[RFI] Filtered connectors for video cable
Thu, 25 Oct 2001 21:34:22 -0500
I have had good luck with video cables from Hurricane Computers (see link
below). The cables are billed as being triple-shielded and come in various
lengths. I have used their 10', 15' and 20' video cables for various of my
customers, and have had very good results. Good noise supression and good
video quality. Here in my shack I replaced an old cable and extension cable
with a Hurricane 10' extension cable and cleared up a host of problems.
At their web site, look under "cables" and then "monitor".
Wes - N5WA
From: email@example.com [mailto:firstname.lastname@example.org]On
Behalf Of Pete Smith
Sent: Thursday, October 25, 2001 3:55 PM
Subject: Re: [RFI] Filtered connectors for video cable
At 01:12 PM 10/25/01 -0700, Eric Gustafson guest account wrote:
>I'd go ahead and make the sniffer...
>Are the monitor and computer powered from the same wall socket?
>The physical separation of the monitor from the computer is not a
>good idea from an RFI standpoint. But I suspect this
>circumstance is merely making the "real" problem worse. Ideally,
>the units should be near one another and powered from the same
>power strip to avoid efficiently coupling circulating RF currents
>into the house power wiring.
>The worst possible scenario is a large physical separation with a
>video cable whose shield integrity is not maintained and a power
>distribution system that has power arriving at the monitor via a
>separate circuit than the one by which it arrives at the computer
>(separate wall outlet is bad enough but separate circuit -
You have hit on something. They are currently separate circuits -- don't
have to be but are now. I can fix that. The monitor has an AC line filter
on it -- supposedly rated for 30 dB attenuation at HF. You'd think...
>By shield integrity, I mean that the shield fully encloses all
>the wiring all the way from (metal) panel to panel. Connectors
>that terminate the shield to the shell by a single wire
>connection rather than having the shield bonded all the way
>around the shell (and fully enclosing all the signal wires) do
>not count. These devices are more properly described as "antenna
>feedpoint" than as shielded connector.
>Two cables in series are a bit dangerous but not necessarily a
>fatal flaw _IF_ both cables are properly constructed as per above
>_AND_ the shield integrity is maintained where they plug together
>(and where they connect to the equipment - don't forget to
>tighten up the jack screws).
>Unforunately, many computer store aftermarket cables are not well
>constructed. So if you do determine that you have a video cable
>shield integrity problem (using your sniffer), you will need to
>do a bit of shopping for a well made cable. Companies like "Black
>Box" and others have the capability to make good cables and
>identify them as such. If you have to go to that trouble, you
>may as well get a single cable that is long enough to do the job.
Yes, I'm sure you're right. That's a good lead on Black Box.
>Most (but not all) of the cables I've gotten with monitors or
>computer systems from the big players have been correctly made.]
The monitor is a Micron, but I'm sure that the cable that makes up the
first 6 feet from the computer outward is aftermarket crud. I'm off to
sniff the cables...
73, Pete N4ZR
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