  The Y.T. Lee Array for Microwave Background Anisotropy (AMiBA) started
scientific operation in early 2007. This work describes the optimization of the
system performance for the measurements of the Sunyaev-Zel'dovich effect for
six massive galaxy clusters at redshifts $0.09 - 0.32$. We achieved a point
source sensitivity of $63\pm 7$ mJy with the seven 0.6m dishes in 1 hour of
on-source integration in 2-patch differencing observations. We measured and
compensated for the delays between the antennas of our platform-mounted
interferometer. Beam switching was used to cancel instrumental instabilities
and ground pick up. Total power and phase stability were good on time scales of
hours, and the system was shown to integrate down on equivalent timescales of
300 hours per baseline/correlation, or about 10 hours for the entire array.
While the broadband correlator leads to good sensitivity, the small number of
lags in the correlator resulted in poorly measured bandpass response. We
corrected for this by using external calibrators (Jupiter and Saturn). Using
Jupiter as the flux standard, we measured the disk brightness temperature of
Saturn to be $149^{+5}_{-12}$ K.
