It is ~$11 more for a solid filament specific TX from Radio Shack. The 12.6-0-12.6/2A would get run full wave with a pair of Schottky diodes and CRC filtering to deliver the 12.6 VDC to the filaments at a half an amp. RCRC might be better as the charging events( spikes of current delivery to the capacitor at the peaks of the voltage wave-form ) of the first capacitor can spread themselves around and make things a bit dirty.

I have tried AC on 5687 and while I get close to tolerable hum it never quite got quiet enough. It is 4x the current delivered to a 12AU7 and that valve is just able to run a llinestage on AC( with a lot of care, see the Bottlehead efforts in that arena ).

I had specified two heater windings to offer maximum flexibility for rectifier choices, not to run the ampifier's DC filament supply. I am sorry if this was not clear before. It saves a bunch of headache to keep the filament and B+ DC supplies as seperate as is possible.
regards,
Douglas

I appreciate the offer of MOSFETS, IFF when the project is done, there are extras, I'll still want to pay. Get extras anyway, it is possible that one or three get destroyed by accident and getting another order together would be troublesome. DN2540N5 are an item I do not like to be without, I have an adequate supply for my current needs.
regards,
Douglas

I appreciate the offer of MOSFETS, IFF when the project is done, there are extras, I'll still want to pay. Get extras anyway, it is possible that one or three get destroyed by accident and getting another order together would be troublesome. DN2540N5 are an item I do not like to be without, I have an adequate supply for my current needs.
regards,
Douglas