  In this paper, we report all results obtained with a fiber scrambler on the
Hamilton spectrograph at Lick Observatory. We demonstrate an improvement in the
stability of the instrumental profile using this fiber scrambler. Additionally,
we present data obtained with a double scrambler that further improves the
stability of the instrument by a factor 2. These results show that errors
related to the coupling between the telescope and the spectrograph are the
dominant source of instrumental profile variability at Lick Observatory. In
particular, we show a strong correlation between instrumental profile
variations and hour angle, most likely due to pointing-dependent illumination
of the spectrograph optics.
