Topband: 160m noise
marc.wullaert3 at pandora.be
Thu Nov 4 03:58:14 EST 2004
I use also a linksys 4port and wireless G 2.4hgz router.
No problem here but I did have to change the power supply.
I have CAt 5 (FTP) cable installed in the house and use
also the wireless port for a laptop .
----- Original Message -----
From: "Garry Shapiro" <garry at ni6t.com>
To: "Topband Reflector" <topband at contesting.com>
Sent: Thursday, November 04, 2004 3:41 AM
Subject: Topband: 160m noise
> I modified a 100 kHz Loran loop to 1.85 MHz, mounted it on ski racks on my
> car and cruised the neighborhood looking for low frequency noise
> sources---those rolling off below 4 to 7 MHz, which are not usually
> to be due to power company hardware. The loop exhibits a very sharp null,
> which I have not previously had the use of in tracking 160 noise.
> I found that most poles with transformers--and ground wires to the
> transformer--are radiating, but that they vary greatly in amplitude. Some
> these sources appear perhaps to emanate from telephone lines (!)---ADSL?
> the big surprise was to return home and get a huge indication from....my
> shack. The source was my LInksys 4-port Router/Switch---or the Network
> Interface Cards (NIC's) in the computers. The noise appears to be common
> mode radiation remanating from the CAT 5 cables connecting the computers
> the router/switch.
> I presume--but cannot be certain--that the CAT 5 cables, consisting of
> twisted pairs, are reasonably balanced at 1.8 MHz. If this is a reasonable
> presumption, the radiation must be due to source or load impedance
> in either the NIC's (the same in each computer) or the Linksys
> router/switch. The cable radiation is picked up by my antennas, a
> based upon:
> * the radiation is detectable >>100m away.
> * the resultant interference is somewhat different with each lowband
> My problem is that I cannot conclusively identify the NIC or Linksys as
> culprit without wholesale substitution. My inquiries to Linksys have
> resulted in the usual nonsense one receives from "Technical Support" (sic)
> from vendors. In this case, Linksys regurgitated Part 15 back to me and
> suggested a firmware upgrade (!) This is reminiscent of outsourced foreign
> tech support people telling you to reboot Windows. I do not seem able to
> convince them that this is a hardware problem.
> Has anyone on this reflector experienced a similar problem? Can anyone
> some insight --specific or general--re signal performance of NIC's or
> routers in this context?
> I ask this before replacing both the NIC's and the router.
> Garry, NI6T
> Topband mailing list
> Topband at contesting.com
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