[old_tv_nut]

This has been discussed somewhere here before. I don't recall if there was a clear conclusion, but some patent issue would make the most sense. It had nothing to do with matching CRT phosphors, as this would be determined by the following matrix stages in combination with the demodulator angles and gains, so one could compensate for the other. The only practical effect on the circuit seems to be the elimination of one resistor from the input to the red adder tube.