So.... is it now agreed that using a diode in a half-wave circuit yields the necessary nominal 12 volts needed for the 6BA6 VFO and BFO filaments in series? That seems to be the conclusion from Cecil's posting and his formula's: Diode half-wave circuit = ((25 volts input x 1.404 peak)/2)x.707 = 12.4 volts with 25 volts input -tom