A low current loss ballast operates a high intensity discharge lamp with or without radioactive krypton. A by-pass capacitor in conjunction with a resonant strike circuit limits high frequency ripple applied to a lamp during continuing operation. Different resistor combinations are connected to drive dual buck converters of the ballast. One combination is used for high frequency operation for striking. Another combination is used during low frequency operation to limit current loss. In a strike mode of operation, combinations of signals at a resonant frequency for striking and subharmonic frequencies are applied to a resonant circuit. The signals at the subharmonic have less than a 50% duty cycle.