Xavier,
Happy New Year!
The CL-90 is nice for keeping the startup voltage from hammering the rectifier circuit but, sadly, it doesn't help in Cathode stripping (Insert David Rose & Orchestra here).
If I have it right, the high voltage is applied after the heater is at its rated voltage. It can be done the cheap way, as I would do it, by putting a
properly rated switch in the B+ to the output tube. Maybe to the B+ to the driver too, I'm not sure.
The trick here is the
properly rated switch. Looking at Mouser most are rated at 125V, all sorts of current ratings. I found one that is rated at 250V 1A. That current is great but still not quite enough voltage.
Here are some 250V 1A results:
http://www.mouser.com/Electromechanical/Switches/Toggle-Switches/_/N-5g2j?P=1z0x3ugZ1z0z812By the way, I would have loved to watch the security guys looking at a bag full of tubes. My Post Office and mail carrier both think I'm weird sending and receiving Russian Military Surplus capacitors. Too many packages from Ukraine, I'm probably under surveillance.