Kitz Forum
Broadband Related => Telephony Wiring + Equipment => Topic started by: hake on May 09, 2012, 07:39:04 PM
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I have a length of ADSLNation supplied Cat5e cable with two twisted pairs to be run between the NTE5 filter faceplate and the router. My question is do I use only one of the twisted pairs with the two working signal wires twisted round each other? I guess that the other twisted pair is redundant. Is that assumption correct?
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Yes, your assumption is correct. :)
You should use the two wires that comprise one twisted pair, the idea being that any stray electromagnetic field will induce an equal current simultaneously in each leg and, thus, cancel each other out.
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Thank you burakkucat. Does it matter which way I connect either wire of the selected pair to the router connector at one end and the NTE5 at the other? I think it doesn't but your confirmation would be appreciated.
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Polarity is irrelevant, so there is no need to ensure "this" goes to "that". ;)
Am I right in assuming that you intend just to extend the DSL circuit from the filter (the IDC terminals marked A & B) to an RJ11 or an RJ45 socket at the modem/router's location?
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I have a length of ADSLNation supplied Cat5e cable with two twisted pairs
Not wishing to appear pedantic, but Cat5e will have 4 twisted pairs (8 cores). So is it actually what you think it is?
What colours/banding are the cores?
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I have a length of ADSLNation supplied Cat5e cable with two twisted pairs
Not wishing to appear pedantic, but Cat5e will have 4 twisted pairs (8 cores). So is it actually what you think it is?
Good catch, HP! b*cat feels slightly :-[
I wonder if it actually is two pair CW1308 cable?
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I have a length of ADSLNation supplied Cat5e cable with two twisted pairs
Not wishing to appear pedantic, but Cat5e will have 4 twisted pairs (8 cores). So is it actually what you think it is?
What colours/banding are the cores?
Not wishing to appear even more pedantic but are you sure of that HP?
My understanding, which may be wrong, was that Cat 5e simply mandated the characteristics of the pairs, bit not the number of pairs. Since Cat 5e is pretty much the universal cable used for gigabit ethernet (in its 4-pair guise) we have come to assume it will always have 4 pairs, but I suspect that may be the Ethernet standard, rather than cat 5 or 5e.
Frustratingly I have failed to find any definitive (free) description of the ansi spec, and I'm not about to buy a copy either. However, ther do appear to be cable suppliers selling 2 core cat 5e cables...
http://www.alibaba.com/showroom/cat5e-2-pair-cable.html
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Well I've been out-pedanted. :graduate:
Lets see what the OP says, but CW1308, Cat5 or Cat5e twist spec will all be fine as long as a proper pair is used (ref B*cat)
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Well I've been out-pedanted.
Don't bank on it. After posting I noticed that if you click on any of alibaba links, to the chinese cable suppliers, the descriptions all say 8-core despite the illustrations.
I strongly suspect your suspicions were totally valid, and that all cat 5e cables, in practice, have 4 pairs. But I'd now love to know the answer as to whether a two pair cable could still claim to be cat 5e. :-\
I'd also agree that a lesser spec that 5e should be fine for dsl. Just as putting 155mph ferarri tyres on a 1972 ford escort will not make it go any faster, exceeding cable requirements for a given application is equally pointless.
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I have here a cable, supplied with a Belkin wireless router, with RJ45s on each end, and only two pairs !
Doesn't actually say CAT5 on it, but that's clearly it's intended use. What it does say on it is "Cable only to be used for wireless router" !
It's not the ADSL telephone cable, it's the ethernet patch cable.
Ian
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Doesn't actually say CAT5 on it
Darn, that would have proven something :)
Interesting nonetheless.
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According to the Wikipedia article (http://en.wikipedia.org/wiki/Category_5_cable), Cat5 and 5e cable can have as many as 100 pairs, but it doesn't make any reference to a minimum number. I don't feel up to trawling through the official specifications at the moment. :)
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:-[ :-[ :-[ :-[ :-[ This is deeply embarrassing :-[ :-[ :-[ :-[ :-[
I had a cable with two twisted pairs and, in my complete inability to understand the principle behind the use of twisted pairs, I thought I had to use both pairs whereas I now realise that one pair was surplus to requirements. It's too complicated to say what I actually did but it is an easy mistake for an oik like me to make.
I would not be surprised if others have also done something like wot I did.
Thanks to you guys for putting me back on the path of rectitude.
:blush:
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The cable supplied by ADSLnation for connection between the microfilter and the modem (with the required plugs at either end) is described as being to Cat5e standard......which is a little different to saying that the cable IS Cat5e.
I'd hazard a guess that it is foil shielded single pair twisted pair cable with the twist tightness compliant with the cat5 standard (cat 6 has has higher/closer/tighter twist) and with shielded type RJ plugs on the ends.
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I have here a cable, supplied with a Belkin wireless router, with RJ45s on each end, and only two pairs !
Yes, I have a few short router cables like that, good for 100mbps but no more. :-X
I only became aware of their existence relatively recently when I bought a gigabit switch and connected a PC close to it that I knew had a gigabit ethernet card, only to see it running at 100mbps. ???
As it worked fine with a longer standard Cat5e patch cable I investigated further and found a number in my collection - all short, oddly coloured and supplied with routers.
However, as noted above, they're not all labelled as Cat5.
Just looking at one that I think came with a BT unit it says:
"24AWG 2PAIR VERIFIED CAT. 5e TIA/EIA-568B. 2" on the cable itself. :P
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Another grey Foxconn one I have is just a "2-pair patch cable".
And another says "Cat.5" and the EIA reference as well as "2-pair".
Can't be bothered to check any more..... :lol:
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Yes, I have a few short router cables like that, good for 100mbps but no more. :-X
I only became aware of their existence relatively recently when I bought a gigabit switch and connected a PC close to it that I knew had a gigabit ethernet card, only to see it running at 100mbps. ???
As it worked fine with a longer standard Cat5e patch cable I investigated further and found a number in my collection - all short, oddly coloured and supplied with routers.
Just how much of a saving is there really to be made by the supplier/manufacturer by including a bare-minimum 2 pair patch cable with a router instead of a standard CAT5e? >:(
Likewise, as I mentioned in a different post, my modem came with an incredibly thin (28AWG) RJ11 flat cable. Replacing it with a no-nonsense but thicker (26AWG) RJ11 gave me a repeatably improved S/N margin.
Given this money scrimping on accessories, it encourages me further to try to run my modem from a 12v battery to compare the performance when running on the supplied 12v switch mode PSU that's quite noisy on an AM radio.
Ian
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Just how much of a saving is there really to be made by the supplier/manufacturer by including a bare-minimum 2 pair patch cable with a router instead of a standard CAT5e? >:(
I'd say there is actually an argument in favour of reducing the number of cores to the bare minimum, as each additional (unused) pair increases the metallic surface area that is exposed to noise pickup, and that noise can then be coupled into the other conductors, thereby increasing the noise they already carry.
Given this money scrimping on accessories, it encourages me further to try to run my modem from a 12v battery to compare the performance when running on the supplied 12v switch mode PSU that's quite noisy on an AM radio.
On a slightly related note, one thing I like about the Netgear routers (such as DG834GT) is the power brick, judged from size and weight, seems to contain a big, heavy, old fashioned transformer. In contrast, the smaller, lighter bricks that power some other routers are obviously 240V to 12V switch-mode supplies which, I always suspect, are more likely to emit unhelpful switching noise.
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If you are making millions of them then any small saving is indeed well worth it in terms of the fixed one off design/purchasing/drawings modifications effort to acquire the savings and the few pence per cable unit saved - because you are selling so many.
Additionally the smaller the overall cost of the unit the greater will be the % reduction in cost from making the change to say 'cheaper wire'. Saving 2p of the cost off a £20 router is more significant than saving the same off a £150 one.
Conversely if you work in bespoke high value equipment which will all be ones and two off's; spending a lot of time to save £5 per unit when each unit costs £million+ is not worth either the savings made or your time in devising/implementing the savings.
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. . . an easy mistake for . . .
No! (Emphatically.) Wizards do not make mistakes. They may have an inadvertent mishap. :)
Nothing further needs to be said. ;D