  All X-ray light curves of nova V4743 Sgr (2002), taken during and after
outburst, contain a 0.75 mHz periodic signal that can most plausibly be
interpreted as being excited by the rotation of the white dwarf in an
intermediate polar system. This interpretation faces the challenge of an
apparent multi-frequency nature of this signal in the light curves taken days
180 and 196 after outburst. We show that the multi-sine fit method, based on a
superposition of two sine functions, yields two inherently indistinguishable
solutions, i.e. the presence of two close frequencies, or a single signal with
constant frequency but variable modulation amplitude. Using a power spectrum
time map, we show that on day 180, a reduction of the modulation amplitude of
the signal coincides with a substantial overall flux decline while on day 196,
the signal was only present during the first half of the observation. Supported
by simulations, we show that such variations in amplitude can lead to false
beating that manifests itself as a multiple signal if computing a periodogram
over the full light curve. Therefore, the previously proposed double frequency
nature of both light curves was probably an artefact while we consider a single
signal with frequency equal to the white dwarf rotation as more plausible.
