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The magnitude of sudden phase and amplitude anomalies (SPA and SAA) on the Novosibirsk-Yakutsk, KrasnodarYakutsk and Khabarovsk-Yakutsk VLF radio propagation paths during 2009-2016 as a function of the solar X-ray flux are considered. From the minimum (2009-2010) to the maximum (2014) in 11-year solar cycle activity (SA), the SPA sensitivity to a solar flare X-ray flux decreases in winter. For the signal Novosibirsk: the slope of the linear model is 11.9 (for 2009-2010) and 13.1 (for 2014), the initial offset is 74.7 (2009-2010) and 78.7 (2014). For the Khabarovsk signal: the slope is 9.9 (2009-2010) and 15.3 (2014), the offset is 71.1 (2009-2010) and 94.2 (2014). The decrease in SPA sensitivity is noted due to an increase of the ionizing background flux. The decrease sensitivity of Krasnodar signal SPA was not detected due to large phase fluctuations. There is an increase in the VLF amplitude with increasing X-ray radiation flux in winter. In the summer, the saturation of Novosibirsk signal sudden amplitude anomaly occurs for the solar flare ionization flux 10-5 W/m2 . In summer, the amplitude of the Khabarovsk signal with an excess of the solar flare ionization flux of 3×10-6 W/m2 becomes less than the background value.
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