Cosmonaut
Well-known member
I'm trying to make a decent psu for powering a pair of preamps, pultec MB1, poormans or any similar. This is my first attempt designing something for tubes, and I would like to use some spare sparts I have on the bench. Mainly a power transformer and an EZ81from and old hifi tube amp, and two 220uf,350v new caps from Tube amp doctor.
The transformer have 3 windings that were rated for 220V primary...not the actual 230VAC here in Spain. I have some measurements without load:
310-0-310
2.5-0-4.5
3.7-0-3.7
I'm learning about tube rectifiers, but something is wrong in my maths because measuring dc output from the ez81 with 7vdc on heaters, is 340vdc without filtering and load. This should be like 300vdc after that, taking in account that ez81 voltage will drop with 40mA of current, is this correct?
Well...I have made a rapid psu schematic...some help?
The transformer have 3 windings that were rated for 220V primary...not the actual 230VAC here in Spain. I have some measurements without load:
310-0-310
2.5-0-4.5
3.7-0-3.7
I'm learning about tube rectifiers, but something is wrong in my maths because measuring dc output from the ez81 with 7vdc on heaters, is 340vdc without filtering and load. This should be like 300vdc after that, taking in account that ez81 voltage will drop with 40mA of current, is this correct?
Well...I have made a rapid psu schematic...some help?