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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#1
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telephone cable
Hello,
I notice that a lot of "telephone extension kits" as seen in the shops, are supplied with flat cable. Does this mean the pairs are not twisted? And if so, are there any implications to this? I've just bought some own-brand telephone cable from CPC. It is the white round cable with twisted pairs inside. Following the advice on the earlier thread, I bought the 2-pair, 4-conductor cable. I notice there is a lot of space inside the white insulation. Is it supposed to be like this or is it because I bought a cheap brand? Does the manufacturer use the same outer insulation for the 3-pair and 4-pair cables and is this why there is space in my reel because these "extra" pairs are missing? Thanks. |
#2
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telephone cable
In an earlier contribution to this discussion,
Stephen wrote: Hello, I notice that a lot of "telephone extension kits" as seen in the shops, are supplied with flat cable. Does this mean the pairs are not twisted? Probably. And if so, are there any implications to this? Yes. It's *not* suitable for extensions which will have broadband kit (ADSL modem or router) at the far end. I've just bought some own-brand telephone cable from CPC. It is the white round cable with twisted pairs inside. Following the advice on the earlier thread, I bought the 2-pair, 4-conductor cable. I notice there is a lot of space inside the white insulation. Is it supposed to be like this or is it because I bought a cheap brand? Does the manufacturer use the same outer insulation for the 3-pair and 4-pair cables and is this why there is space in my reel because these "extra" pairs are missing? Thanks. Dunno. CPC stuff *should* be ok. I'm sure it will work. Is the fresh air a problem? -- Cheers, Roger ______ Email address maintained for newsgroup use only, and not regularly monitored.. Messages sent to it may not be read for several weeks. PLEASE REPLY TO NEWSGROUP! |
#3
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telephone cable
"Stephen" wrote in message ... Hello, I notice that a lot of "telephone extension kits" as seen in the shops, are supplied with flat cable. Does this mean the pairs are not twisted? And if so, are there any implications to this? I've just bought some own-brand telephone cable from CPC. It is the white round cable with twisted pairs inside. Following the advice on the earlier thread, I bought the 2-pair, 4-conductor cable. I notice there is a lot of space inside the white insulation. Is it supposed to be like this or is it because I bought a cheap brand? Does the manufacturer use the same outer insulation for the 3-pair and 4-pair cables and is this why there is space in my reel because these "extra" pairs are missing? Thanks. If the pairs aren't twisted it can upset your ADSL signal, but of course the extension kits work fine for the audio telephone service. Telephone cable isn't normally that tight in it's outer, don't know why though! Peter |
#4
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telephone cable
Stephen formulated on Wednesday :
Hello, I notice that a lot of "telephone extension kits" as seen in the shops, are supplied with flat cable. Does this mean the pairs are not twisted? And if so, are there any implications to this? They are not twisted and because of this are much more susceptible to external interference. You probably have broadband and this type of extension could well cause interference to the broadband signal, reducing your bandwidth. I've just bought some own-brand telephone cable from CPC. It is the white round cable with twisted pairs inside. Following the advice on the earlier thread, I bought the 2-pair, 4-conductor cable. I notice there is a lot of space inside the white insulation. Is it supposed to be like this or is it because I bought a cheap brand? Does the manufacturer use the same outer insulation for the 3-pair and 4-pair cables and is this why there is space in my reel because these "extra" pairs are missing? It is always like that and has always been like that. Even the several thousand pair cable used to be fairly loosely packed. -- Regards, Harry (M1BYT) (L) http://www.ukradioamateur.co.uk |
#5
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telephone cable
On Wed, 23 Sep 2009 23:03:37 +0100, Roger Mills wrote:
Yes. It's *not* suitable for extensions which will have broadband kit (ADSL modem or router) at the far end. I'd say it's not suitable for use a on a line that is used for ADSL full stop. The filter filters the POTS side not the ADLS side, if this flat, untwisted, cable is used pre filter then any interference it picks up is connected directly to the modem. Depending on the level of this interference and the common mode rejection of the modems line circuitry it could have a very bad affect on the rates the ADSL will run at. Even use post filter, on the POTS side, I wouldn't be happy about. -- Cheers Dave. |
#6
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telephone cable
In an earlier contribution to this discussion,
Dave Liquorice wrote: On Wed, 23 Sep 2009 23:03:37 +0100, Roger Mills wrote: Yes. It's *not* suitable for extensions which will have broadband kit (ADSL modem or router) at the far end. I'd say it's not suitable for use a on a line that is used for ADSL full stop. The filter filters the POTS side not the ADLS side, if this flat, untwisted, cable is used pre filter then any interference it picks up is connected directly to the modem. Depending on the level of this interference and the common mode rejection of the modems line circuitry it could have a very bad affect on the rates the ADSL will run at. Even use post filter, on the POTS side, I wouldn't be happy about. Fair comment. To summarise, lets says that it's ok for extending an analog-only setup, but best avoided *anywhere* in a setup which uses ADSL broadband. -- Cheers, Roger ______ Email address maintained for newsgroup use only, and not regularly monitored.. Messages sent to it may not be read for several weeks. PLEASE REPLY TO NEWSGROUP! |
#7
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telephone cable
In article ,
Harry Bloomfield writes: Stephen formulated on Wednesday : I've just bought some own-brand telephone cable from CPC. It is the white round cable with twisted pairs inside. Following the advice on the earlier thread, I bought the 2-pair, 4-conductor cable. I notice there is a lot of space inside the white insulation. Is it supposed to be like this or is it because I bought a cheap brand? Does the manufacturer use the same outer insulation for the 3-pair and 4-pair cables and is this why there is space in my reel because these "extra" pairs are missing? It is always like that and has always been like that. Even the several thousand pair cable used to be fairly loosely packed. If packed tight, it would end up with the twists concentrating themselves into kinks, with untwisted lengths between the kinks, and also adjacent pairs locking twists against each other (each pair should have different number of twists per metre to stop that from happening over a long cable run). Phone cable only needs a very few twists per metre in theory, but is almost always made with very much more because it's easier to make sure you don't end up with parallel runs where the twists ran off into little clumps. If you go back to hundreds of pair paper spaced cables where that's not an issue, they're something like 1.5 or 2.5 twists per metre (I can't recall the exact figure). -- Andrew Gabriel [email address is not usable -- followup in the newsgroup] |
#8
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telephone cable
Phone cable only needs a very few twists per metre in theory, but is almost always made with very much more because it's easier to make sure you don't end up with parallel runs where the twists ran off into little clumps. If you go back to hundreds of pair paper spaced cables where that's not an issue, they're something like 1.5 or 2.5 twists per metre (I can't recall the exact figure). Phone cable was two and a half turns per foot AFAICR. We didn't have metres in those days :-) -- John W |
#9
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telephone cable
"John Rumm" wrote in message ... Stephen wrote: Don't think so - there is a similar space in the 3 pair version. It allows the cable to be abused on corners and otherwise flattened a little in places. I would think a cable with a large number of small diameter individual conductors would have to be loosely packed, or the conductors on the outside of a bend would be severely stressed. Bill |
#10
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telephone cable
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