  We describe a Yb-fiber based laser comb, with a focus on the relationship
between net-cavity dispersion and the frequency noise on the comb. While tuning
the net cavity dispersion from anomalous to normal, we measure the amplitude
noise (RIN), offset frequency (f_CEO) linewidth, and the resulting frequency
noise spectrum on f_CEO. We find that the laser operating at zero net-cavity
dispersion has many advantages, including an approximately 100x reduction in
free-running f_CEO linewidth and frequency noise power spectral density between
laser operation at normal and zero dispersion. In this latter regime, we
demonstrate a phase-locked f_CEO beat with low residual noise.
