[Ham-Mac] ethernet hash

[Steve Hellyer]

Hi Chris,

Rick answer also solved my Ethernet noise problem for me. (My computer is about 2 feet from my radio.)

Make no mistake Ethernet is an RF signal when it used over copper 10/100/1000 base-t and it's designed to work over unshielded twisted pairs. This makes for a rather ideal antenna. Shielding might help but then you're changing the impedance of the wire and shorting it transmission length. Remember copper based Ethernet is tuned to unshielded impedance wiring but you have a short distance it may not be a problem. If you add toroid cores you will also effect Ethernet performance and/or distance. (You might not be as concern about that.)

Not sure the frequencies as it depend on what is negotiated 10/100/100 but if you look at the specs for unshielded twisted pair Ethernet wiring they are rated in Mhz.  http://en.wikipedia.org/wiki/CAT_5  The terms used are very similar to what we use in HAM radio world.  BTW: Higher CAT level 5, 5e, 6, 7 won't help as it just the grading, better copper purity and more twists per foot to handle the high bandwidth needs of faster networking over a distance.

By switching to Wifi you remove that copper wire antenna typically close to your HAM radio gear, transmit in high freq. like 2.5 Ghz or 5 Ghz, and are using a system design to limit it's TX/RX to those frequencies. Much higher level of "shielding" so to speak both in/out. You also typical turning off power to Ethernet which is the transmitter on the copper wire.

Don't think it's your Power over Ethernet (PoE) as that is DC http://en.wikipedia.org/wiki/Power_over_Ethernet
but it the AC/CD brick that power the PoE might cause some noise.  Many do as they are switch power supplies.

Your problems are tricky to solve but my advice is to try and use WIFI as much as you can and then move any copper based ethernet wiring away from your HAM gear and antenna as much as possible.

Sorry not the bullet proof fix but every situation is different and you have to explore options for your situation and gear.

One option might be to set Ethernet on computer to fixed speed rather than using the auto negotiation to highest speed. 
Just make sure you set all the device the same.  Won't eliminate the RF but it might change frequency you getting noise from to a place you don't listen to on HAM bands.

Btw. before we had 10base-T copper Ethernet we used 50 ohm RG-58 for Ethernet. We used to call thick and thin Ethernet. 10base2 :-) http://en.wikipedia.org/wiki/RG-58

In a sense Ethernets roots are showing up on your radio as noise. :-(

73
Steve -VA3SPH

On 2010-02-03, at 11:57 AM, Rick Prather wrote:

> Chris,
> 
> I have the same problem.
> 
> I am connected via a U-Verse router hooked to the phone line.
> 
> I eliminate it by doing as you say, unplugging either end of the Ethernet cable.  I use Wi-Fi, which the U-Verse router has built in,  instead and except for some nasty birdies from my laser printer which I turn off when I'm on the air, I am birdie free.
> 
> Rick
> K6LE
> 
> 
> On 2/3/2010, at 7:42 , EZ Rhino wrote:
> 
>> HI David,
>> 
>> <snip>
> 
>> What really gets me with all this:  Why doesn't every ham with ethernet/internet and a radio have this problem?  I wonder how many have this and don't know it.
>> 
>> Chris
>> 
>> 
> 
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