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[RFI] Broad band Cable Modem

To: <rfi@contesting.com>
Subject: [RFI] Broad band Cable Modem
From: wa2bpe@infoblvd.net (WA2BPE)
Date: Sun, 02 Jun 2002 18:17:09 -0400
Check the cable setup carefully despite what the cable company says it has
done.  Another local who does a lot of monitoring of various services found
many bad connections + he was experiencing tremendous interference which
was traced to the cable modem.  Seems that the modem manual (he found it -
on-line - the cable company provided no information) required a
"...shielded cat 5 cable... to be provided by the provider...".
Eventually, after denying that they existed, they managed to come up with
one with interference dropping markedly.  The point here is that this *may*
be where your signal is getting into your neighbor's system.

I would not expect the cable company to provide much help; most would
rather blame the HAM or hope that it will go away.  This problem seems to
be driven by economics and little or no experience with/understanding of
EMI.   If I can find it, I will pass on a url which points to a cable trade
journal and a white paper on amateur radio signals and cable systems.

Please keep us all informed as to your progress/solution/results.


Tom - WA2BPE

"Elbert E. Flanagan" wrote:

> Would appreciate any comments or fixes you can recommend concerning RFI
> into a neighbor's computer- a new 1.6 gigahertz. The location is within
> 50 feet of my radio hamshack.  The problem mainly appears when I run
> Radio Teletype  at low power, 50 watts or less on the 30 and 40 meter
> amateur bands. Other modes does not appear to cause the problem,  RTTY
> is a constant carrier transmission type. No problems experienced in my
> residence on TVI, telephones (including wireless) and stereo equipment.
> The cable TV company has updated all coax cables , not because of my
> problems but to be digital capable.  I understand others have had
> similar experiences.
> The external modem with AC power supply, shuts down-- no other problems
> experienced with the computer normal operation.  I have provided an EMI
> ac line filter for the modem power source which helps but not a cure..
> Thanks    W8RHS
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