GadKo RF Modulator with S-Video, Composite Audio/Video RCA / S-Video to F-pin Coaxial, Channel 3/4 Selector GadKo is the only authorized dealer of GadKo branded products. This RF modulator will converter RCA audio/video or S-Video to F-Pin cable coax. This is great for older TVs that do not have an a S-Video or RCA inputs; but only have the cable-TV style connector.