Do some experiments to better characterize the nature of the problem. Move the mic around. Does it have more in different locations? Does it occur when you're talking or also when it's silent (be sure you disable all noise gating etc.) Is the static correlated with talking or independent, the same regardless of volume of voice? Posting a recording might help people here track it down (wav file). If it's purely analog, do you have another device you can plug it into? Can you run the device off batteries? If a PC, an external USB capture box might help.