This paper describes a high voltage Josephson-voltage-standard-locked synthesizer (JoLoS). The instrument is based on a calibrator which is used as a sine wave generator whose output is controlled by the calculable fundamental of the stepwise sinusoidal waveform generated by a SINIS Josephson junction array. An inductive voltage divider (IVD) increases the maximum measurable voltage up to 200 V, limited by the characteristics of the IVD. Such a system, combining the versatility of a calibrator with the stability and accuracy of the Josephson voltage standard represents an improvement in ac voltage calibration up to voltages of a few hundred volts for frequencies below 1 kHz.