbojet mechanic in training I'm being trained or have trained with an GE J79-17A (F4F Phantom II) and Orenda 14 (Canadair F86 subvariant) engine and those feature cast aluminium casings containing several percent of Thorium. They're harmless know though we have to be careful with these so we don't produce any chips or dust one could breathe in.
The radioactive additives are for neon glow lamps used in this & other test gear,
not filament lamps. Neither the GE book or Signalite book mention what the radioactive isotope used is.
But I have seen larger voltage reference glow tubes (eg. OA2) that are labelled as containing a tiny amount of Krypton.
David