ARRIS Cable Modem causing RF Interference inmy shack

[ND4Z]

I am a customer of Time Warner Cable for my TV, Internet, and telephone.
They have provided me with a ARRIS model TM602 modem for the internet and telephone service. I started to get all sorts of Hash noise very strong all over the bands on my HF rig. At first I had no clue where all the noise was coming from.
I hooked up a battery operated FT 817 qrp rig to my antenna and killed the main breaker for my whole house. The noise went away, and as soon as I brought the power back up the noise came back. I than took hours of troubleshooting each circuit and found it to be coming from my ARRIS Model TM602 cable modem. I called time warner and a technician came out and replaced the ARRIS modem the same as the bad one. To our surprize the new ARRIS TM 602 was putting out the same nasty sounding pulse noise. We than tried a replacement modem made by Sceintific Atlanta which immediataly fixed the problem. So I am assuming that the ARRIS TM602 was not engineered to keep noise emmissions from radiating to ham radio equipment. Wonder if anyone else has had a simular problem with the ARRIS TM602 modem? It can sure cause a big problem for ham radio ops.:confused:
73,
Rick ND4Z

[K7CJ]

Rick, a lot of these modems have really bad switching power supplies which can send RFI thru the AC mains. If the modem is in the same room as your radio gear, then you may have RFI ingress and/or the AC wiring is acting like an antenna and radiating the RFI.

To solve the AC adapter issue, I use cheap AC power strips and then add a brute-force AC filter from CORCOM. This helps keep the noise isolated and prevents it from getting into the house wiring. (The CORCOM filters can be purchased used or new for $5-30 depending on how much amperage you want to support.) I use about four of these custom strips around the house and two in the radio room. If you have a lot of AC adapters, lamps, fans, etc. then it's a good, cheap solution.

Since you resolved the problem with a new modem, I'm guessing a noisy power adapter was the culprit.