Quality

[binney]

What is the difference in quality for low voltage, such as RG-6 and Cat-?

I'm looking at some RG-6

Inner conductor .040" Copper Clad Steel
Dielectric .180" PE FOAM
Outside Dia. over foil .185"
Braid 60% aluminum wire
Jacket thickness .039"
Jacket outside dia. .27"
Impedance 75 ohms
Velocity of Propagation 70%
CAPpF/FT 15.7

Is this goog, bad, what's the difference? If any?

What about Cat-5E? Is all cat 5E the saome??

 

[kiloamp7]

Re: Quality

I dont know much about "datacomm". But RG6 is coaxial cable. Isn't that a different animal from Cat 5E ?

 

[binney]

Re: Quality

Cat 5E is phone/networking cable. The reason I'm asking about these 2, is, I've found a wholesaler who is selling me cat5E and rg-6 at almost 1/2 the price I was paying.

 

[mkoloj]

Re: Quality

Even within one manufacturers product line there is sometimes different grades of cable, there is "premium Cat 5E" and "standard Cat 5E".
There is a difference of almost 100% in price between plenum and riser-rated communications cable. The performance standard of Cat 5E is just a mininum just like the NEC for electrical work. Some manufacturers exceed the mininum by a little some by a lot. Some of the lesser quality cable takes more time to teminate and pull which if you are doing a job with 15,000 lines it will make a big difference in labor as opposed to wiring someone's house with 15-20 lines.
Why not get a reel or two and compare to the current product you are using and paying twice the amount for?? If you have a tester available that tests for things like Attenuation, NEXT, ELFEXT you can compare the numbers.

[ May 05, 2005, 09:21 AM: Message edited by: mkoloj ]

 

[petersonra]

Re: Quality

There are also manufacturers who sell different grades of cable that are identical, made on the same machines, to the same specs. They just market some as premium cable at a premium price, but other than the packaging it is identical.

Keep in mind that any good quality cable will work but regardless of how good the cable is, a poor termination will give you fits. Worry about getting the terminations correct is more important. get a good tester. you will be amazed at the difference in quality of connections made by different people that look identical.

 

[hbiss]

Re: Quality

The specs you give for RG-6 are going to be typical for any RG-6. If they weren't it wouldn't be RG-6. It's like quoting specs for a 2x4 and asking if it's any good. What counts is the quality of materials and construction- something you won't get from specs alone.

You get what you pay for and it pays to stay with products from major manufacturers. Unknown "bargains" like this can be anything from shorts of a quality product, something that didn't meet specs in one way or another or just plain junk.

I once bought some 4 pair CAT3 cable only to find that the pairs were twisted like CAT5. Seems it was born as CAT5, didn't meet CAT5 specs for some reason so they unloaded it as CAT3. Not the end of the world (unless you hate CAT5 like I do) but it does go to show what goes on. This was obvious, but what about something like the jacket or conductor insulation not being formulated properly or not of a uniform thickness? Would you catch that?

In short I wouldn't gamble just to save a few dollars. Once it's in the wall it's all over and I wouldn't want to be responsible if there is a problem down the road. Stick with name brand stuff.

-Hal

 

[mkoloj]

Re: Quality

Why do you hate Cat 5 so much Hal?
Didn't you know it is the solution to all of the worlds wiring needs ?

 

[jrdsg]

Re: Quality

my $.02 worth...

we use quad-shield RG6 exclusively in our home theatre and infrastructure projects as it better supports high-frequency satellite distribution. connectorization quality is also very important here, as poor termination can render good wire useless.

as for C5e and above, likewise installation and termination is at least as important as the brand of cable you buy. we aren't married to any particular brand but have had good results with Hellerman-Tyton terminations and LG, Mohawk, Genesis, and other brands. The cable-delivery mechanism [usually a box] really matters, since kinks are a real problem. Look for good kink-free reel boxes to pull from.

 

[hbiss]

Re: Quality

we use quad-shield RG6 exclusively in our home theatre and infrastructure projects as it better supports high-frequency satellite distribution.

Hate to tell you but you are wasting your money. Don't know where you came up with quad shield "better supports high-frequency satellite distribution". The extra shielding in quad shield is just that and has NOTHING to do with cable attenuation. There is RG-6 that is swept to 2500Mhz for sat distribution use and it can't even be had in a quad shield version. If it were necessary someone would make it.

Quad shield is intended for CATV use where there is unusually high RF fields such as in close proximity to a TV transmitter or where leakage from the cable is especially important to minimize such as near airports.

Leakage and ingress which sometimes can be an issue at CATV frequencies (as above) just is not an issue at sat frequencies and a quad shielded cable is a waste of time. A quality RG-6 or RG-11 with a 60% braid over bonded foil and a foamed poly dielectric is all you need.

If you do want to go that extra step get DBS cable that is swept to 2500Mhz. DBS cable is no different other than it is tested and certified to meet specs to 2500Mhz. Regular cable (including quad shield) is only tested to 1000Mhz because that is the limit of CATV frequencies. That doesn't mean they won't work for sat, only that they haven't been tested at those extended frequencies. Most sat installers use regular cable anyway without regard and with no problems.

-Hal

 

[jrdsg]

Re: Quality

thanks for clarifying that, hal. you are correct, the benefit of running quad shield is not so much that it has higher bandwidth as that it is better protected against interference from rf sources.

i shouldn't have been so lazy in that post.

that being said, we have experienced significant improvement in the signal quality delivered in this type of installation by changing to qs cable along with the use of higher quality termination gear and attention to quality control in the terminations themselves.

satellite dish installations seem particularly vulnerable to signal path problems, but this may be due to the added complexity of the signal path as it goes through more pieces of equipment on the way to the display device than CATV typically does.

consider me chastened, hal.

 

[petersonra]

Re: Quality

I think you hit the nail on the head when you mentioned a better quality termination. I suspect that when peopel go to the troule to spend the money on expensive cable and temrinals that they also buy good quality tools to make the terminations with.

The termination is by far the most common point where you have issues.

[ May 15, 2005, 12:29 PM: Message edited by: petersonra ]

 

[mdshunk]

Re: Quality

Please educate me on a quality termination. I've been using snap-n-seals with the SNS tool. Is this one of the preferred termination materials/methods, or is there something better? Also, is there a piece of cable test equipment that would be cost effective and make sense for a regular electrician to own?

 

[hbiss]

Re: Quality

Snap-n-Seals are fine but in my opinion they are overkill for most work we would do since they are designed for outdoor use. (If you are a cable company then it's another story). They are also costly. I think their popularity with the electrical trade is due to their availability through electrical and security supply channels where traditional (and more cost effective) hex crimp connectors and tools are available mostly through CATV supply distributors.

A connector is only as good as the way it has been installed. Make sure you prep the cable correctly and use the proper crimp tool.

As for test equipment, there isn't any simple and cheap VOM type piece of equipment. All are costly and all require that you have some knowledge of television and CATV frequencies, transmission and distribution to be of any use. I always recommend that unless you are willing to spend some time learning a new trade just run the cables and let someone else who knows the business do the rest.

-Hal

 

[mdshunk]

Re: Quality

Originally posted by hbiss:
A connector is only as good as the way it has been installed. Make sure you prep the cable correctly and use the proper crimp tool.

I appreciate that response. Can you elaborate on cable prep a bit? I have been using the type of tool that has two razor blades with tiny set screws for "up/down" adjustment that you spin around the cable. Is this the preferred tool? Is there anything else to know with respect to cable prep on RG59, RG6, and RG11 cable types that an electrician runs into on a regular basis? Any common recurring problems that are examples of poor RG6 terminations? Yes, the SNS connectors are pricy, but the local cable company almost immediately cuts off the hex crimped ones at the first trouble call they get before any testing has been done (Comcast) and installs snap-n-seals. This is why I switched. I have observed their men doing this first hand. Never have I observed any of their connector replacements (among the ones that I've hex crimp terminated) to have had any appreciable effect on the original problem. I switched to SNS just to keep the cable guys from making me look like an azz to my customers.

Expanding my horizons. Thanks.

 

[hbiss]

Re: Quality

... the local cable company almost immediately cuts off the hex crimped ones at the first trouble call they get before any testing has been done...

That's because they use SNS's exclusively and any other connector means it wasn't installed by them. If it wasn't installed by them they have found that 99.9% of the time there is going to be a problem with it, so to save a lot of time they just replace the connectors first as a matter of course. They probably don't replace your SNS's because there is no indication they weren't theirs. There is no reason to believe that SNS's can't be improperly installed either.

There is no difference in performance between properly installed connectors. Apparently Comcast has standardized on SNS's, nothing wrong with that nor is there anything wrong with hex crimps which are used by many other cable companies. I would say that when in Rome do as the Roman's do and use the same materials as Comcast, either that or leave the terminations up to them, especially if it is going to cause problems.

There are all kinds of cable prep and stripper tools out there, some work, some don't strip the cable properly and others don't work at all.

When I was doing master antenna work and later work for the cable companies back in the 80's I prepared cable for connectors with a Miller #101 wire stripper. Other guys prefered a sheet rock knife, there were no fancy coax strippers back then. Ring the jacket and pull it off, score the dielectric, twist and pull it off. Fold the braid back over the jacket and cut it to length with dykes. Do this about 1,000,000 times and you know exactly where to cut for every cable and connector combination you use.

Each cable and connector combination will have differing stripping dimensions and other requirements such as folding the braid back over the jacket under the connector crimp. These will be found in the connector manufacturer's literature.

I don't do nearly as much of this as I used to but I still have been using my trusty Miller stripper and dykes. I recently picked up a Harris coax stripper just to see how well it worked. Well, after spending about 20 minutes taking it apart, modifying one blade on a bench grinder so that it wouldn't cut so deep then putting it back together I finally got it so that it will produce an acceptable strip. It still needs to be adjusted with the allen wrench when I use it on different manufacturers cables. Dunno, I still can do it faster with my Millers.

Next chance I get I'm going to try a stripper from Cable Prep. I have always used their crimpers and other prep tools for solid sheathed cables (hardline). They only make tools for the CATV industry so hopefully theirs will do what it is supposed to.

My advice to you is to see what the Comcast guys use, works for them should work for you.

-Hal

 

[RRich]

Re: Quality

Just a couple of things to ponder. RG6 cable is also available with 100% copper braid. We use it for audio cable. Standard (if there is such a thing) RG6 is just that. Fairly standard with some differences by manufacturer. As stated earlier, more critical than brand or type is the termination. Proper prep is essential as well as the type of connector being used. Crimp or heaven forbid, screw on connectors are taboo! Either can create or lead to signal leakage. Invest in a good compression tool and quality fittings. You may need indoor and outdoor fittings.
The same goes for Category 5 or above UTP. Yes, a good reel in a box helps reduce kinking, but there is no substituted for two guys on the job. Again, termination is critical. Read the instructions! They come packed in every case of jacks. "Wire is wire" just doesn't ring true anymore.

 

[petersonra]

Re: Quality

Trying to make good connections with plier type tools is almost guaranteed to cause you grief. Invest the money in a proper tool. One that has a ratchet on it so that you know the crimp is made properly. same for other crimp on connections as well. Even for small rings. Use the right tool and they come out a lot more consistently.

BTW, we have been having trouble with our cable modem internet service at home. Intermittantly it fails and has to be reset. yesterday it quit altogther and would not synch back in. My wife called the cable company and they were not able to communicate with my cable modem so they scheduled a visit to come see what is wrong.

I got to thinking last night about it, and started rooting around behind my computer in the rat's nest of cables back there. I find that the cable modem tap has fallen down behind the desk and somehow in so doing the cable became doubled over. I pulled it out and straightened it up, reset the modem and it is now working fine.