[amsat-bb] Re: "Birdies" from Linksys Wireless router

[Jeff Yanko]

I found this topic interesting since I too have a Linksys WRT54G router, 
which is also in the shack.  I decided to listen for the "birdies".  I tuned 
to 145.93 mHz on the HT while sitting in the chair and.....nothing.  Hmmm. 
So I stood up and moved around then lo and behold a strong birdie  as I got 
very near the router.  I did notice one thing, the birdie completely 
disappears about 2 to 2.5 feet from the unit.  My router is on one side of 
the room about 12 to 13 feet away from the desk.  I have absolutely no copy 
of the birdie with the HT on the desk.  A possible solution could be if you 
have a large enough room, move the router off of and away from the desk with 
the VHF equipment on.

73,

Jeff  WB3JFS


----- Original Message ----- 
From: "Nate Duehr" <nate at natetech.com>
To: "Amsat-Bb" <amsat-bb at amsat.org>
Sent: Thursday, May 08, 2008 11:58 PM
Subject: [amsat-bb] Re: "Birdies" from Linksys Wireless router


>
> On May 6, 2008, at 4:58 PM, Mark L. Hammond wrote:
>
>> Hello all,
>>
>> The launch of Delfi-C3 has brought to my attention a very strong
>> birdie at 145.930 MHz that clearly comes from the Linksys WRT54G
>> Wireless router that sits in the shack.  Forcing the wireless signal
>> to another frequency/channel has no impact whatsoever...
>>
>> Anybody on the list have a clever solution (other than 'get a
>> different router' or 'move it' or 'shut it off', etc...hi hi) that
>> they may have used for a similar problem?
>>
>> Thanks,
>>
>> Mark L. Hammond  [N8MH]
>
>
> Mark,
>
> My Linksys WRT54GS annoyed the heck out of me with birdies, so I
> replaced it with a cheap Netgear.  Not a peep out of it, since then.
>
> I liked having DD-WRT on the Linksys device a couple of years ago when
> I was using it, but the Linksys is stashed away in a box for
> "emergencies" and otherwise banned from my shack now, due to the RF
> issues.
>
> Ironically I had already tried the "power the house down to see if the
> interference is local" and had decided it wasn't, and that I needed to
> do some DF'ing... then I realized that the server and the WRT54GS were
> on the UPS, which I had NOT shut off.  (Doh!  Smacks forehead...)
>
> I did try briefly to do things like ferrites on the "goes-intas" and
> "goes-outtas", etc... to no perfect effect.  I could mitigate some of
> the noise, but the thing was ultimately just too noisy.   The wall-
> wort for my particular model (there are something like six different
> hardware models of the WRT54GS -- another annoying pattern of the
> small router manufacturers) was just a transformer... whether or not
> there was a noisy switch-mode power supply inside the Linksys, I
> didn't investigate.
>
> Someone else commented about using "quality Cat 5 and Cat 6 cable"...
> since Cat 5 and Cat 6 are ratings for UNSHIELDED twisted-pair (UTP), I
> have no idea what differing "quality" levels of cable would
> accomplish.  Ethernet via Cat 5 is SUPPOSED to leak signal.  Someone
> missed reading the standards, I guess.  The comment made no sense to
> me from an RF engineering perspective.
>
> One possible "fix" for that type of noise could be to run Ethernet on
> SHIELDED twisted-pair (STP) cable, and ground the "drain" wire at ONE
> end (don't ground both ends, you WILL create a ground loop, and it
> WILL drive you crazy... eventually) but it no longer will meet the
> Ethernet specifications for cross-talk, etc.   Frankly, it works --
> but don't go doing it in the office or someplace where the network is
> critical.   They make special RJ45 connectors with metal strips
> "wrapped around" the connector body that can be crimped in such a way
> as to capture the drain wire, and that are built to ground to special
> female RJ45 sockets... again, only do this on one end... and they were
> usually used for things like telco T1 carriers that *are* specified to
> use STP cabling in many instances.
>
> I don't think the real noisemaker in the Linksys was the Ethernet
> signal itself anyway -- it certainly leaked out of the cheap plastic
> (virtually unshielded) case via the Ethernet cablilng, but the
> Ethernet noise wasn't the problem.  It was so cheap to try another
> router, the "fixes" weren't worth my time.  Easier to buy from Netgear
> who's had a pretty good track record of actually building properly
> shielded products, back to when their little switches, hubs, and other
> devices were all in the "blue metal case", complete with a real ground
> terminal and lug on the back-side, which is a "body style" they're not
> making many of anymore...
>
> Same thing with cheap plastic PC cases... noise galore leaking from
> those, too.  Makes one miss the days of steel cases and PCs you could
> barely lift.
>
> My IBM/Lenovo T43 provided by work throws all sorts of VHF crud,
> enough to completely obliterate the front-end of my poor Kenwood TH-
> F6A "broad as a barn door" receiver on most of the VHF band (IF mixing
> perhaps), and the MacBook is more bearable, but the LCD backlight
> system makes RF noise.
>
> I guess with the ever-lowing price of fiber-optic based networking
> gear... that's the ultimate in quiet, as long as you can keep the
> routers/switches themselves from leaking crud... but that's definitely
> overkill.  Overkill is sometimes what we hams do best, however.  I
> have seen the photos to prove it.  (GRIN)  We are the only HOBBY
> organization that regularly launches satellites... or so I'd like to
> believe.  (BIGGER GRIN)
>
> Good luck killing off the Linksys RF interference gremlins.  Netgear
> highly recommended!
>
> --
> Nate Duehr, WY0X
> nate at natetech.com
>
>
>
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