My guess is that it is likely easier to do the right thing with the liquidtight conduit.
In a high rf environment one of the best things you can do is to create a faraday cage consisting of the metal enclosure, the shield around the cat5 cable and the radio shielding/metal enclosure. If the shield is continuous, then the rf signal won't be able to enter the twisted pairs themselves. In a shielded cat5 environment, you have to take care that the shield itself is terminated at the entry of the metal enclosure. This is either accomplished though stripping the shield back and connecting it directly to a metal clamp of some sort at the entry point, or some sort of grounded shieled waterproof feedthrough coupler. If you use a metal conduit all the way from the box to the radio, this faraday cage will largely be automatically generated, especially if the radio is in a metal enclosure such as a 450i. Even if the radio isn't in a metal enclosure, as long as the gap is very small, you'll end up with much of the same benefits. If you are using a metal enclosure for your electronics, one of the worst things you can do is to bring the shields inside the metal enclosure without grounding them at the entry point. The shields can become little reradiating antennas inside the enclosure if you don't ground them at the entry point. My preference at high rf sites is to ground the shield at a metal enclosure, and use unshielded cable inside the enclosure. Adding a ferrite bead just inside the enclosure can help to filter out any remaining rf. On Fri, Jul 20, 2018, 7:35 PM Nate Burke <[email protected]> wrote: > I'm curious why Liquidtight works when the foil shield on the Cat5 > doesn't. Extra distance from the twists? Heavier gauge steel? Do you > need to make sure the liquid tight is grounded, or just the fact that it's > around the cat5 is enough? > > On 7/20/2018 7:04 PM, Chuck McCown wrote: > > Yeah, that too. Some folks could not make it work without the > liquidtight. > > *From:* Sean Heskett > *Sent:* Friday, July 20, 2018 5:38 PM > *To:* AnimalFarm Microwave Users Group > *Subject:* Re: [AFMUG] Ethernet problems next to FM Antenna > > Put all Ethernet cables inside shielded liquidtight flex conduit. You can > buy it st an electrical supply shop. > > Be sure to run the conduit to a metal box at the top and then breakout to > each ap in smaller shielded conduit. > > -sean > > > On Fri, Jul 20, 2018 at 10:35 AM Nate Burke <[email protected]> wrote: > >> It looks like the old archives aren't back online yet, so I couldn't go >> searching through there for ideas. >> >> I have a site where we have been co-locating with a 800w FM Transmitter >> for years. We've always had Ethernet problems at the site since the FM >> went in. Everything is shielded cat5 (Belden 7919). It is at a grain >> elevator, our equipment is on one corner of the platform, and the FM >> Transmitter is on the other corner. We are horizontally separated by >> about 10 feet. There is no way to get vertical separation. I used to >> run all the cables down to the bottom of the leg, about 100'. In an >> effort to make the Ethernet work better, I installed an Edgepoint fed >> with Fiber at the top, so cable lengths between the radios and the >> Edgepoint are now 5'-10'. With the FM Transmitter turned off, everything >> runs perfectly. When the FM is turned on, most equipment drops to >> 100mb, and some goes down to 10mb. On the most problematic equipment, I >> have installed the 4 pair FM Filters from Sandman >> http://www.sandman.com/rf.html within 12" of both the switch and the >> radio. It made no change. >> >> What FM Elimination tricks have I forgotten to try? I was really >> expecting the short cable lengths to solve the problem. >> >> -- >> AF mailing list >> [email protected] >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> > ------------------------------ > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > > > > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com >
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