We present experimental results concerning the ponderomotive narrow continuum (NCp) in stimulated electromagnetic emission spectra, generated in the ionospheric F region plasma by a powerful O mode electromagnetic wave. It is found that the generation of the NCp is determined by the development of the parametric decay instability in the initial stage of the interaction of the HF pump wave with the plasma. The dependence of the NCp temporal and spectral characteristics on pump power, pump frequency, time of day, and pump schedule as well as its gyrofeatures are considered. A possible mechanism for the NCp generation is discussed.