to be honest with this module, and this valve the heater filament is actually 6.3VAC which isn’t available in just a modular power connection. so 12v DC seemed quite fitting bearing in mind its a full wave. -12v generally has less current consumption so figured to pop the heater on that side of the power supply. however I found when I built this module the first time without a resistor is generated a bit of hum in other modules, a try 27r resistor eradicated the issue. I was going too improve this to get more glow out of the tube itself in this iteration but after fiddling with the circuit in January I wasn’t happy how it was turning out with the mods I was doing to it, so I made the decision to basically make it exactly the same as the one I had in my modular I was looking to replace.
its not the right way of doing it but it works, and I can show for a module that was used nearly daily for about 2 and a half 3 years and still works fine doing its thing I figured its fine.