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[sheddyian]

I've got some lengths of cable that I've had for as long as I can remember - someone gave them to me, probably in the early 1980's.  Every now and then I find a use for a bit of it - as happened today - and I wonder what the cable was used for.

Then I thought some bright spark on here might know 

The cable has two twisted pairs, which themselves are twisted around each other.  One pair is white and  green, the other is black and red.  Both pairs have their own foil screen, which is blue inside but silver outside.  There is also a common bare conductor which touches the foil screens.

The cores themselves are stranded, not solid, and despite their age and less than optimum storage, are still shiny silver when stripped.

I'm just curious really, any idea what this was used for?

Ian

[oldfogy]

Looks very much like the cable a friend of mine used to use when installing CCTV equipment, the red and black was used for power and the white and  green being used for video and audio, and as you can also see, there is a twisted steel cable for strength/stainer.

[sheddyian]

ah, thanks 

I wondered if it was an early form of networking cable, but hadn't thought about CCTV.

Ian

[HPsauce]

I'm pretty sure I've used STP cable like that for wiring VDU terminals back to controllers on mainframe systems.
Can't recall the name/description though.

[sheddyian]

I'm pretty sure I've used STP cable like that for wiring VDU terminals back to controllers on mainframe systems.
Can't recall the name/description though.

Hmm, this also seems plausible!  Are you thinking of serial VDU terminals? 

Ian

[Berrick]

When I started in the computer industry back in the mid 80's we use to use this cable for visual display units using RS232 or RS422 communications.

[lloyd]

This would not have been designed for RS232. Being a non-differential standard, there is no concept of pairs; all signals are referenced to a common ground (which causes major issues).  So although you would expect an overall screen, you would not expect multiple screens as in this cable.

However RS422 is differential, and consists of two pairs, each pair screened, with a ground wire, so high possible that is what this was intended for.

No markings at all on the outer sheath?

[oldfogy]

A suggestion from my mate is that it could be, cat5e/ or cat 5 screen you can get it from mayflex
except the one in the display at Mayflex does not seem to have the wire strainer/earth, but I have not got time to search further.
http://www.mayflex.com/products/copper/category-7a/cable/excel-category-7a-screened-s-ftp-cable/

[loonylion]

no its not cat5, cat5 has 4 pairs not two, and they're thinner gauge.

[sheddyian]

It's probably way too old to be CAT5, or anything like that - this was given to me in the early 1980s, and may not even have been new then - I think one of the lengths has an identifying sleeve on it so it could have been old stuff taken out of somewhere.

I keep forgetting to have a look for markings on the cable - I've been in the shed 3 times today and each time remember once I'm back indoors.   

Ian

[HPsauce]

cat5 has 4 pairs not two

Nope. IIRC it can have any number of pairs if you study the spec carefully.
I've certainly seen (and have) 2-pair Cat5 cables.

[loonylion]

cat5 has 4 pairs not two

Nope. IIRC it can have any number of pairs if you study the spec carefully.
I've certainly seen (and have) 2-pair Cat5 cables.

Still, the gauge in the photo makes me think 'power' rather than 'signalling'

[burakkucat]

To my eyes, it looks remarkably like cable I have seen used for an RS422 interface -- as lloyd suggested earlier.

[sheddyian]

To my eyes, it looks remarkably like cable I have seen used for an RS422 interface -- as lloyd suggested earlier.

So far, given the specs etc, I tend to agree with Lloyd - RS422 does seem plausible.

I've previously wired RS232 cabling. This had - from memory - conductors of a similar thickness and stranded like this cable, just not twisted or screened.  So the chunky conductors (by modern comms standards) need not indicate power supply.

Ian

[sheddyian]

I eventually remembered to look at this cable when I was in the shed today.

Printed at regular intervals along the cable (often quite poorly) is :

ALPHA WIRE - C P/N 2466

Ian