[Elecraft] Wireless Router Recommendations

[Jim Brown]

>that has been sitting as close as two feet from my K2 with no
>problems that I noticed.

Proximity to the radio is meaningless. The following comments 
apply to virtually ALL Ethernet devices, including your computers. 
What matters are:

1) The antennas connected to the Ethernet device -- their length, 
and their proximity to YOUR antennas (but NOT to your radio). 

2) The design of the device with respect to SHIELDING of its own 
internal wiring

3) The design of the device with respect to the internal 
generation of RF trash

4) The design of the device with respect to keeping whatever trash 
it produces off the antennas connected to it. 

5) The directivity of the ham antennas and the Ethernet antennas. 

Ah, you say, you don't connect antennas to it, only Ethernet 
cables and a power supply lead. And if it's a router, the Cable TV 
coax or DSL connection. But even though we don't call them 
antennas, they ARE antennas, and they will radiate whatever RF 
trash they carry just like any other antenna. 

I have yet to find a piece of Ethernet gear that doesn't put out 
trash on the ham bands. Some are worse than others, and Linksys 
has been viewed as really bad. But when I switched to Netgear 
switches to get rid of noise, I noticed no difference!  

MOST of the noise in the equipment I've tested comes out of the 
box as a COMMON MODE signal, and is radiated by those cables as if 
they were a long wire antenna. The good news is that the noise can 
be greatly reduced by winding some turns of both the Ethernet 
cables and the power supply cables around the RIGHT ferrite 
toroids. Once you do that, you're left with what comes out of the 
box due to poor shielding. And, of course, whatever is radiated by 
your neighbors systems that are close enough to your radio 
antennas to be loud enough to hear. [You can identify 10BaseT 
Ethernet as the source by listening around 10,106 kHz, 10,120 kHz, 
14,030 kHz, 21,052 kHz for strong carriers with some subtle 
modulation. While we buy 100BaseT gear, it carries both 10BaseT 
and 100BaseT traffic, and most routers and modems talk 10BaseT. 
These carriers are not based on a clock with a tight frequency 
tolerance, so every system is running on a slightly different 
frequency. That's why, for example, you will hear carriers between 
about 14,029 and 14,030.5 kHz.]  

I just moved from a city lot in Chicago (neighbors 15 ft from my 
house in every direction) to a rural area in CA (one neighbor 250 
ft, another 350 ft, others at least double that). In Chicago, my 
ham antennas were all within 20 ft of Ethernet cables. Here in CA, 
the closest ones are at least three times that distance. In 
Chicago, I could get my own trash down to a bit above the noise 
level, but I still heard my neighbors loud and clear. Here in CA, 
I don't hear anything from these Ethernet systems, even though my 
noise level on the ham bands is way down too! 

There is a detailed tutorial on ferrites on my website, along with 
presentations I've done to a couple of ham clubs. All can be 
downloaded as pdf files. No cost, no cookies. 

http://audiosystemsgroup.com/publish

BTW -- shielded Ethernet cable doesn't help -- for the shield to 
do anything, it would need to be connected at both ends, and you 
would be hard put with these boxes to find a connection that meant 
anything. 

73,
Jim Brown K9YC