On 10/21/2020 4:49 AM, Conrad PA5Y wrote: > So given all that I am beginning to wonder if the problem is due to filter ripple in the standard K3S 2.7kHz filter? Many years ago, when I replaced stock 2.7kHz filters with 2.8 kHz filters in both my rigs, it significantly reduced the incidental AM I was seeing on RTTY. 73, Jim K9YC