Hey-Hey!!!,
Just remember, it is easy to question something like this super 2A3. I'd rather see a valve that doesn't have to ride on any other valve's use. Perhaps one which could be sub'd with minimal or no fuss...but one that enough different to require another name.A 40W 2A3 is the 300B, but with lower voltage filament. This bigger tube should have a bigger filament, perhaps even a thoriated one...:) Imagine a 2A3-ish that glowed yellow/white like an 845, all at 2.5 V. Now that would be one HD filament, no?
cheers,
Douglas