Thanks, Chad. Now we can continue this without hoggin Tim's thread on his new find!
Back to the tubes... I too have wondered about those regulator tubes that darken with use. I've seen many. If it's been hit with heavy duty x-rays, this doesn't necessarily mean the tube has exhausted it's ability to do it's job well?
Stuff like this makes me also wonder just how badly we are being exposed to these rays as we're working on sets with the backs and covers off. We probably spend a fair amount of time back there with the set operating and checking for voltages, looking for intermittent connections, etc.
Concerning the above 3DR3 lead shielded tube, I found a comment about it in an old style bulletin board from 6 years ago. Here's what someone said...
3DR3 is a lead oxide shielded HV rectifier for a large old black and white
t.v. and it only is good for a max of about 40mA I'm pretty sure with peak
current of 120mA or so.
That I can think of, i've never seen a set with this tube. It would be interesting to find one with it.