6BK4 versus 6BK4A

[Charlie]

I've often wondered just how much exposure can have an affect on a person. I'm usually using the 6BK4C/6EL4 and 3A3C... and I've spent plenty of time behind the set with the cage cover off. I feel the same way as Charles... you probably have to spend lots of time cuddled up next to the tube. It would, however, be interesting to have a meter and gauge the amount of x-rays near the back of a set.

I have an interesting tube... looks to be a HV rectifier... a 3DR3. It has a thick lead shield covering the entire tube and it's heavy! I've never seen a set using this tube... I'm assuming it was likely used in the later years... maybe late 60s / early 70s.