[Moon-Net] Ethernet Interference

Cliff Sojourner cls at employees.org
Sun Sep 8 05:41:19 CEST 2019


ok, look, ethernet comes in 3 speeds: 10Mbps, 100Mbps, and 1000Mbps.  
they all emit different birdies.  I don't find many 10Mbps devices 
running  these days, although I am sure some of you cheapskate OMs have 
Windows 95 systems running :)  jiust a few 100Mbps devices, mostly Gbit 
devices.  They have a telltale birdie on 14.212, and +/- 50? KHz harmonic s.

Cat5 and Cat6 UTP is most common wirng.  it is 4 twisted pairs, 100 ohm 
impedance per pair  why are the pairs twisted? because they are a 
transmission line.  Do transmission lines radiate? No.  Cat5 UTP is not 
an antenna.

Some of my older routers and switches emitted so much RF st the 
drivers., the RJ45 jacks...  The only real  cure is to buy new ethernet 
devices,  In good metal cases.

Yes, put toroids on the ends of the Cat5, that will help at the point of 
radiaion, the ethernet jack.  And isolate in metal boxes or wrap in 
aluminum foil.  or both.

Unfortunately the DSL installations I am familiar with seem to be top 
quality and apparently emit no RF.  Although I know people have 
complained about it before. Cable modems these days are pretty quiet, 
even at the ethernet RJ45s.  75 ohm RG6 doesn't radiate, that's for sure.

PS, don't use Cat 6 or h9igher for homes.  It's intended for datacenters 
and is overkill for homes..

PPS all BaseT (RJ45 jacks) ethernet uses one pair fo0r rx, one pair for 
tx. two pairs are available for ...  anything you want. I'm enjoying 
"Power over Ethernet" (PoE) which allows a small amount of ipowqre for 
the device on the end.  Lots of possibilities there...

73, Cliff K6CLS CM87


On 9/7/19 5:15 PM, Edward R Cole via Moon-net wrote:
> Thanks, good reference.
>
> I use a #43 core to wrap the output of my 50v switching PS.  I use 
> No.10 wire and run both Pos and neg three times in bifilar wrap. 
> Absolutely no PS noise on 6m.  I got the tip from W7GJ who has used 
> the same PS in several 6m sspa for eme.
> http://www.kl7uw.com/6m_control_panel_back_3.jpg
>
> You might note the two clamp-on cores on the 240vac leads (just added 
> for a little insurance).
>
> 73, Ed - KL7UW
>
> At 03:03 PM 9/7/2019, Jim Sanford via Moon-net wrote:
>> Try this:
>>
>> http://www.w5zn.org/files/Slaying%20the%20Grim%20Reaper%20of%20Internet%20Router%20Noise%20on%206%20Meters.pdf 
>>
>>
>> I haven't "treated" every ethernet spigot, but this has made a 
>> difference.
>>
>> Good luck & 73,
>>
>> Jim
>>
>> wb4gcs at amsat.org
>>
>>
>> On 9/7/2019 3:17 PM, Edward R Cole via Moon-net wrote:
>>> Trevor,
>>>
>>> A few years ago I tried reducing 2m birdies and tried some clampon 
>>> ferrites with no noticeable improvement, but then I bought some Cat6 
>>> shielded cable jumpers which did help a little.  My main internet 
>>> cable is 25-foot of cat5e from another room that has the router, so 
>>> that might still radiate some.
>>>
>>> Most of my birdies were RF from surrounding area coming in antenna 
>>> cables.
>>>
>>> BTW I am using Cat6 shielded cable with my digital angle encoders on 
>>> my eme antennas which eliminates RFI to my digital display.
>>>
>>> 73, Ed - KL7UW
>>>
>>> At 10:22 AM 9/7/2019, MR TREVOR DUNNE via Moon-net wrote:
>>>> Hi All
>>>>
>>>> I seen a post somewhere recently explaining that it was a waste of 
>>>> time putting ferrite on either utp or stp Ethernet cables, I can't 
>>>> remember which, or where I read it, I am trying to remove some 
>>>> birdies on 2m caused by home network,
>>>>
>>>> Anyone have any pointers, I have a large amount of cat cable around 
>>>> my house so don't want to replace it with the wrong type,
>>>>
>>>> Thanks
>>>> Trevor
>>>> EI2GLB
>>>> _______________________________________________
>>>> Moon-Net posting and subscription instructions are at 
>>>> http://www.nlsa.com/nets/moon-net-help.html
>>>
>>> 73, Ed - KL7UW
>>>   http://www.kl7uw.com
>>> Dubus-NA Business mail:
>>>   dubususa at gmail.com
>>> _______________________________________________
>>> Moon-Net posting and subscription instructions are at 
>>> http://www.nlsa.com/nets/moon-net-help.html
>>>
>>
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>
> 73, Ed - KL7UW
>   http://www.kl7uw.com
> Dubus-NA Business mail:
>   dubususa at gmail.com
>
> _______________________________________________
> Moon-Net posting and subscription instructions are at 
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