Looking to notch out a 400HZ whine from some audio circuits connecting remote manned sites to a central location. The audio is microwaved from remote location to the central location. Would like to know the formula for determing the resistor and capacitor values. The overall bandpass is 300HZ to 3KHZ. Or would it be better to just use an High Pass filter. Problem with that is getting the inductors locally. Up here In Fairbanks our choices are very limited.
Thanks.