I need to order up some more coax cable - this is for the downlead on a terrestrial aerial (currently analogue) and for feeds from a passive splitter to two TVs. May as well ensure it's futureproofed by being digital-compatible.
I know I should get CT100 grade for this(?) - ideally I would like to include it in a Screwfix order I'm compiling but could anyone tell me which of their offerings is appropriate? Presumably the el-cheapo stuff isn't; but what about H109F, PF100, RG59, "Satellite Cable", and RG6? All double-dutch to me. See list at:
Can these be simply "ranked" in order of efficiency or something (in case I have to decide between lengths/colours etc)?
In message , snipped-for-privacy@invalid.invalid wrote
The PH100 I got from Screwfix (when it was about £25/100m) is good quality foam dielectric CT100 type. The drum had all the relevant BS and CIA markings.
up from 24.95 to 40.48 once you've added VAT and delivery. With Screwfix I can always reach the free delivery breakpoint with other stuff. A roll of PF100 from Screwfix is 38.48 on that basis (and only one delivery to hang around for!)... if that's the right stuff as others seem to suggest?
Toolstation. CT100 is £23.40 per 100m including VAT and (if you buy some of the stuff you were going to get from screwfix) they also do free delivery for orders > £40.
I would disagree that these designations are all random!
RG6 and RG59 both denote cables made to specified standard dimensions by numerous manufacturers. However, used alone, to quote Bill (or misquote Macbeth!) they signify nothing!
RG6 is the standard drop cable used by cable operators (yes, I know it's underground but the terminology stems from US pole mounted distribution practice.) The centre conductor is copper plated steel (for strength as well as cost) with a bonded foil covered foam dialectric. This is surrounded by high density braid and covered in a PVC jacket. The cable is 'flooded' with a non-setting compound under the jacket. The cable is usually black.
The flooding is to help prevent water ingress if the jacket is damaged
- it forms a sticky 'seal'.
However, this cable is strong and designed for external use only - the jacket material produces toxic fumes in the presence of fire so has to be spliced to a different, safer cable before it enters a building. This cable may also be RG6 and have a similar construction except that it is not flooded and the jacket will be of a different material. This cable is usually white.
Both these cables have to meet a very high spec., in particular for screening (CATV drop cables carry signals over a very wide bandwidth -
5MHz to 750MHz (865MHz on some networks) and need to be protected from ingress from all manner of RF producing devices.)
However, a manufacturer can make RG6 cable with a single, minimal coverage screen which would be useless for such applications BUT IT WOULD STILL BE RG6!
The point of all this is that the specification of the cable is of paramount importance - terms like CT100, RG59 and RG6 only tell part the story - and price alone will not necessarily tell you which is good or bad! It's a bit like asking for 50mm screws without specifying any other parameter!
I think PF100 is CT100 with a foam dialectric, however, Bill is really your man if you want good, practical advice on what to look for!
Well you know, we used it for many years. I dread to think how many hundreds of miles of the stuff have passed through my hands, yet we aren't suffering any problems. Even very old samples seem to be holding their own quite well. The old foam-filled cables of the 60s and 70s soon developed a very bad reputation for developing excessive attenuation due to moisture ingress. We are assured (hand on heart) that the present generation of foam cables is fundamentally different, and these problems will not recurr. Only time will tell. Personally I wouldn't be too astonished if problems with these cables were to emerge in a few years.
Do you remember some of the very early attempts at making 'low loss' coax economically, such as the ones with a helix of polythene twisted around the inner, and a hollow tube to contain it? I believe some types of coax are still made that way.
Meanwhile we've just averted another fiasco. 25 rooms of a new building were about to be cabled for UHF TV using RG59. A chance remark at another job being done by the same electricians, long before they intended to involve us with the new building, led to a phone call. "Err, you are using CT100 aren't you?"
I'm hoping when I do the aerial for my friends holiday home in Ilfracombe that they cabled it up with something at least half decent. Standard low loss coax has no place in the current world of digital television.
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