  We present an analysis of the long RXTE observation of the Seyfert~1 galaxy
MCG-6-30-15, taken in July 1997. Our results show that the behaviour is
complicated. We find clear evidence from colour ratios and direct spectral
fitting that changes to the intrinsic photon index are taking place. Spectral
hardening is evident during periods of diminished intensity; in particular, a
general trend for harder spectra is seen in the period following the hardest
RXTE flare. Flux-correlated studies further show that the 3-10 keV photon index
steepens while that in the 10-20 keV band, flattens with flux. The largest
changes come from the spectral index below 10keV; however, changes in the
intrinsic power law slope, and reflection both contribute in varying degrees to
the overall spectral variability. We find that the iron line flux is consistent
with being constant over large time intervals on the order of days (although
the ASCA and RXTE spectra show that $F_{K\alpha}$ changes on shorter time
intervals of order < 10ks), and equivalent width which anticorrelates with the
continuum flux, and reflection fraction. Flux-correlated studies point at
possible ionization signatures, while detailed spectral analysis of short time
intervals surrounding flare events hint tentatively at observed spectral
responses to the flare. We present a simple model for partial ionization where
the bulk of the variability comes from within 6r_g. Temporal analysis further
provides evidence for possible time (< 1000s) and phase (phi~0.6 rad) lags.
Finally, we report an apparent break in the power density spectrum (~ 4-5 x
10^{-6}Hz) and a possible 33 hr period. Estimates for the mass of the black
hole in MCG-6-30-15 are discussed in the context of spectral and temporal
findings.
