The Yaesu 817, 857, 897 have their filters set up for a 1000Hz center frequency. Both the LPF and the HPF have 1000Hz as a limit of adjustment. I'm running 1000 - 1850Hz bandpass at the moment with 1500Hz audio standard, and occasionally suffer from QRM a few hundred Hz away from the 200Hz wide WSPR segment.

I see under Setup, Advanced, a RX BFO setting that defaults to 1500Hz. I suspect I could change that to 1000Hz and center my TX and RX audio on 1000Hz and narrow my RX BW to 240Hz, changing my QRG up 500Hz.

Before I fiddle around and re-invent the wheel, has anyone done this? I'll have to re-read the dox for the prog - haven't done so for a year and it might be covered. It's a weekend job for me. Too busy during the week. I might even look at the narrow hardware CW filters for the 857 and 897 but the DSP does a good job and I'm aware of some ringing issues with the available aftermarket very narrow filters that are available for these Yaesus.