Reflectometer measurements of electron density perturbations produced by modulation of the gas feed are used to measure the electron source distribution and benchmark Monte Carlo neutral transport calculations. The penetration depth of the source is less than 5% of the plasma radius in medium density plasmas ((ne) approximately 2*1019 m-3). An analysis of the temporal evolution of the electron flux calculated using the measured source yields the diffusion coefficient, De, and the pinch velocity, Vp. The radial profiles and parametric dependences of these particle transport coefficients are studied in Ohmic and L-mode regimes.