I concur. I have 2.8, 2.1 and 1.8 KHz 8 pole roofing filters in my K3S. I made over 8500 SSB QSOs last month and I used the 2.1 KHz roofing filter for all of them. John KK9A Jim Brown K9YC wrote: I tried that and didn't like the result. I prefer 2.1 kHz 8 pole 73, Jim K9YC