Around 1400 hertz I get a whine

I keep having a problem in my audio that around 1400 hertz a whine develops. I believe this is only happening on my wireless unit. The units are the Shure ULX series. It doesn't matter if it is a hand held or clip on mic. I run the audio through a Maxie mixer before it goes into the camera. I do not hear the tone when recording but it is there once I import the clips. Once the audio is compressed and limited the whine is much louder as would be expected from these processes. What is the best way to get rid of this sound in FCPX or at least minimize it?

I solved this with a parametric EQ that I made into a very narrow notch at 1480 hertz. It is not all gone but is a lot less annoying.