A recent customer (producer of 300Bs) asked for a special VacuTrace adapter card that could analyze a pair of 300Bs or 2A3s or 45s. So I made one. It is very handy for finding exact matched pairs. The stumbling block was that each triode required its own floating center-tapped 5V filament supply in order to work. And that required adding a switched ac supply and transformers.
Anyway, I ordered a few extra boards so I can make more. If anyone desires such a beast, you can special order it for $195. Specify either 5V or 2.5V filaments.
jh
