Contreras-Martinez, C. Giaccone, B. Melnychuk, O.S. Netepenko, A.V. Pischalnikov, Y.M. Posen, S. Yakovlev, V.P. JACoW Publishing Geneva, Switzerland 2673-5504 978-3-95450-234-9 10.18429/JACoW-SRF2023-WEPWB109 English 847-851 cavity photon simulation experiment SRF Contribution to a conference proceedings 2023 2023-09 https://doi.org/10.18429/JACoW-SRF2023-WEPWB109 https://jacow.org/srf2023/papers/wepwb109.pdf Two 2.6 GHz cavities are being used for dark photon search at VTS in FNAL. During testing at 2 K the cavities experience frequency detuning caused by microphonics and slow frequency drifts. The experiment requires that the two cavities have the same frequency within 5 Hz. These two cavities are equipped with frequency tuners consisting of three piezo actuators. The piezo actuators are used for fine-fast frequency tuning. A PI loop utilizing the piezos was used to maintain both cavities at the same frequency, and the results are presented.