[ARC5] VR Tubes

[WA5CAB at cs.com]

VR tubes contain a small amount of a radioactive gas (radon if I recall 
correctly but I won't swear to it) to provide a few photons at all times to 
help initiate the ionization event.  That's the reason for all of the radiation 
warning trefoils on the added page in the front of most 1950's or 60's 
vintagae TM 11's, and added to the outside of the tube boxes.

Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480