[TenTec] notch filter for Eagle?
w2iy at verizon.net
Thu Jul 20 13:48:07 EDT 2017
Bingo. There is a router about 6 feet away from the laptop/xvcr setup and I
am using Ethernet cable (wired) connection to it. I have ferrites on both
ends of the cable but I can see how this might not be enough. I will
experiment with turning of the router later when the rest of the family is
off line :) Will also be interesting to see if all those other carriers I am
hearing are coming from the router too.
From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Jim Brown
Sent: Thursday, July 20, 2017 1:29 PM
To: tentec at contesting.com
Subject: Re: [TenTec] notch filter for Eagle?
On 7/20/2017 7:38 AM, Joe Papworth via TenTec wrote:
> Those carriers around 14030 may be from a wireless router.
More precisely, they are leakage from wired Ethernet systems. Wired
Ethernet uses a free-running clock that is synchronized with the
Ethernet Hub or Switch; we typically hear our own system and those of
close-in neighbors. When I lived in Chicago with houses spaced about 40
ft, I typically heard 3-5 of them spaced from about 14029.5 to about
14030.5. There are other clusters on 15 and 10M. It's easy to figure out
which signal is coming from your system by killing power to the
These signals are radiated by the Ethernet cable, and can be suppressed
by winding the Ethernet cable through a ferrite core to form a common
mode choke, following the guidelines for RG8X-size cable in
k9yc.com/RFI-Ham.pdf Virtually all WiFi access points and cable/DSL
modems include an Ethernet port, so their wiring also radiates this trash.
Note also that both the computers and the Ethernet Hub/Switch/Router are
sources of this noise, so if the wired Ethernet cables are longer than
about a tenth of a wavelength, a choke may be required on both ends.
Even better, avoid Ethernet by using only WiFi, so the only noise source
is that Router/Modem. The cable(s) interconnecting them will be shorter,
hence poorer antennas, and they will be the only ones you need to choke.
73, Jim K9YC
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