Wavelength accuracy and stability are key requirements for differential absorption lidar (DIAL). We present a control and timing design for the dual-stabilized cw master lasers in a pulsed master-oscillator power-amplifier configuration, which forms a robust low-cost water-vapor DIAL transmitter system. This design operates at $823\mathrm{nm}$ for water-vapor spectroscopy using Fabry–Perot-type laser diodes. However, the techniques described could be applied to other laser technologies at other wavelengths. The system can be extended with additional off-line or side-line wavelengths. The on-line master laser is locked to the center of a water absorption line, while the beat frequency between the on-line and the off-line is locked to $16\mathrm{GHz}$ using only a bandpass microwave filter and low-frequency electronics. Optical frequency stabilities of the order of $1\mathrm{MHz}$ are achieved.