Rode NTG-2 hum noise into HMC70. How to fix?

My computer and Mic (SM58) have hum issues. But if I hook my mic into my camcorder direct out doors, there is no hum. I sometimes use My mixer, which is mic(s) to mixer to camcorder, a low hum is produced if I turn on phantom power. XLR cables are good for getting rid of cross interference for instrument and mics. TVs, computers and the like, they are not that good at eliminating noise.