Folks,
How might incorrectly wired RJ connectors effect this condition. If the
correct pairing is not maintained I would expect that there
would be a higher level of radiation.
--
73 es God Bless de KK1L...ron (kk1l@arrl.net) <><
QTH: Jericho, Vermont
My page: http://www.qsl.net/kk1l
Jim Brown wrote:
> On Wed, 27 Jul 2005 15:17:48 -0500, Frank Brady wrote:
>
>
>>Greetings,
>>I've avoided this s5 to s7 noisy area at several QTHs, but now I've
>>rediscovered the joy of DX hunting recently and I hate to give up this part
>>of the 20m band.
>
>
>>I've asked other hams about this and many, but not all have experienced
>
> this.
>
>>I'm not looking for anything peculiar to my current (2nd floor apartment)
>>QTH because I heard it in our home and other apartments. The same sounding
>>interference is on the low end of 30m as well - around 10.106 to 10.108.
>
>
> 1. I am SURE that this IS Ethernet trash.
>
> 2. I believe it is 10BaseT traffic, which can occur on a 100BaseT connection
> if there are 10BaseT cards. Many cable modem and DSL modem outputs are
> 10BaseT.
>
> 3. The trash on 30m is also Ethernet, and you will also hear it at 21.052
> and at several places on 10 m.
>
> 4. You will hear multiple carriers with modulation on them when there is
> data transfer, and each of your neighbors will be on a slightly different
> frequency. I have wire antennas at the front and back of my city lot, and
> some carriers are stronger or weaker on each antenna, and on each band.
>
> 5. An effective FIX for this trash is to wrap the offending Ethernet cable a
> 6-8 turns around an FT-240-43 toroid AT EACH END of the Ethernet cable that
> is longer than about 5 ft, and at one end of shorter ones. That's because
> the two ends of the cable take turns talking, so the Ethernet cable radiates
> the trash as common mode. BTW -- shielding the cable will not be effective.
> (Common mode means that the cable is working as a long wire antenna.
>
> 6. The fix above will knock the trash down by at least 3 S-units for each
> offending source (that is, each Ethernet cable that you are hearing), but
> each birdie may be the sum of trash from several cables. And the fix will
> not touch the trash that is radiated directly from an unshielded box.
>
> 7. There may also be some common mode radiation from the power supply.
>
> 8. Start with your own house, fix it, then move to your neighbors after
> you've had the experience with your own system.
>
> If you would like to read more about this, see the publications section of
> my website for a presentation on this that I gave to my local ham club.
>
> BTW -- some other ways to minimize it are use the shortest Ethernet cables
> possible and run as much as practical of your system (and your neighbor's
> systems) on a WiFi link. The WiFi causes no QRN or QRM, but you will need to
> cool off the Ethernet cable that connects it to a cable modem, DSL modem,
> and other wired Ethernet connections.
>
> 73,
>
> Jim Brown K9YC
> http://audiosystemsgroup.com
>
>
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>
>
>
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