"Dave H." wrote:

Most valves (out of a nold Telly etc) have thoriated tungsten cathodes in
'em, which might be enough of a source? I'd guess that the electron gun in a
tube might be a source, too. IIRC, camping gas lamp mantles are thoriated,
TAAW.

Thanks. I guess I could go into the local electonics shack and ask if
they've got anyold valves that they were going to throw away.

I used to work in a big transmitter cabin which had fibre-optics for the
control gear, and wondered why we had to replace them every few years, only
to be told "Oh, the radiation from the TWT [1] makes them go cloudy..." 0

Jeez.

--
John