...ie, one of those pass-through wind-up reels that you can readily obtain for mains cable extensions, TV coax, phone cables - in fact pretty much any form of cable except CAT5E as far as I can see!
Does anyone know of one? I currently have an intermittently used 10m patch cable which is quite useful for various jobs, and it would be convenient j ust to be able to quickly wind it up. Why can't I find one, even from a pi key Hong Kong ebay seller? Is the cable structure just not up to it?
It does seem I'm not missing the obvious, anyway - I wonder why they are so hard to come by, compared with other types of cable reel? Must be the all-pervading prevalence of wifi these days I suppose...
I suppose so... however all empty reels that I could see during my searches seemed to be big buggers intended for mains flex; not really appropriate for what I'm after. I'll stick with what I have, I guess :( Thanks anyway! David
En el artículo , snipped-for-privacy@gmail.com escribió:
I can think of a few reasons:
putting Cat5 on a reel would make it more liable to kink as it is wound and unwound. Kinking Cat5 cable is a no-no; it can have a serious adverse impact on performance.
it would need to be stranded cable. Solid cable would (eventually) fracture. Stranded cable is only intended to be used for patch leads of short length (up to 5m ish) between e.g. the wall outlet and the device.
a partly-uncoiled reel might be more prone to picking up external interference as the loops form an antenna
Huh indeed, and I'm also having trouble excepting Mike's assertion that kinking UTP seriously affects performance. I know it's a view that's widely held, but I have never fount it to be a problem unless the conductors or their insulation are damaged.
Unlike thin net and coax in general.
After all, however well made, each termination to a patch panel or faceplate is going to effectively be a kink
plenty of evidence on Google if you can work out how to use it, including from people who know what they're talking about, like Belden, who make the cable.
Kinks cause reflections in the cable - too many and you WILL impact performance. Might work OK at 10/100 but fail at gigabit, for example.
Well, that marks you out as a cowboy installer then, doesn't it?
It's hard to tell whether you've successfully unkinked the cores because the loose outer insulation on some cables disguises problems, so although the insulation might look ok, the cores inside may not be. The only way to be sure is to use a proper tester (= $$$). If a patch cable looks ratty, the retaining clips are broken off, or it shows signs of abuse (having been kinked, walked on, run over, etc.) I bin it and replace - they're dirt cheap.
When I did building Cat5/6 flood installs of solid cable for a cable installation firm, any cable that got kinked badly during install was replaced immediately. Fluke testing them before replacement usually resulted in a failure. If the cable had only been lightly kinked and passed testing, we left it in situ.
This is why it's worth getting the pros in to do data cable installations rather than leaving it to the sparkies or so-called "IT pros".
Now that's unbecoming of you. I wanted to provoke a technical argument, not a personal one and in any case I am not involved with cable installation on a regular basis, and I have respect for those that are.
Of course you are correct about not kinking *any* cable and observing minimum radius of curvature, what I am saying is that kinks in UTP 'per se' will cause no practical ill effect to the signals, unlike coax based systems.
Clearly, kinks are the most likely areas for failure open circuit of, or short circuit between the conductors, or rupture of the sheath causing water ingress and leakage.
A friend of mine decided to make his own patch cable, thoght he did a good job but found he had far more 'collisions' then expected. The cause was tha t while he'd wired it up correctly he';d swapped teh colours over resulting in the pairs being re-twisted I think. Whenn tested he got around 3o-50% c ollisons which appeard to reduce the overall speed of the cable.
Thre's a fine line bewteen being a bit kinked and being twisted ask Jimmy s avile ;-)
You mean he made a twisted pair cable into a none twisted pair cable. It goes to show how resilient ethernet is when it still works over the wrong cables.
Its why you need to test it properly as the actual software will still work but it may not get the best out of the network.
IME you need a fairly severe kink to actually cause a problem, and the problem is usually loss of comms altogether rather than a reduction in performance.
I will make allowance since perhaps you have poor comprehension skills.
You will note that I said IME (that's "In My Experience"). Since I was describing my experience, its not something you can dismiss as "wrong" since its simply a recounting of fact.
I did not claim that a kink could not result in a performance reduction and indeed if you actually thought about it before throwing your toys out of the pram you would realise that a failure to work at all, is in fact a significant drop in performance.
Obviously if you distort the physical geometry of a twisted pair then you will introduce impedance discontinuities within the cable that will cause signal reflections. It does not take many unwanted reflections to knacker access on a CSMA/CD system, or to increase the frame error rate. Twisted pair cable is far more resilient to the effects of kinking / crushing etc than say co-ax, but its not immune.
Now this is an anecdotal sample of one, and I fully accept that its not a statistically significant sample - it may be that I just don't meet that many cables kinked in a way that causes non catastrophic performance degradation. On almost all occasions I have encountered problems resulting from cable damage, it has manifested in either failure to communicate at all, or possibly a failure to operate in the expected mode (i.e. gigabit / full duplex etc). Its possible that some of the non critical failures will go unnoticed - since not all environments will have managed switches able to report error rates, or be tested with equipment able to perform that level of analysis.
Try to stop being such a prick, and we might pay more attention to you.
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