Topband: Need More Help Getting rid of Router Birdies

Ed Gray W0SD w0sd at
Thu Feb 21 09:40:32 EST 2008

First of all thanks for the help!  I have some new ideas on things to 
try.  I is very much appreciated.

I will supply some additional information in regards to these questions 
ahead of each paragraph/paragraphs.

Brendan Minish wrote:
> Here are some thoughts on the Ethernet Birdies 

I am using cat5e cable, not shielded/screened.  I have the pairs correct 
using 568A and use EZ-RJ45 connectors and the expensive Platinum tool 
for crimping.  The Cat5e cable runs from the router to the computer  are 
direct, no wall outlets and punch downs.  Every run is an end to end run.
> 1/ are all your cat 5 runs properly wired and terminated with proper 4
> pair Cat5 (or cat5e) cable? 
> The bridies you hear are the ethernet carriers, the cat 5 is 4x 110 Ohm
> balanced lines, if the crimps are bad or the pairs are incorrect then it
> radiates like heck 
> 	Generally we use 568B here in europe but 568A is equally acceptable 
> 2/ Are these screened or unscreened runs? If screened are the proper
> grounding metal body RJ45's fitted ? 
> Unscreened runs should be ok too, if done right with good quality,
> undamaged cable.
> Are you using punch downs or are all runs 'end to end' (end to end is
> better from an EMC perspective)  
> If punchdowns what type, how neat, what else is there? for example in
> house are some of the cat5 runs used for phones too ? 

I need to do some investigating here as the problem seems to come from 
the computer network card area but I am not sure what you mean on 
grounding as it is a plastic plug but of course there is the ground wire 
in the twisted pairs.
> 3/ are the Ethernet cards in the PC's grounding the RJ 45 socket body
> correctly at the backplane of the PC, some do and others just have the
> socket floating which is bad from an EMC perspective, no matter how well
> the case is screened this creates a 'pin 1 problem '  

I don't think it is on this end based on the sniffer approach. The 
router is in a plastic case.  I forgot to mention with the DSL modem 
turned off but the router on the birdies are the same as with the DSL 
modem on.
> 4/ the router end is more likely to be the issue, try an ethenet hub, a
> decent(ish) one in a metal housing. does the nose go away / reduce
> significantly?
> Power up your DSL router, any changes? 
> now connect your ethernet hub to your DSL router with a short patch
> lead, does the problem come back ? If so choke all wires leaving the DSL
> router, including the phone and power cords. don't put it's plastic case
> on top of or close to anything that can act ans an antenna for it 
The noise seems to be coming from the Computer network card area in the 
computer but it only occurs when the CAT5E cable is connected to it with 
the router operating.
> 5/ still got issues? use a nearfield loop (single 2" closed loop on the
> end of some coax) with something like an FT817 to see what the noise is
> using as an antenna

I am between a rock and hard spot as I just built and have moved into a 
fantastic new radio room and ran all the cat5E cable from the router 
through the basement, up the inside of the wall, across the ceiling and 
down the wall and under a false floor to the operating bench.  Again 
this is an end to end run with an EZ-RJ45 connector on each end.  That 
is where you can put all the twisted pairs through the connector and the 
wires all stick out the end.  The expensive crimper cuts them off and 
rachet crimps them.  Supposedly the advantage is you have each wire 
almost exactly the same length and the twisted part of each pair comes 
as close as possible to where it is crimped.  I don't think you can do 
any better than what we did.

 From a practical stand point these runs can not be replaced with out 
doing an extreme amount of destruction to the new construction.

As I write this I have come up with an idea.  I could move the DSL modem 
into the new radio room along with the router.  I could then have very 
short runs of CAT5E cable and if still a problem I could even tried 
shielded CAT5E cable.

> 6/ consider rearranging your network topology to have shorter runs of
> Cat5 to a central hub (or switch) and replace the long run with fibre, I
> have seen 100Mb Media converters (ethernet to multimode fibre) for as
> little as 30 euro each on ebay. A single terminated run of multimode
> fibre will not cost too much these days in a custom length and will be a
> bargain in a 'generic' length   
> All of the Ethernet problems I have seen to date are resolvable,
> domestic DSL routers are often the worst offenders because they don't
> take care to ensure very accurate line balance on the cat5 pairs,
> grounding is ineffective from an RF perspective, the phone line is often
> involved and the power supply provides effectively no RF isolation from
> the mains, all of these issues can be addressed 

Mean while I am going to get a wireless card or USB wireless connection 
and based on my wireless laptop should get rid of the problem while I 
work with the above ideas and see if I can resolve it.  I will have to 
do some testing and see if the wireless slows my upload and download 
speed much.  If the speed is close given the effort I have put in 
already with no solution it may be the be the best way to resolve the 
solution.  Several of you e-mails saying this is how you solved your 

For possbile help to others in the future I will report other results.

> 73
> Brendan EI6IZ 
> (IRTS EMC guy)   

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