[RFI] RFI to netgear router

Tom Cox tomcox at iquest.net
Sun Aug 7 16:33:41 PDT 2011


I came into this conversation late, so I apologize 
if I am missing something. I assume the coffee can 
is a core for some turns of coax intended as a 
balun. I can see that working for some upper HF 
frequencies, or even 6M, but I don't think it 
would choke off much common mode current at 2M.

Since the system worked before, the interference 
with the router probably isn't caused by common 
mode current, but you still need to check the 
antenna system, which may mean borrowing an SWR 
meter or, better yet, an MFJ antenna analyzer. 
Maybe you can borrow the analyzer's owner as well, 
to operate it.

Putting the right mix ferrites on the router leads 
is always a good idea, since this class of devices 
is known for radiating RF, as well as being 
susceptible to it. It can't hurt, in other words.

Can you inspect the cable and antenna for damage? 
Also, check that the ground wire is intact and 
that the connections at all points are not 
corroded. Doide action from a corroded connection 
in the feed line or ground will cause RF problems, 
as well. Of course, corrosion on the ground 
connections will impair the lightning protection, 
too, which could make hitting repeaters a pretty 
moot point.  :)

Good Luck,
Tom, KT9OM

On 8/6/2011 2:00 PM, rfi-request at contesting.com 
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>     1. Re: RFI to netgear router (Brian Reid)
> ----------------------------------------------------------------------
> Message: 1
> Date: Sat, 6 Aug 2011 02:24:44 -0400
> From: Brian Reid<kb3wca at gmail.com>
> Subject: Re: [RFI] RFI to netgear router
> To: rfi at contesting.com
> Message-ID:
> 	<CAKzK+24HEEp7SwYeXZiskpcy2x55iGpK2k8nCD4c0Tcc00_nzA at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
> Thanks to everyone for the responses. I'll try to answer the questions asked
> of me and suggestions made all in one.. As far as the location of the router
> versus the antenna/feedline.... I live in a 2 story brick rowhome. The shack
> is in the basement, with feedline running a short distance to the outside,
> and then to the roof. There is a choke balun in place from when we installed
> the antenna, and it was made using a folgers coffee can. There is ground
> wire running from the antenna down to a copper ground rod in the back yard.
> This ground rod in turn has a piece of copper wire that runs off of it to
> the radio's mounting bracket, wrapped around one of the mounting screws. I
> do not own a swr meter, but when the antenna was installed, we used one, and
> the highest swr was 1:2 at 144... flat the rest of the band.  I typically do
> not require high power except when I am trying to hit repeaters 70-80 miles
> away or more when conditions are good. I am thinking of trying the ferrite
> chokes on the wires on the router. I normally use the radio after dark when
> everyone else in the house is asleep, so the internet getting interrupted is
> not really a big deal. Still a pain in the ass nevertheless.

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