This is CAT6A FUTP cable, overall shielded but not individually.
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Notice the twist pitch difference. The skew spec is 45 ns max per
100M, and it looks to be in that range.
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John Larkin Highland Technology, Inc
jlarkin at highlandtechnology dot com
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Doesn't the insulation look a litte fatter on the upper pair?
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John Larkin Highland Technology, Inc
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Yup. There's an x-shaped plastic thing running down the middle that keeps them a little bit apart. You can also buy CAT6A-U/FTP, which has individually shielded pairs. I think people don't vary the twist pitch on that, so the skew should be less.
I'm using CAT6A to send non-Ethernet digital data in a situation where skew matters.
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John Larkin Highland Technology, Inc
jlarkin at highlandtechnology dot com
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Precision electronic instrumentation
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VME thermocouple, LVDT, synchro acquisition and simulation
You are unaware of the twist pitch difference in CAT6 spec?
Two are twisted less than the other two.
OR two are twisted tighter than the other two.
There is a reason, and it also means they have to be terminated correctly or it doesn't work full bore.
You'll find that all the cable makers follow this spec. for CAT6.
But it being declared as UTP should mean that there is no shield at all.
We have CAT6 cable that is shielded with foil, light braid, and a drain wire, and it is most definitely not marked as UTP.
Must be if all it is is foil, it doesn't qualify as 'proper', spec compliant shielding.
It is pretty wild how there are about ten different RG-6 offerings as well, and I am not even talking about underground or carrier wire versions.
I have one that is double braid shielded and the fitting barely is able to be placed onto it. But man, it sure does scan out a lot nicer than the cheaper stuff. Both Belden wire too. Big difference.
So when they declare right there on the wire what GHz it was test at, they mean it. The 12GHz stuff is pretty damned good, and not all that much more per foot.
That is just cheap RG-6 though. We have cables that are several dollars per foot. Make all termination operations very carefully.
It is amazing how many different coaxial cable types arose from the military sector. If it were not for our boys, the entire world's economy would have been trashed 50 years ago.
That's OK. We'll let the greedy bastards on Wall Street or in Washington filch our wallets for all that is left. There will have to be some point where it becomes obvious that we are being screwed and they know it and stand there non-chalantly whistling with a smirk.
The pair twist pitch difference is deliberate in Cat6A-F/UTP, with only an overall shield. Different pairs have different twists to reduce crosstalk.
On CAT6A-U/FTP cable, the pairs are individually shielded, so they can make them all the same twist without a crosstalk penalty. The result is about 1/4 as much timing skew compared to the cable without individual shielding... numbers like 12 ns/100m as compared to 45.
My customer bought a *lot* of the wrong cables. I warned them, several times, that skew could kill this system.
--
John Larkin Highland Technology, Inc
jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro acquisition and simulation
We did see two pairs that had one prop delay, and two pairs that had a different delay. Numbers like 145, 148, 155, and 158 ns in a 30m cable.
The Hitachi that I took the pics of is marked F/UTP on the data sheet and jacket. I agree, "UTP" should mean Unshielded Twisted Pair, but it seems like it doesn't.
I once started to make a list of coaxial connectors, starting with UHF, BNC, N.... and gave up around 50 or so.
--
John Larkin Highland Technology, Inc
jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro acquisition and simulation
That is true however, that twist looks a little over twisted. our brand does not offset the twist that much. It would be interesting to see if that is consistent through out the spool/Box.
And a lot of this is vender specific as to how they construct the inners to meet the specs.
If memory serves, one of the variants my employer sells has
2 pairs twisted left hand,verses the other two right hand. I am not exactly sure the reason behind this, I think it has something to due with the cable coiling up. It may also have something to due with electrical specs in cross talk, I am sure it must have some effects on it.
I know that we have one line where I am, they oscillate the cable leads as they are being bunched just prior the extrusion. This is to keep the cable from coiling when they pull it off the real.
Yes. It has a plastic "Plus sign" shaped rib running through it. It keeps the 4 twisted pairs segregated from each other. It makes for a more uniform manufacture process, as well as a more uniform finished product. Usually nice and round shaped all along its length with few 'bumps' or perturbations.
Examining a bundle of ten or twenty short cut lengths is a good way of eyeballing the quality of the mfg processes used on each. Quality or appearance in some cases as the jacket conforms to an ugly but quite high quality signal-wise cable. Of course looking at a single piece at a time yields a lot of info too.
We must have 60 different kinds in our PN system and in stock too!
I like the Teflon jacketed, silver plated copper, shielded twisted pair, 22Ga. stuff. They are individual pairs, so four of them can be used for short (test chassis) runs without detriment.
A lot easier to terminate with mil connector contacts too.
You're like a lot of know everything and never get out, around here.
Me? I am actually employed at a place where they make the stuff and it is done on machines I was part of designing.
Yes, we have a special machine that makes a variant of that product that skews the twist offset. In the end, propagation errors in synchronous application isn't seen like it would be in the product you think you know so much about.
But in reality, any form of CAT wire is crap any ways. We also put in left and right twist lays in some of them, by customer request to help keep the cable from looping. But then again, you wouldn't know.
You are just being cheap about it. CAT wire is the last thing I would be using for anything other than ethernet. It's crap, and a fast get it the door product. Quality is not the biggest interest with that line.
The PDF is something like we use but if you can the solid strand product like this, it'll be a little faster.
Btw. You may need to spend some money.. Mouser happens to have a lot of that PN# at the moment.. And I am sure if you had a large enough order, our company could make you anything you wanted.
CAT6 cabling is perfectly reasonable for lots of non-Ethernet uses. The PCB connectors are common and standardized, you can buy connectorized cables anywhere, the combination is reliable, the connectors are nice and small.
There are 16 here:
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in a nice, compact array.
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John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com
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