There is a take-off on the mod that uses a 100 pf cap instead of 120 pf that the original mod describes. Also the mod with the 100 pf adds a 5.6K resistor across pins one and two of U11. I presume that this resistor is for terminating the filter. Is it really needed? If so, why not terminate the original mod the same way? Regards, Helm. WB2ADT