Audio buzz on 436HP when connected to USB

I have been trying to stream my 436HP for some time, but whenever a USB connection is established to the scanner, I get an AUDIO BUZZ on the line in of my streaming computer. I have tried various desktop and laptop computers, even tried USB powering the scanner from a secondary battery powered computer, no dice. The only thing that would work was a serial port connection, which provided clean audio. The problem is, I need to remote monitor this scanner, and the batteries don;t last long enough with USB plugged in.

I am out of ideas now. I even bought a USB audio card to see if that would circumvent the issue, no dice. When UBS port connects to the USB or GPS jack, the buzz begins instantly on the receiving PC. I would really like to resolve this. I a using the stock Uniden USB charging/data cable with that magnet thing on it.

Paul

Are you using the USB cable that came with the scanner, which has an RFI choke?

Yes, using the stock cable that came with it. I am going to try a wall jack USB plug, but I doubt that will make a difference since my second PC was still passing noise through the scanner through the unrelated USB jack.

Paul

What antenna are you using? Is it grounded, and if so, how?

Various top of radio antennas, but it does it with ungrounded magnet and clamp mount NMO's as well.

Paul