[Adam]

I've been busy the past week, but now that I finally have some time to think about this … I know how the bridge rectifier works: that when the AC flows in one direction it goes through one pair of diodes, the opposite direction it goes through the other pair of diodes, and you get a full-wave rectifier instead of just half. I see that that .1 uF cap would filter the AC on the heater string. But I don't understand where the DC on the heater string comes from, or how the amount of AC vs DC voltage on the heater line changes with the tube position. (I would think that the total voltage drop across each tube would depend only on the resistance the filament, and would not change if its position were changed)