  We have measured the phase-delay and rms amplitude spectra of CygX-2 and
ScoX-1. Using EXOSAT data from the normal branch of CygX-2 we confirm earlier
(Ginga) results, showing that at an energy near 6keV there is both a minimum in
the QPO rms amplitude spectrum and a 150 degree phase jump in the
quasi-periodic oscillations (QPO) phase-delay spectrum.
  Surprisingly, using EXOSAT and Ginga data, we find no evidence for a phase
jump of this kind in the phase-delay spectrum of ScoX-1 on either the normal or
flaring branch. Upper limits (90% confidence) of 42 degrees can be set on any
phase jump in the energy range 2-10keV on the normal branch, and 88 degrees on
the flaring branch. The QPO rms amplitude spectrum of ScoX-1 increases steeply
with energy on both the normal and flaring branches. These results suggest that
the X-ray spectrum pivots about an energy of <~2keV or >~10keV or that normal
branch QPO of ScoX-1 does not have a pivoting spectrum. We discuss the
implications of these results in terms of the radiation-hydrodynamic model for
normal branch QPO.
