We present the results of the analysis of the measurements data of amplitudes and phases of signals from GQD (19.58 kHz) and GBZ (22.1 kHz) VLF transmitters in the geophysical observatory of IDG RAS “Mikhnevo” (GO MIK) to assess the impact of solar flares of different classes that occurred in June 2014 on the height profile of the electronic concentration $Ne$ in the lower ionosphere. The use of two-channel data from the GOES satellite (0.05-0.4 nm and 0.1-0.8 nm) allowed us to estimate the fluxes of X-rays in harder spectral ranges. The analysis of the dynamics of the $Ne$ height profile and X-ray fluxes in different wavelength ranges allowed us to estimate the ionization and recombination rates and determine the spectral ranges of radiation that have the greatest influence on the dynamics of the electron concentration at considered heights.