Warnings re: "coiled" CAT5 cords?

Den fredag den 26. december 2014 00.49.07 UTC+1 skrev Don Y:

or if you really want short,

-Lasse

Darn good reply!

Mikek

What do you intend to run through these ? 100BaseT ?

CAT5 consists of balanced twisted pairs and at higher frequencies act as transmission lines, carrying the actual data in the insulator materials between the two conductors.

Bending the cable too sharply and the balance is disrupted, allowing some information to escape and interference inserted due to the bad balance. This may also increase the crosstalk between pairs in the CAT5 cable.

Since your cable is more than 1 m long, which is nearly the full wavelength at 100 MHz (considering vf), so there can be some issues.

A general rule of thumb for coaxial cable installation is that the bending radius should be at least 5 times the cable diameter. I guess there must be similar rules in CATx installation instructions.

Yes, I saw those. I'm not concerned with finding a *source* as much as I am with learning about "issues" that I will only discover from misfortune, later!

Won't work (I have several of those -- one in each laptop bag).

I just want a cord that "passively" falls into a nice little bundle, out of the way -- yet extends (without stressing connections or its own fabrication) when needed.

Yes. I'll have a different solution when I move to Gbe.

I am assuming the folks who make these ("reputable" firms, not the "sure, I can coil this on a form for you... how long do you want it?" types) will have sorted out much of that.

I'm mainly interested in the sorts of issues that turn up after some period of *use* (wear, etc.). E.g., the actual conductors in many (hi flex) "coiled cords" do not easily lend themselves to repair. If a connector/conductor fails, you toss the cord away. If this happens often, then it's a poor solution.

OTOH, cable arms just won't work in my configuration.

One issue? Just use cat6... it is everywhere.

Big problem is that the connectors wear out, especially if the cord is too short, resulting in jerking of the connectors, which causes the plastic to fatigue and fail. The wire can also pull out if not properly clamped into the connector body.

Note that both connectors, cable side and chassis side, can fail, and replacement of the chassis side can be expensive.

Joe Gwinn

Yes, this was the reason I don't want to use the "retractable" (e.g., Lasse's second URL) cords -- they'd leave tension on the cords regardless of retracted/extended state.

I'm hoping the *coiled* option only results in the coiled cord's *weight* being the issue (so, if the mating connectors are sited "low enough", the cord itself is supported instead of relying on the connectors to support it).

Have you any first-hand experience with these? Using cable arms is just not going to be an option (and I don't want to redesign the hardware for a better solution -- yet).

Den fredag den 26. december 2014 19.20.08 UTC+1 skrev Don Y:

as far I can tell they are self locking, so they don't retract until you pull and release the right way

-Lasse

Yes, that's how the ones I have operate. But, consider: you extend the cable. Now, want to "retract it" to take up the excess slack. How do you say "stop retracting, *now*"? You *pull* on the cable, again and wait for the mechanism to "catch", again. So, you have to be able to get *at* the cable (with your hands) *or* rely on pulling from the mated connection(s).

A large number of the better brands now fully 'vacuum pot' their crimped connections with polymer after the assembly is done.

This nearly fully strain reliefs the wire connection points.

My direct experience is with coiled telephone handset cords, where I have had these connectors break from jerking (dog on short leash effect). The big problem is finding replacement female connectors to go into an old touch-tone wall phone.

Another problem I've had with ethernet jumper cables is that the anti-fishhook boots on many cables is too large to allow the cable to be plugged into many devices (which don't leave enough clear space around the socket).

Joe Gwinn

Yes, but not something one can do outside of a factory. The home brew equivalent is a well-placed drop of superglue while attaching the connector on the wire.

Joe Gwinn

I don't think this would be quite as abusive an environment. E.g., a cable arm would normally tackle the job -- just hold/guide the cables while I slide the machines out -- but I don't have room for "enough" of them (I would need a dozen in the space normally occupied by *one*).

I've a similar phone problem -- though it comes from wanting/needing a no-longer-common color for that cord (olive green).

Worst is when the latching tab adjoins a *protruding* edge of the case; need long fingernails to get at it! :<

I'm seeing that done even on cheap CCA patch cables. OTOH the patch cables Cisco provides with their VOIP phones are only crimped, no extra strain releif at all.