Using a unique Ti:LiNbO3 modulator we experimentally identify the value of the modulation chirp parameter that minimizes the transmission power penalty caused by fiber chromatic dispersion. We achieve 5 Gb/s NRZ transmission through distances of 128, 192, and 256 km of conventional fiber while incurring dispersion penalties of -0.5, 0.1, and 1.1 dB, respectively, by operating at the optimum chirp value.