Yang, Y. Baričevič, B. Byrd, J.M. Fystro, G.I. Meyer, D.A. Nassiri, A. Pietryla, A.F. Smith, T.L. Sun, Y. JACoW Publishing Geneva, Switzerland 2226-0366 978-3-95450-215-8 10.18429/JACoW-LINAC2022-THPOPA23 English 792-794 linac LLRF klystron operation controls Contribution to a conference proceedings 2022 2022-09 https://doi.org/10.18429/JACoW-LINAC2022-THPOPA23 https://jacow.org/linac2022/papers/thpopa23.pdf The current analog LLRF systems which have supported the APS linac operation for over 25 years, will be replaced with digital LLRF systems utilizing the latest commercially available electronics technology. A customized LLRF system has been developed as the next-generation APS linac controller. Two systems have been manufactured and delivered to the APS. On-site tests demonstrated they met the APS linac operation requirements with the first system expected to be integrated into APS linac operation this year.