[RFI] Xfinity Router RFI (Xfinity router name XB3)
Jim Brown
jim at audiosystemsgroup.com
Thu Feb 13 12:37:00 EST 2020
This is a very interesting post, Don.
Your loop and a description of your troubleshooting would make a great
piece for QST or NCJ. Also, spectrum pix would make a great addition to
NK7Z's collection of the signatures of known noise sources.
For chokes wound on the 2.4-in o.d. #31 cores, I suggest following
recommendations for THHN for cables like AC line cord and RG400 for
smaller cables in the New Cookbook.
73, Jim K9YC
On 2/13/2020 6:59 AM, Don Kirk wrote:
> Hi Jim (and gang),
>
> I should also mention the wireless router we are talking about is really
> called a Residential Gateway.
>
> The Xfinity Telephony Gateway provides four Ethernet connections for use
> as thehub of your home/office Local Area Network (LAN). The Xfinity
> Telephony Gatewayalso provides 802.11a/b/g/n/ac wireless connectivity
> for enhanced mobility andversatility. In addition, the Xfinity Telephony
> Gateway provides for up to two sepa-rate lines of telephone service and
> Digital Enhanced Cordless Telecommunications(DECT) funtionality to allow
> using cordless telphones within the home. The Tele-phony Gateway also
> offers integrated MoCA 2.0 home networking providing Inter-net access
> and transfer of multimedia content between devices over coaxial cablein
> the home.
>
> Just FYI,
> Don (wd8dsb)
>
> On Thu, Feb 13, 2020 at 9:40 AM Don Kirk <wd8dsb at gmail.com
> <mailto:wd8dsb at gmail.com>> wrote:
>
> Hi Jim,
>
> Thanks, but I really wanted to know if others have noticed a 1 MHZ
> wide signal that has a white noise waterfall and spectrum plot (both
> RF and Audio) from the Wireless Router I mentioned centered around
> 21 MHz. The main reason I asked this question is that it took us a
> couple of days to track down the source because at times we had
> conflicting bearings from our numerous direction finding antennas
> and I now suspect we ran across similar signals originating from
> other homes in a pretty densely populated neighborhood.
>
> This case made me introduce a new portable direction finding antenna
> to my toolkit for HF which turned out to be a life saver. I have a
> lot of experience with small terminated flags and pennants on 160
> meters, and this gave me the idea to design and build a very small
> portable terminated flag that I designed to have a cardioid pattern
> all the way up to at least 30 MHz, and this antenna was a great help
> due to its unidirectional properties. Used this portable flag (2
> foot x 4 foot) with a W7IUV preamp operating off a 9 volt battery
> and this system was invaluable. A big advantage of the terminated
> flag is that it's truly broadband versus the portable tuned loops we
> also used. Having the broadband antenna allowed us to easily see
> the 1 MHz signature of the signal. (where it rolled off, etc.).
>
> Please keep in mind that when we are dealing with a homeowner that’s
> also a stranger that’s not a ham we should try and be the least
> invasive and least time consuming as possible while still obtaining
> the end goal which is to eliminate the RFI we are experiencing. We
> got lucky that this particular homeowner immediately volunteered to
> shut off his breakers before we even asked him to do that until we
> found what circuit was generating the noise, and then he went into
> his master bedroom and started unplugging devices until the device
> generating the noise was located (Mike and I did not enter his
> home). He then mentioned he was going to go to xfinity on Monday
> anyway and would request a new wireless router. It also helped that
> this homeowner had some knowledge of who Mike was and he mentioned
> that he had gone to high school with Mikes son many years ago.
>
> As I already mentioned we indeed will have the home owner try a
> toroid choke (based on the 31 material) on his AC line cord as well
> as a traditional differential mode power line filter if new
> equipment from Xfinity does not solve the problem. If these methods
> don’t work then we will dig deeper (chokes on other cables entering
> and exiting the wireless router, etc.).
>
> On a side note, Mike (W9RE) is going to give the homeowner an
> extension cord wrapped on our 31 material toroid core to try on his
> existing router prior to this weekend since Mike as I'm sure you
> know is big contester and he sure would like to have his 15 meter
> noise reduced (or eliminated) for this weekends contest, but again
> we are not trying to be too over bearing on this homeowner since he
> has already been so cooperative.
>
> Will post an update in the near future.
>
> Thanks and 73,
> Don (wd8dsb)
>
>
>
>
> On Wed, Feb 12, 2020 at 9:39 PM Jim Brown <jim at audiosystemsgroup.com
> <mailto:jim at audiosystemsgroup.com>> wrote:
>
> On 2/12/2020 6:18 PM, Don Kirk wrote:
> > If the replacement router does not fix the problem then
> > Mike will test a toroid core choke as well as a corcom type
> filter on the
> > wireless router power cord.
>
> It's ALWAYS a good idea to put a suitable ferrite choke on any
> wiring
> connected to a noise source -- it's usually those wires that
> radiate the
> noise. And that includes the AC line cord or DC power cable. For
> 15M,
> I'd start with three turns on a medium-size #31 clamp-on, and
> I'd do the
> same with any Ethernet cables.
>
> If you haven't already done so, I'd try to shift the network to
> WiFi, so
> that the only cables are the power supplies, the cable between
> the modem
> and the router, and the DSL or internet cable feeding the modem.
>
> Lots of detailed advice on my website in the piece about increasing
> contest scores by killing noise. k9yc.com/publish.htm
> <http://k9yc.com/publish.htm>
>
> 73, Jim K9YC
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