The most advanced results in previous heating experiments at Tromsø have been obtained in thefollowing research areas: 1. (1) Generation of secondary electromagnetic waves at very, extremely and ultra low frequencies by amplitude modulated heating of the polar electrojet current. 2. (2) Stimulated Electromagnetic Emissions (SEE) and HF wave anomalous absorption; particularly for heater frequencies near harmonics of the electron gyrofrequency. 3. (3) Excitation of Langmuir turbulence. Depending on altitude with regard to the pump reflection level, Langmuir turbulence may be represented either by propagating high- and low-frequency electrostatic waves, or by localized Langmuir states (cavitons) and density depressions (cavities). Typical experimental results pertaining to these items will be presented and discussed. Other experimental results will be briefly outlined.