Creases in coaxial cables

mm wrote: > Are small bends, or even small creases, or even large creases enough > to cause internet signal degradation. IIUC, it can cause ghosts in tv > reception??, but with internet, it would mean the resending of some > packets, right. Perhaps multiple resending, lowering the speed by

10, > 20, 50, 80%????

When it gets to the point of causing data loss, you're already on the bad side of things.

1: Don't squash/crease your cables. You mess up the VSWR and cause reflections (ghosts in TV). You start getting data re-sends and you may get to the point where _no_ data is usable.

2: Bends are fine but don't get the radius too small. At least a 3" radius for RG-6 will cause no problems.

3: If the cable is coming through a wall from outside, keep a 'drip loop' so water doesn't run down the cable into the wall

Its not speed you need to be concerned with. If you're noticing speed losses it's WAY screwed up.

Once the cable is kinked/squashed/deformed or otherwise damaged, the length before or after the damage can be used but you REALLY don't want bad VSWR in the system. SO cut out any visibly damaged pieces.

For outdoor cable runs you need weather boots to cover the connectors. Compression fittings are better yet WITH the boots and I like to fill the connectionwith silicon grease to keep the water out. Also prevents corrosion.

You're welcome GG

As a rule, with digital transmission, flaws of the sort you mention are either not significant, or very significant, with no in between.

IOW, if it works at all, it'll work just fine.

Still, the smart money would be on buying a new roll of RG-6 at the local Radio Shack.

Isaac

Surely, the most significant factor is whether the OP is talking good quality twin screen coax, with specs up to the job for the carrier frequency that's being used by the cable company ? If it's 20 year old VHF patchlead coax, rather than proper distribution coax, any losses due to poor VSWR from kinking, will pale into insignificance. With the advent of DSB TV, good quality twin screen coax is now so cheap, that I can't imagine why you would not just use new, and be absolutely sure that you are getting the performance that your cable broadband is capable of delivering. The comments made by other posters regarding permanent damage and bend radii, are absolutely valid, and should be adhered to. With regard to crush damage, another factor which no one has mentioned, is that it can result in frequency-specific suckout. Trust me - I've seen it on a spec anny.

Arfa

Do you have some TV application that would let you test the cable, however imperfectly. Perhaps from VCR to TV, comparing your cable to a brand new 6' long cable. Not a perfect test as channels 3 and 4 are less than 100MHz but if the long cable is visibly inferior, you know you should scrap it.

But as others have noted, the RG # of the cable is all important.

You're probably good to go. I was fooling around with a Time Domain Reflectometer and some coax - shows changes in impedance along a length of wire and where the problem is by length.

A small kink, and even some pretty aggressive kinking, is usually not significant with solid or foam core coax. With spiral core (exotic stuff with a spiral of foam to center the center conductor) a kink can be significant. Most ordinary coax really has to be abused badly to start reflecting signal.

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Unless something's changed in a major way, smart money doesn't spend itself for coax at Radio Shack.

--
Asking Iran and Syria to help us succeed in Iraq is like your local fire
department asking a couple of arsonists to help put out the fire.
 -- Joe Lieberman

Definately. Radio shack is about twenty times more expensive than buying from a home construction hardware store.

Just make sure the percentage of shielding is 80% or better, the more the better.There is alot of off-air noise and signals that get into a modems' bandwith that can cause havoc.Not to mention your digital boxes and /or digital phone services.Moisture can also be a problem in coax which may not be visible when you are examing the cables.As for small kinks or bends, it may depend on what type of modulation is being used for the modem. A 16 or 256 Quam signal is extremely sensitive to cabling issues where as a Qspk isn't, so to speak. Instead of looking for a used cable , why not just ask a cable installer( if you happen to see 1 in your neighborhood) if he can give you some coax. Most would be happy to do so if it means they won't have to run it. Some Cable companies even sell it at some of their offices. A good quality coax will also keep you from causing problems throughout your nieghborhood sice it keep unwanted noise and carriers from entering the upstream path( and down stream paths in some cases).If and when you do get a cable modem installed , make sure the installer or whoever checks out your drop coax to make sure you are not putting excessive noise back onto the system, a good tech should do that anyway.

--
Dartattack

Yes, but not if you have to ship it.

RG6 is a specification including materials, dimensions, and yes it also includes the type and coverage of shielding. There's no such thing as

75% shielded RG6.

The RG standard is no longer used by the military so yo can use it any way you like. Radio Shack, Jersey Specialty Company, and others sell so call "RG 6 coax" that isn't fit for audio use because there is very little braid and no foil. You could marker lamp cord as RG6 and not worry about being charged with selling substandard cable.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

What a great idea (and should-be obvious idea to me who has often said, The way to know is to look.) I should have thought of this.

I'll do that.

It's labeled 200896 F677TSVV (ETL) us CATV 18 AWG .

Could you explain any of thta to me?

After my first post I remembered that I had cable tv for a few years when I moved in, and the cable guy scrunched up about 12 inches and stuffed it into a 3 inch box, with some pretty sharp bends. When I learned how bad this was, I can't remember which: either I didn't have cable anymore, or I would have complained, but the cable picture was perfect afaict. Regardless of the reason I didn't complain, the cable picture was perfect as far as I could tell.

If you are inclined to email me for some reason, remove NOPSAM :-)

Yeah, I'm sure, but a) I have to do something with this old cable or I'll end up saving it for the rest of my life. b) I'm over budget, on my whole life. I figure that 10 dollars not spent now will be worth a

100 when I'm 80 years old, and I'm going to need every penny by then.

If you are inclined to email me for some reason, remove NOPSAM :-)

Sorry - I don't have a clue as to what these markings mean.

mm wrote:

Was it neatly coiled inside the box, or hammered in? I used to leave an extra six inches for repairs and carefully lay it into the box, around the edge to prevent any kinks.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

No, it was stuffed in with pretty sharp bends, that took up only a fourth of the width of the box, iirc. I would have thought he did good if he did like you describe, around the box.

-- Sorry it took so long to reply. I left all the previous posts for context.

If you are inclined to email me for some reason, remove NOPSAM :-)

Thanks anyhow.

If you are inclined to email me for some reason, remove NOPSAM :-)