Cable modem RFI

[KG6AOV]

I have a Motorola SB6141 cable modem about 5 feet away from my Yaesu FT-450AT. Unfortunately, it seems to be contributing to about 2 S-units of noise on at least some of 40 meters when powered. I replaced the wall wart with a direct connection to the shack's 12V supply with no change, as well as placed snap-on ferrites on almost all of the wires coming out of it except for the coax feed. I'd put a choke on the coax feed too, but the modem's status page said that it was using 28MHz for uplink, so it's probably not a good idea.

Is there anything else I can do besides going without Internet while on the air? (My setup is already pretty marginal as is due to being HOA restricted in a condo, so I'd like to try to improve my S/N ratio as much as possible.) Also, would something like the ANC-4 help?

Thanks!

[WA7BBI]

Go ahead and try the choke on the cable. Snap on ferrites should only affect Common Mode radiation and not the Differential Mode (ie. the 28 MHz signal). You have nothing to lose. Good luck.

Jim, WA7BBI

[WB4SPT]

This is not a wireless, right?  If the coax choke doesn't do it for you, make an aluminum foil case for it, wrapping a couple of turns around and crimp close to the wiring.  If it's direct chassis radiation, at least you will find out.  If it needs to stay, then decorate it.

[N4NYY]

I have a Motorola SB6141 cable modem about 5 feet away from my Yaesu FT-450AT. Unfortunately, it seems to be contributing to about 2 S-units of noise on at least some of 40 meters when powered. I replaced the wall wart with a direct connection to the shack's 12V supply with no change, as well as placed snap-on ferrites on almost all of the wires coming out of it except for the coax feed. I'd put a choke on the coax feed too, but the modem's status page said that it was using 28MHz for uplink, so it's probably not a good idea.

Is there anything else I can do besides going without Internet while on the air? (My setup is already pretty marginal as is due to being HOA restricted in a condo, so I'd like to try to improve my S/N ratio as much as possible.) Also, would something like the ANC-4 help?

Thanks!

I had a friend that had a similar problem and he shielded it using a metal case and grounding it. The problem is that I cannot recall if it solved it. It was a while ago. I suppose it would be cheap enough to give it a shot.