Twiggs Cty
The loud buzzing sound maybe Jones Cty, they have a NXDN NEXEDGE System that the 396xt can not decode. First try a weather frequency or a local fm broadcast station. If they are clear, its not electrical interference. Second I have sent a file for twiggs cty, that has Macon Ga, a trunked system you should be able to pick up. Counties around Twiggs are also there. Jones Cty has the system assigned to quick key 5. You can deselect by punching the 5 button once or twice. Two times its lockled out copmpletely. Once locked out until you power up again.Like I said before, the buzzing sound is what a NXDN sounds like. If the sound is exactly like what you have been hearing, might be receiver overload because the Jones Cty frequencies and Twiggs are not real close. Possibly, if over load, turn attenuation
To toggle the attenuation for a conventional channel on or off Hold on the channel and press Func then 7(att). Press Hold to resume.
To toggle the attenuation for a trunking site on or off Hold on the site and press Func then 7(att). Press Hold to resume.
To toggle the attenuation for a search on or off (Search with Scan) press Func then 7(att) while searching. (or hold first).
To toggle global attenuation Hold on any channel and press Func then press and hold 7(att).
Just stabbing in the dark but this might be the answer.