I recently received a CW filter Kenwood YF-88HCW for my TS-520. I believe it is 200 Hz and 8.8307 KHz IF. I don't know what other rigs it will work in but I no longer have the TS520. So if it will be useful for someone I will ship for 50ドル.00 postpaid USA. Healthfully yours, Don W4BWS .