I have an s8 pulsating noise on 75 meters exactly every 53 Khz. It is strongest on 3754 and occurs every 53 Khz up and down the band. It is weak by the time you get down to 3595 and by the time you get up to 3966. Anyone ever hear this type of RFI that is every 53 KHZ. any ideas. ??? thanks Van W4GIW