Well, the modem does operate at radio frequencies so you can maybe hear interference from the modem?
Try it with the modem powered off?
I'm not using the external modem I'm using the HH5 by itself as you can't disable the internal modem unless you connect it up to an external modem. I got it on a high table and when I literally point this cheap-o radio at the master socket below it it emits loud static. It's literally not near the HH5.
I hope that's more understandable as I'm terrible at explaining things.
I tried it turned off and still got loud static so what does that tell you? Something bad I assume.