The first results from the program HOTRAY for ray tracing electrostatic and electromagnetic waves in a hot plasma are presented. The calculations are applied to the linear mode-conversion window theory for the generation of Terrestrial Myriametric Radiation corresponding to a specific event observed by the DE-1 satellite. Results show that backward propagating electrostatic waves can refract in a density gradient normal to the magnetic field to become Z-mode waves and can have access to the radio window. During propagation the waves remain minimally damped. Variations of approximately 0.01¿ in the initial wave normal angle &psgr; can result in a large difference in the transmitted wave intensities. However, if such variations do occur, waves from different locations can still access the radio window so that energy transfer to the conversion point remains efficient. Strong refraction of electrostatic waves at latitudes >1¿ show that the magnetic equator is the preferred location for mode conversion to take place. ¿ American Geophysical Union 1988