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Re: [RFI] Linksys Router Birdies

To: "'Roger \(K8RI\)'" <k8ri@rogerhalstead.com>, "'Charlie Gallo'" <Charlie@TheGallos.com>
Subject: Re: [RFI] Linksys Router Birdies
From: "Wes Attaway \(N5WA\)" <wesattaway@bellsouth.net>
Date: Thu, 11 Mar 2010 21:17:27 -0600
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
My experience is similar to Roger's. I have several computers, all
different, with a wireless Access Point, a Cisco router, Bellsouth DSL
router/modem (running in bridge mode), network switch, KVM switch, and other
stuff all within 3 to 5 feet of the radio and have never noticed any noise
or birdies. Antennas are 100'-150' away, which might explain it.

One thing I have found from past experience is that if any coax plugs are
not properly installed (poorly soldered shields, etc), and are not screwed
on tight, then various potential noise sources can become a problem.  This
is the first thing I would check if I had a noise problem because imperfect
shields in the shack would allow vastly increased noise ingress.  

I think the best way to attack network noise problems (assuming no connector
problems) would be with multiple turns of CAT5 through suitable cores. This
seems to be what most people are finding success with, particularly in
situations where the antenna may be close enough to pick up some direct
radiation from the network equipment.

Shielded CAT5 is really not required and, as has been pointed out, is not a
workable solution for the equipment situations we are dealing with.

------------------ Wes Attaway (N5WA) ------------------
1138 Waters Edge Circle - Shreveport, LA 71106
    318-797-4972 (office) - 318-393-3289 (cell)
        Computer Consulting and Forensics
-------------- EnCase Certified Examiner ---------------
-----Original Message-----
From: rfi-bounces@contesting.com [mailto:rfi-bounces@contesting.com] On
Behalf Of Roger (K8RI)
Sent: Thursday, March 11, 2010 8:50 PM
To: Charlie Gallo
Cc: RFI@contesting.com
Subject: Re: [RFI] Linksys Router Birdies

Charlie Gallo wrote:
> On 3/11/2010 Tony wrote:
>> All,
>> What is the best method of getting rid of router birdies? ...snip...
>> Tony -K2MO
> I did something SLIGHTLY different than most - I used a Type32 ferrite,
but I used a fairly small one - 1/2" inner, about 3/4" long, which will NOT
fit the RJ-45 plug through it, so I cut them off, put 3-4 wraps (as many as
would fit), and put a new end on (I usually make my own cables, so this was
no big deal).  
To save some work they make snap one, or clamp on ferrites  an inch or 
inch and a half long. They come large enough you might be able to get 
three turns though one. The ones I have are about an inch long and will 
only take two turns.
> One interesting thing I found - MOST of the RFI was NOT coming from the
router end of the cable, but from the PC end!  MUCH greater reduction in
signal if I put the ferrite on the PC end.  Of course, I ended up doing BOTH
ends.  My birdies went from S9 to about S1, which is my background level on
a GOOD  day (on a BAD day, I have S7 background from DC to daylight here)
(my antenna is a DX-EE 20ft or so straight up over my shack)
I've been very lucky, with the router, modem, and switch, only about 3' 
from the one station, but about 30' from the 160 and 75 antennas. A 
number of the coax runs and CAT6 run together for close to 30'. On the 
other end of the CAT6 runs are two quad core computers with the core 
speed at 3  and 3.2 Gig. They are all running on a Gigabit network.  Now 
I'm getting ready to update routers which with the reports I hear always 
makes me nervous. Some of the new routers are pretty fussy and I run 3 
different operating systems, on 5 computers with a total of 3 different 
motherboards and 5 different video cards (most top end).  So far I've 
not needed any of the ferrites on network or power cables. I hope that 
doesn't change with the new router. The old one has led a hard life and 
is not much more than a circuit board with connectors along the edge.


Roger (K8RI)
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