This paper includes a description of a prototype DAC plus Vector Modulator board and process of starting the system up. The idea of vector modulation and its limitations are also discussed below. The board is a part of the LLRF system, which provides the control of a superconductive accelerator and free electron laser. The article describes the hardware project implementation of the system. The PCB structure of the designed board is presented. New ideas of improvements for the next version of high power klystron driver are discussed. Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/16/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx Proc. of SPIE Vol. 6937 69370K-2 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/16/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx