I bought a used EX1R recently, and I'm having a weird problem with it. If I plug either of my two wireless mic systems into the XLR input (either one), I get a high pitched whisle-type noise long with the sound I am recording (which I hear in the headphones as well). If I plug the same wireless mic receivers into a Mackie mixer, and then plug the mixer into the EX1R, there is no noise. This is true whether I set the mixer to line or mic level output. Also, if I plug a wired microphone into the EX1R, there is no noise. And if I plug the wireless mics into my Sony NX5U, there is no noise. This problem has me baffled and I'm hoping someone has a solution as it's not always possible to bring the Mackie mixer to my shoots (if there's no A/C power, for example).
When feeding the EX1R have you tried adjusting the gain out of the wireless mic receiver or the mic input gain on the EX1R? If you look at the recorded sound in an audio program can you see if it's a particular frequency?
It's quite possible that your preamp setting is amplifying some harmonic of a carrier frequency that would normally be masked. Without seeing a sound analysis it's hard to know.
This really sounds like a cabling issue or even an RF jam from a nearby digital signal. I would validate the unit works with other devices. Also, are you powering using internal batteries? That's good because sometime the issue is power.
After validation, make sure you are line to line or mic to mic and also make sure your actual mic/cable is not boning you. Basically you really need to validate that your unit and accessories are in good working order. I have an EX3 and hitch hike my Lectos all the time with no problems but that "whining" sounds familiar. Do the validation and then attack the camera.
If you have are sure your unit is working well with other units, then consider you may have an open ground mic cable ground and try swapping cables.