RGB-to-Colour difference converter

The circuit diagram shows two LT1398’s from Linear Technology used to create buffered colour-difference signals from RGB (red-green-blue) inputs. In this application, the R input arrives via 75-? coax. It is routed to the non-inverting input of amplifier IC1a and to 1.07-k? resistor, R8. There is also an 80.6-? termination resistor R11, which yields a 75-? input impedance RGB-to-Colour difference converter 026 at the R input when considered in parallel with R8.