[RFI] Zoom X6 DSL Modem loses internet connection

W0MU Mike Fatchett w0mu at w0mu.com
Wed Feb 25 11:47:06 EST 2009

I tried the Excelsious filter and it does not touch my 40m issue.  Their
specs say 10mhz and up.  I was hoping they were off a bit.  The filter
appears to be well made.  I never noticed problems at those frequencies so
it is hard to know if it is doing anything.  

I have ordered the parts to build the OK filter.  I will post my findings.
Those parts should be in today or tomorrow.

"A slip of the foot you may soon recover, but a slip of the tongue you may
never get over." Ben Franklin
-----Original Message-----
From: rfi-bounces at contesting.com [mailto:rfi-bounces at contesting.com] On
Behalf Of Jim Brown
Sent: Friday, February 13, 2009 10:38 AM
To: RFI List
Subject: Re: [RFI] Zoom X6 DSL Modem loses internet connection

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 modem.

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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