Don wrote: <<<One thing in addition to the SSB Flattening Mod that helps for many K2s is to remove C180 (the 10 pf cap in the 2nd xtal filter circuit).>>> It is my understanding that removing C180 IS the filter flattening mod. The 120 pf cap that is added is only switched in when the OPT1 filter is selected (always for TX and when OPT1 is used for RX). Right? Lou W7DZN