Not sure about frequencies nor NTSC but I've transmitted from Ohio to New Zealand with no amplifier (once) using WSPRRYPI and there is also https://github.com/F

Not sure about frequencies nor NTSC but I've transmitted from Ohio to New Zealand with no amplifier (once) using WSPRRYPI and there is also https://github.com/F5OEO/rpitx https://github.com/F5OEO/rpitx