  Recently published ALMA observations suggest the presence of 20 ppb PH$_3$ in
the upper clouds of Venus. This is an unexpected result, as PH$_3$ does not
have a readily apparent source and should be rapidly photochemically destroyed
according to our current understanding of Venus atmospheric chemistry. While
the reported PH$_3$ spectral line at 266.94 GHz is nearly co-located with an
SO$_2$ spectral line, the non-detection of stronger SO$_2$ lines in the
wideband ALMA data is used to rule out SO$_2$ as the origin of the feature. We
present a reassessment of wideband and narrowband datasets derived from these
ALMA observations. The ALMA observations are re-reduced following both the
initial and revised calibration procedures discussed by the authors of the
original study. We also investigate the phenomenon of apparent spectral line
dilution over varying spatial scales resulting from the ALMA antenna
configuration. A 266.94 GHz spectral feature is apparent in the narrowband data
using the initial calibration procedures, but this same feature can not be
identified following calibration revisions. The feature is also not reproduced
in the wideband data. While the SO$_2$ spectral line is not observed at 257.54
GHz in the ALMA wideband data, our dilution simulations suggest that SO$_2$
abundances greater than the previously suggested 10 ppb limit would also not be
detected by ALMA. Additional millimeter, sub-millimeter, and infrared
observations of Venus should be undertaken to further investigate the
possibility of PH$_3$ in the Venus atmosphere.
