have you looked at the japanese circuit ? it is only representation , not actual circuit.
The SITh is normally ON device , the gate is to turn it OFF, it is not a standard SCR . it is triggered by a negative signal to gate , not positive .
these arent available anywhere , I havent seen one and neither has anyone on the forums .
it is also called = Feild Controlled Diode FCD .
the japanese diagram has a pulse signal representing main circuit signal , not AC rectifying
I have SCR , I cant see how they could be substituted for SITh , that is why Les Banki used mosfet IXTX20N150 1500V 20A .
Peterae donated 10 circuit boards ,Les maybe 10 boards, no one has responded on O.U.R thread, does that mean no one has even bothered? what a waste
the SITh is specifically - static INDUCTION thyristor , how does this work ? no one has any experience with one . the trigger circuit is only represented by a diode in the circuit diagram , that doesnt mean it is an actual diode only that a negative signal will pass to the gate and most likey a separate circuit
on electronics forums most techs WONT discuss HV components because of HV dangers , obviously a HV component is ony associated with a HV circuit
chances are they would have no experience with the device either