Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: Prev 1 [2]   Go Down
  Print  
Author Topic: RFI from Linksys non-wireless router?  (Read 3705 times)
KC2MMI
Member

Posts: 620




Ignore
« Reply #15 on: May 21, 2004, 07:08:36 PM »

Mike-
 A good thought. But the wall wart in this case is not emitting RFI, there is no noise from the wall wart. Once you plug it into the router, the router beings emitting gobs of RFI/TVI. Unplug it--without turning off power to the wall wart--and the problem goes away.

 The problem is in the routers. At least, I've neer heard of a computer being built in a plastic case, with no shielding over the MB and CPU, that could meet ClassB certification. Except maybe my Palm, but Palm's were built by better "parents" than most computers.<G>
Logged
AA1VX
Member

Posts: 6




Ignore
« Reply #16 on: June 06, 2004, 01:45:37 PM »

I finally got around to putting the router into a cookie tin with just the RJ-45 cables sticking out, but the interference was still there.

I guess the next step is to buy a router from a different manufacturer.

Any suggestions on which one(s) won't cause QRM on the ham bands?

Thanks again, all.

73,

Dave AA1VX
Logged
K7NA
Member

Posts: 6




Ignore
« Reply #17 on: June 06, 2004, 06:57:15 PM »

     I also am experiencing interference in the form of numerous phantom carriers up and down the 6-meter band which trace back to my plastic encased D-Link Dl-604 router. I've tried ferrites on the router power cable both near the wallwart and near the router itself to no avail. I can unplug the Cat5 cables leading to the SB5100 cable modem and to each computer with no effect on the 6-meter interference. The only thing that solves the problem is to unplug the power cable and thus power down the router.  
    As I indicated, my noise appears as numerous carriers across the 50 mHz band. I do hear a "frying noise" at some spots on the dial on 6-meters as well as HF and I suspect it is coming from somewhere in my neighborhood, not from my house and not from my router because it does not disappear when I remove power from my router.  Interestingly, another source of interference I located in my house was my wife's fax machine! Just plugged in, the machine created a noise approximating that from flourescent lights on HF.
     Yesterday, I purchased (temporarily) another router (Netgear RP614 encased in plastic) and installed it in place of the D-Link unit. Other than a slight shift in the frequency of the phantom carriers that appear up and down the 6-meter band at various signal strengths, no improvement was noted at all. I immediately returned the Netgear unit to the store. Next, I plan to purchase a metal encased router to  ascertain whether that affects the level of noise.  Like many, I am not in a position to change the location of my computer, router or ham antenna. On 6-meters, I use both a Diamond DP-GH62 vertical and a Par Omniangle loop and both pick up the router interference.
     If someone finds a real cure for this interference, by all means, please share it with us!

Vince  
Logged
AB0KB
Member

Posts: 4




Ignore
« Reply #18 on: June 12, 2004, 03:20:10 PM »

Add us to the list.  We recently installed a Linksys non-wireless router and it completely took out our "home" 2m frequency.  We have been running a netgear for a while (family of four, all hams and techies, we actually intend to run both routers...) and have not noticed any interference from it.  It sounds to me like the FCC cert was bogus.  Maybe Hollingworth would be interested in this case?  We have all our routers, most of our hubs (except the wireless one a couple in other rooms) and broadband modem co-located in a little "nook".  Given the experiences of others, I think the easiest approach for me (that has good odds for lots of significant improvements) is to build a mini-screenroom mounting enclosure and put all our network stuff in it.  I'm interested in what others are doing and (should I get to this project in a reasonable amount of time) I'll let you know how it goes here.
Steve, AB0KB.
Logged
AB0KB
Member

Posts: 4




Ignore
« Reply #19 on: June 12, 2004, 05:51:36 PM »

Here's a quick, and discouraging, update.  Before going to the effort to build the cabinet, I did the "rapid proof-of-concept" test.  I have a lot of surplus copper tape, so I took the router apart and carefully copper-taped the entire inside of the case (repunching the air and LED holes).  It's clear the pcb designer was assuming a conductive case as the one mounting screw through-hole on the pcb (to screw into the case) has routed to it the ground plane and the drain wire for the shields around the network connections.  I made sure my copper shield made the connection with the pcbs single point shield ground.  Although there was improvement (I can at least squelch it on the 2m in my lab) but is still stinks.  I can't squelch it on the family room's 2m (in the same room as the router).  By the way, if you google "linksys router RFI" you get a ton of hits.  One of the threads I was reading mentioned an existant class action suit against linksys.  Don't know if that real or not as googling "linksys RFI class-action lawsuit" didn't hit anything real.

Steve
AB0KB
Logged
AB0KB
Member

Posts: 4




Ignore
« Reply #20 on: June 12, 2004, 09:29:24 PM »

This time my quick update is an encouraging one.  I dug 5 surplus torroids out of my "passives" drawer (Fair-rite #65 material 1.142" O.D., 0.746" I.D., 0.545" Length, not in the catalog so it may not be available off-the-shelf) and put one on each network cable connecting to the router (3T each). This plus the shielding I added earlier, did the trick.  The router RFI is no longer audible on any of my 2m rigs.

Clearly this router (Linksys BEFSR41) is AWFUL on BOTH conducted and radiated emission. But if your junk box is as deep as mine it's a pretty easy fix.

Steve.
AB0KB
Logged
KD4OUZ
Member

Posts: 4




Ignore
« Reply #21 on: June 13, 2004, 09:19:25 AM »

I have no way of getting any ferrite beads. Guess I should do a little surfing on the internet. If thats the case of correcting this, I would have to have beads on the power cord, and all of the CAT5 I have.....4 from the linksys router and four from a 8 port hub which also seems to transmit the linklsys routers RFI, cause one of the cables has to be pluged into the linksys (main hub)to get the internet signal to the 8 port hub.

This is starting to sound like a pain, and possibly costly...and I would imagin no gurantee of the results.

Its a shame...as soon as you walk into my house your 2mtr. reception is totally whiped out, cause of all the cat5 in this house  Sad
Logged
AB0KB
Member

Posts: 4




Ignore
« Reply #22 on: June 13, 2004, 06:02:59 PM »

I don't agree with the details in your message but we may be in agreement on the big picture...

I only put toroids on the five network cables going directly into the linksys router.  And I did it right at the router.  I did not put any beads on other cables and our "home" network includes a wireless hub, two sixteen port hubs, an eight port hub and a Netgear router (in addition to our Linksys).  We have cat5 cable running all over the place.  I did not put any toroids on any power cables either.  At our house, only the linksys was an RFI piece of crap.  Everything else appeared to be built according to law (Admittedly my words are harsh here but having put electronic equipment though RFI testing myself, I seriously doubt the linksys router, in the configuration we purchased it, was ever legitimately tested as required by law)

However, your conclusion that, since you don't have the right junk on hand (as I did) that it may not be worth going and buying it, is probably correct.  On another Forum (I forget which one) which I found when reading up about linksys RFI yesterday some advice was given that I believe to be very sound (even though I didn't really follow it).  The advice was don't try to fix your cables, they are not the problem.  If you have a linksys router, hit is with a sledge hammer and your RFI problems will go away.  Then spend the same amount of money for a correctly manufactured router that you would have spent on "fixing" your cables etc. and get better results.

If you do decide the go the challenging route, you will need to completly enclose the router in shielding in addition to putting Ferrite on the network cables you plug into the Linksys.  Neither shielding, nor Ferrite will fix it on their own.  You need both.  

I happened to have surplus copper tape and ferrite toroids on hand (plus I love the challenge of figuring out and fixing other people's electronic screwups, it's a great way to reduce the frequency of my own).  Otherwise I doubt I would have handled it the way I did.

Good luck and best wishes,
Steve
AB0KB
Logged
K7NA
Member

Posts: 6




Ignore
« Reply #23 on: June 22, 2004, 01:09:43 AM »

I've tried two plastic-encased routers for my wired high speed internet service and both (a Netgear and a D-link) were horrible for creating carriers across the 6-meter band. I purchased a refurbished metal-encased Netgear RP-114 for $14.95 on Ebay last week and after placing it into service found a significant improvement in the noise situation. The carriers across the band are now down around S1-2 or weaker. I plan to wrap each Cat5 cable in a toroid and hopefully, that will reduce it even further. It appears a properly installed, metal-encased router is quieter than the popular plastic boxed units out there on the shelves of Best Buy, Office Depot, etc.  

Vince
Logged
AA1VX
Member

Posts: 6




Ignore
« Reply #24 on: June 22, 2004, 09:53:24 PM »

I ordered a refurbished RP-114 Router today. It has a metal case and hopefully will not act as a noise transmitter throughout the HF bands. I'll post the results to this forum after I receive it and put it in place.

Thanks for all the suggestions thus far.

73,

Dave AA1VX
Logged
XYZZY
Member

Posts: 2




Ignore
« Reply #25 on: June 29, 2004, 08:13:34 AM »

I hope I'm not intruding. I am not a ham radio operator. Just wanted you to know that I'm experiencing similar problems with my SMC Barricade 7004ABR non-wireless router. The RFI I get is on the AM band on every radio in my home. When I power off the router, all my AM radios work fine. More RFI above 1MHz than below. I read that sometimes a ferrite core on the router power cord will reduce the RFI. Where can I get more info on this solution? Can I build my own? Or do I need to purchase it? Anyway, I'm in contact with SMC support and will post here any useful info they provide.

John
Logged
KC2MMI
Member

Posts: 620




Ignore
« Reply #26 on: June 29, 2004, 09:38:02 AM »

John-
 <Where can I get more info on this solution? >
Well, you can ask SMC to deal with it. Or, you can get sucked into ham radio.<G>
 These "home computing" devices are supposed to be FCC ClassB certified to not cause interference in a home environment. I don't know if yours is a "home" device or an "office" device and, thanks to government logic, "office" devices only have to be ClassA certified which allows them to make MORE noise not less. This must be the only spec where getting an "A" means less than getting a "B".<G>
 There are lots of web sites you can turn up by searching on "solving RFI" or "reducing RFI" etc that should give you more info. If the SMC was emitting noise only via the power cord, then yes a choke (aka ferrite) might stop it. There are some technical issues about which kind from who might work better...that's where you wind up getting sucked into the hobby.<G> It might be easier, if that SMC runs on 9v-12v dc, to try running it from a gel cell or other isolated power supply first. If it still makes the noise--which it probably will--then looking into a choke on the power cord won't accomplish anything.
Logged
XYZZY
Member

Posts: 2




Ignore
« Reply #27 on: June 29, 2004, 06:53:40 PM »

Thanks for the advice. I think I'll try your "battery" solution first. If that doesn't help I may just buy another router - they're not that expensive now.
I'm also waiting for some feedback from SMC. Also, according to the documentation, this router is certified Class B.

John
Logged
KC2MMI
Member

Posts: 620




Ignore
« Reply #28 on: October 10, 2004, 05:36:37 PM »

Guys, after all these months the FCC still hasn't said "boo". (Although, perhaps they will on the 31st?)

But the ARRL's Laboratory Manager and RFI specialist, Ed Hare W1RFI, has shed some light on this.

"...above 30 MHz, the device has radiated emissions limits.  That is 100 uV/m 3 meters from the source, or +40 dBuV/m.  To put that in perspective, on VHF television, a "Grade B" signal on channel 2 is +47 dBuV/m so the signal from the unlicensed device is only 7 dB less than the TV signal in the clear. If that unlicensed device is being used indoors near a TV with rabbit ears, interference is inevitable."

Simply put, the FCC ClassB certification limit is apparently so high at VHF frequencies, that a ClassB certified device can and will squeal like a pig and still be in full compliance. The fact that most home computing devices create no problem at all, is apparently a credit to DEC, COmpaq, HP, IBM, and the many small shops that manage to build much more complex devices--which don't create any RFI at all.

And a further credit to those fine folks who say "HI! We're from the government and we're here to help you!"
Logged
W4DJ
Member

Posts: 4




Ignore
« Reply #29 on: September 07, 2007, 11:59:20 AM »

Yes I have a BEFSR41 and have the same problem here with RFI on 2 144 and 400 mhz.
I have tryed all the recommended fixes but its still there coming from within the unit, as soon as I pull the power plug the RFI is gone!
Logged
Pages: Prev 1 [2]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!