Yao, Z.Y. Kolb, P. Laxdal, R.E. JACoW Geneva, Switzerland A significant issue in low beta resonators is medium field Q-slope (MFQS) at 4K that in some cases has resulted in projects choosing to operate low frequency cavities at 2K. Recent measurements have been done on QWR (80MHz) and HWR (160MHz) cavities at TRIUMF to study the MFQS of Low Beta Resonators. Quality factor data taken in cooling from 4K to 2K is used to separate the rf surface resistance into BCS and residual components for different surface treatments. These measurements shed light on the mechanisms behind the field dependence in the rf surface resistance.