c0pperdragon on their GitHub project page has released a new PCB design for a simple Commodore 64 Video Enhancement. While their other main piece to this project is for a video enhancement that will utilize component video. This is just a cheaper analog option replacing the RF modulator so users can improve the original S-Video and Composite video signal. Links below to check out this project.
LINKS: https://github.com/c0pperdragon/C64-Video-Enhancement/tree/master/analog_only