My CTC-16XL Project.

[Yamamaya42]

In regard to protecting the FBT, given that there is near zero chance of finding one for a CTC-16X series, going from the starting point that it seemed in excellent condition to start with, ( no wax loss seen, or arcing traces ), it seems I was lucky getting this.
From all the many threads I have read, the most important seems to be HOT (6JE6A) cathode current, & keeping it as low as one can w/o losing function ( below 200ma).
To aid in this, converting the focus to solid state helps, as it removes the draw from it's heater winding.

What also is said to help is more ventilation for the HV cage, to allow any generated heat from the FBT/ HV RECT to escape more easily , this is done by adding holes in key places and forced air via fans, perhaps on the back.

At this point, I can't think of anything more to do to try and protect the FBT, as shown in the thermal scan before, w/o the back on that has the fans on it, the HV on mine is very cold after an hour running.

https://imgur.com/3hZnlmW

What can't be seen there, and this kind of surprised me, is I drilled 4 large holes in the front of the HV cage, and there is no heat at all seen coming from them, I did not expect things in there to be so cool as not to be able to see the holes on infa red.