[RFI] Zoom X6 DSL Modem loses internet connection

Jim Brown jim at audiosystemsgroup.com
Fri Feb 13 12:38:29 EST 2009

On Fri, 13 Feb 2009 10:04:32 -0700, W0MU Mike Fatchett wrote:

>Any suggestions on where to start would be appreciated.  It only seems to
>happen on 40m.

You should also call your DSL vendor and tell them that their modem has RFI 
problems, and ask THEM to fix it. It IS their problem, not yours. W8JI had 
issues with his modem, and got a replacement that worked. 

Study  http://audiosystemsgroup.com/RFI-Ham.pdf  

If you want to fix it yourself: 

1) Start with a choke tuned to 40M on each cable connected to the DSL 

2) If that doesn't fix it, leave those chokes in place and add a choke at 
the Ethernet switch or hub. 

3) I've recently learned of a company in SoCal called Excelsus that sells 
filters that they say will eliminate RFI to DSL modems. Google to find 
them. I'm currently writing the EMC chapter for the ARRL Handbook, and 
called them a week ago for a sample unit so that I could mention them in 
the Hanbook. So far, no response. There's a more established company in 
Ohio called KCOM who makes telephone filters that are well known to work 
very well on telephone lines. It might be worth a phone call to ask if they 
have a DSL filter. 


Jim Brown K9YC

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