I believe it's a digital servo and they do make a slight humm. If, as suggested above, it's not your end point settings, then it's just a normal sound that digitals make. As far as you antenna is concerned, you should never cut a FM or AM receiver wire. It will cause you to have glitches. The wire is supposed to be a certain length set my the manufacture. I have two XXL rx's that I will sell you for a good deal, if you're interested, PM me. Hope this helps.
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