[R-390] Radiation VR tubes

[Charles Steinmetz]

According to Bell Labs scientists James Gewartowski and Hugh Watson, 
the electrodes of cold-cathode VR tubes are usually 
Molybdenum.  Krypton 85 or Radium is often used to speed up the time 
it takes for the tube to begin conducting (what Gewartowski and 
Watson called a "radioactive keep-alive"), by creating a permanent 
supply of ions in the fill gas.  (There are other "keep-alive" 
methods, but the radioactive method works well and is the simplest.)

Best regards,

Charles



Chris wrote:

>Thorium on the cathode at the least, but all sorts of nasty stuff 
>can be found in different tubes-  Radium included.
>
>There are several possibilities listed here-
>
>http://www.orau.org/ptp/collection/consumer%20products/electrontubes.htm
>
>Regards,
>
>Chris
>
>
>
>Steve  wrote:
>
> > I knew this person that purchased a sleeve of VR tubes at a 
> hamfest. Some of the tubes were
> >
> > marked with the radiation symbol. Apparently the radioactivity 
> was to lower the strike voltage.
> >
> > What is the radioactive element inside?
> >
> > Steve N8YE