Sorry. I seriously need to review the whole thread before posting - or improve my memory
...
I'm pretty sure that the TK819 I once dismantled had three rectifiers, one for the HT, one for the 24V relay control circuits, and one for the input valve heater. Of course, that doesn't mean all the machine were made that way, it could well be that they decided that there was little gain under the circumstances for a DC heater supply.
Hm. Or else I'm confusing this with certain early Tandberg models, like the 3B, which has the same winding for the heaters for all valves, yet the EF804 input valve is in fact rectified and smoothed.