Computer s-video coaxial TV
Computer s-video rca TV
(Not to mention whatever processes the TV goes through with RCA or Coaxial inputs)
When I was at Fry's today and purchased my RF Modulator I didn't see any converter that took s-video input and gave RCA output. Even if I did, I might still be making the same purchase. (At my church, for instance, some of the TV's don't even take RCA inputs) But I will have my eyes open. Fry's has a liberal return policy.