My 21FJ is almost on it's way!

[nasadowsk]

As long as the HV holds at 25kv and you're not hugging the CRT, radiation isn't an issue.

Seriously, does anyone know ANYBODY who got cancer from a TV set? Heck, if it were that dangerous, TV repairment would be dropping left and right.

The currents/voltages used are at the low low end of the X ray scale - IIRC, they can barely get through the faceplate or out of the cabinet.

[Chad Hauris]

Along with better X-ray protection the later HV tubes also had modifications for better performance and even physical improvements, such as the 6ME6 (6MJ6?) replacement for 6JE6C horizontal output tube having a plate cap molded into the glass like a 6BK4 so it can't twist off. I would only use 6BK4C/6EL4A and 3A3C.
Some older types of HV rectifier tubes also had problems like sagging filaments causing shorts which were corrected in later versions.