HHFW RF power delivered to the core plasma of NSTX is strongly reduced as the launched wavelength is increased - for B=4.5kG, heating is ∼1/2 as effective at k=-7m-1 as at 14m-1 and ∼1/10 as effective at -3m-1. Measured edge ion heating, attributable to parametric decay (PDI), increases with wavelength but not fast enough to account for the observed power loss. Surface fast waves (FW) may enhance both PDI and also losses in sheaths and structures around the machine - FW fields propagate closer to the wall with decreasing B and k∥ (onset n e∝B×k∥2). A dramatic increase in core heating efficiency is observed at -7m-1 when B is increased to 5.5 kG - central Te near 4 keV at PRF=2MW. Also, the PDI losses are a weak function of B and k∥, whereas the far-field RF poloidal magnetic field (at 5.5 kG) increases a factor of ∼3 when k ∥ is reduced from 14m-1 to -3m-1, suggesting a large increase in wall/sheath power loss and a major effect of surface fast waves on edge losses. © 2007 American Institute of Physics.