Adam's wiring

[Adam]

The pairs are twisted, I take it?

I don't believe so. I've got cable from B&Q, Maplin, and a local store and none of the pairs have been twisted.

[Rik]

In which case, the noise pickup will be higher and sync will be lower.

From the Maplin website:

Telephone Cable Type CW1308

To BT specification CW1308
A high specification cable for use in wiring telephone line outlet sockets. It is also ideal for use in other low voltage, low current applications. The cable contains four solid tinned annealed copper conductors, each 0.5mm diameter, insulated with colour-coded PVC. Overall insulation is in white PVC. The 6-way is also available with black PVC insulation.

Colour-coding:
1. White - blue   2. Blue - white
3. White - orange   4. Orange - white
5. White - green   6. Green - white
Specifications:
Nom. conductor area:   02mm²
Max. working voltage:   80V
Max. current per core:   025A
Overall diameter:   4-core: 36mm

Q) Are these cables actually proper twisted pair cables (as CW1308 would demand) or do they just have parallel cores? Thanks. - Kevin
A) Yes they are.

Part number: XR66W (4 core) or XS04E (6 core).

[Adam]

I have both XR66W and XS04E and don't think that the pairs are twisted.

[Rik]

To meet the spec, they have to be, and if Maplin say they are, then they really have no excuses if they're not. The twisting is only loose, though - you'd need to gently strip 25mm of so of the outer sheath to expose it.

[Adam]

I've just cut both the 4-way and 6-way back and compared it to some Cat6 cut back, there is no way that the cable from Maplin is twisted. Trying to get them to take it back might be a challenge though.

[Rik]

It shouldn't be, Adam, they are mis-selling it if it isn't twisted.

There own website says it is:

http://www.maplin.co.uk/SEODynamicPages/module.asp?ModNo=66

ADSL Nation sell it as twisted pair:

http://www.adslnation.com/phpapps/catalog/product_info.php?products_id=96

I could find lost of people selling the stuff, but not the actual spec.

[Adam]

I also cannot find the spec, and while it may be simple in theory returning it they aren't going to want a few lengths of cut cable back. Just how twisted would it be? Cat5 and Cat6 is pretty tightly twisted, would it be the same or perhaps twisted every 5mm+?

[Rik]

It's quite a loose twist, nothing like Cat5/6. I'd say more like every 10mm on cables I've stripped.

[Adam]

I've cut in by about 50mm and the individual pairs certainly aren't twisted. But then again neither is any of the other.

[Rik]

That doesn't sound right to me, Adam. I'd have a go at taking it back - you shouldn't have to examine it to find out if the pairs are twisted, but the lack of twisting would explain the results, and that's reason enough to complain.

I'm off now - see you later...

[Adam]

That doesn't sound right to me, Adam. I'd have a go at taking it back - you shouldn't have to examine it to find out if the pairs are twisted, but the lack of twisting would explain the results, and that's reason enough to complain.

I'm off now - see you later...

Thanks again for your help, I'll give returning it a try.

[Rik]

Good luck.

[Adam]

I've found some wire that is twisted, I'm going to have to remove the new wiring and install even newer wiring.

[Rik]

Perhaps you should leave it all in place, then you can do a scientific comparison of the qualities of one batch of cable against another! 

[Adam]

The twisted pair makes the sync only be ~5000! Attenuation has also increased 2db.

[Rik]

You have something very weird going on there - I just wish I could work out what. Do you have enough Cat5 cable to try that?

[Adam]

I'm going to give the Cat6 a try just now. I've got the aluminium cable (which I do not believe to be twisted pair) connected at 7648 with a SNR of 9db and attenuation of 36db. If I have any spare I'm going to cut a long length open and check if it is indeed, very loosely, twisted.

[Rik]

By the end of this, you'll know the construction of your cables backwards.

[Adam]

By the end of this, you'll know the construction of your cables backwards.

Indeed and my telephone cabling skill levels have doubled . I can now strip the cabling and connect a socket in under 30 seconds.

The current setup is old cabling from the line box twisted together with some new cabling which is connected in the old master to a cabling leading to a socket with the router attached. It's the best I can do until the gel crimps arrive to replace the old cable between BT and me. My current sync is 6208 kbps with 37db attenuation and 6db SNR. I've achieved 6900-7300 (with about 9db SNR) on the same cabling though so I assume it must be the twisted connections causing some loss.

[Adam]

An update... I'm still waiting for some parts from eBay to complete the job, so I can't get an accurate picture of any improvements. I'm currently synced at 6208 with SNR of 1-4db, which is a small improvement over ~3700.

I've just won a 2700 router on eBay to try (I made three offers, third was accepted), so hopefully everything will come soon and I can see if any real improvement has been made.

[Rik]

That sync speed gain is more than a little worthwhile, Adam, and if your experience of the 2700 is like most of us, you'll see a further gain when that arrives.

[Adam]

That sync speed gain is more than a little worthwhile, Adam, and if your experience of the 2700 is like most of us, you'll see a further gain when that arrives.

For the cost the gain thus far has been good, imho it's been worth it providing I can keep the sync up or get better. Hopefully the 2700 will make the results even better, I'll keep you updated.

[Inactive]

I've just won a 2700 router on eBay to try (I made three offers, third was accepted), so hopefully everything will come soon and I can see if any real improvement has been made.

Care to tell us how much she finally accepted Adam, so that others may benefit, if not I will understand.

[Adam]

Care to tell us how much she finally accepted Adam, so that others may benefit, if not I will understand.

She accepted £17.50, but rejected £15. I'd limited myself to £25 (inc postage) as I knew I could get one cheaper if need be.

[Inactive]

Nice one Adam, that was the figure I had in mind, sort of keeps things tidy..