The radial wavenumber spectra of electrostatic fluctuations measured by Langmuir probe arrays on the KT-5C tokamak show a quasimode-like structure which results in a net radial outward propagation of the turbulent fluctuations. The power-averaged radial wavenumber is approximately constant in the core region and increases near the limiter. The radial wavenumber spectral width stays nearly constant from core to edge and is about two times greater than the poloidal wavenumber spectral width. The measured fluctuation levels and wave action fluxes are in good agreement with model predictions (Mattor N and Diamond P H 1994 Phys. Plasmas14002, Mattor N 1995 Phys. Plasmas2766) which suggest that drift wave propagation could be a source of edge turbulence.