Can you just clarify on what technical basis you think WF100 is simply an "OK quality of cable" and what you believe is better in the context of a thread about installing an aerial extension. Thanks.
How many coax cables can come off an aerial?
- Thread starter Draughtsman
- Start date
Can you just clarify on what technical basis you think WF100 is simply an "OK quality of cable" and what you believe is better in the context of a thread about installing an aerial extension. Thanks.
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I didn't deliberately demean the product. For TV aerials WH100 is perfectly good and to be honest vastly exceeds the requirements for the average domestic system.
However TV and TV networks hasn't been a significant part of my life and I've done more where a cable of that quality simply would not be in any way acceptable for various reasons. Again I'm not criticising the product, it's a case of horses for courses.
You're trying to dance around the question. Most of us here with some technical knowledge can point to cables for entirely different applications, and then say how they're not suitable for a task that they were never designed for. That doesn't have to be restricted to 'higher spec' cables either. I could tell you why the typical TV coax is unsuitable for some unbalanced audio applications. There's nothing clever in that. It's just understanding specs and applications sufficiently to match one to the other.
So, I'll ask you again, in the context of a thread about extending a TV aerial feed, what is the technical reason why you regard WF100 as merely an OK cable?
Hi Lucid.
I've seen a few of your posts and get the impression you are a competant installer, I've never seen any of your advice which I thought was wrong, maybe not the way I'd do the job but as I posted earlier there is usually more than one solution to each situation. When your advice is different to previously posted it's done in a reasoned manner, unlike some people who repeatedly jump in with both feet saying that every other bit if advice is wrong or dangerous etc and slag off/insult others in the process. If I was looking for a contractor in this environment it's fair to say you could be included on the list.
It must be obvious that most of my posting in this thread has been in response to Winston and his attitude, in this abridged quote:
He seems to imply WF100 is the best cable to use in professionally installed systems (as opposed to small domestic situations). As such my response is WF100 is OK.
I personally have worked on TV systems where the 'main' cables are significantly better products than WF100 and for that matter quite often 50Ω cable like LDF250/450/550 between head end and splitters, several reasons for this, easier to source than its 75Ω counterparts, less liable to crush damage, and usually a hell of a lot cheaper.
I'm afraid I can't add anything different to my previous:
However the very construction of WF100 makes it totally unsuitable in areas of high RF energy and sadly too many (edit: 'TV install ') contractors are unaware of that, then they start blaming every other bit of kit nearby and expect the other site users to to eradicate sources of radiation so their TV aerial (edit: system) works.
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Winston1 is a bit challenging at times 
However, in his defence, he does know his stuff. That doesn't mean I always agree with him, and he does have his hobbyhorses such as powerline adapters and the 'correct' way to fit a Belling Lee plug. (deep breaths.... deep breaths).
I try to keep my advice relevant to the enquiry in the OP, but with enough background info that (I hope) someone enquiring understands why some or other recommendation is being made. My aim is for whoever is asking to be able to go and do the job right, once, rather than taking a shortcut that ends up costing them more time and money in the long run. IME, that's the best value solution. For that reason, I wouldn't ever recommend someone splice two coax cables together. Power transfer is important. Giving away a chunk of the source signal without good reason when it costs so little to do it right just seems a mad idea. To be honest, I was a bit surprised to find anyone making the suggestion, so it got my attention. Then came the coax cable comment, but I think I can see where you're coming from on that.
Maybe you're dealing with something on the transmission side that requires greater levels of RF shielding than WF100 provides. That's okay, but I think it would have been helpful to say what the application is to give those comments some context.
Regarding professional installations; they take all forms. Everything from the big systems for hotels and large blocks of apartments right the way down to a simple-but-well-executed aerial to single TV point. All can be, and IMO should be, professional installations. As with most trades though, until there's some forced regulation, there'll always be a mix of everything from people with the equivalent of degree-level knowledge down to the bodgers who get by and cause as many problems as they solve. It was the same with plumbers, joiners, plasters, roofers, electricians; you name it. Weeding out those bodgers is a long and tedious process. The main point is though that the size of the installation doesn't dictate whether or not it is done professionally.
However, in his defence, he does know his stuff. That doesn't mean I always agree with him, and he does have his hobbyhorses such as powerline adapters and the 'correct' way to fit a Belling Lee plug. (deep breaths.... deep breaths). I try to keep my advice relevant to the enquiry in the OP, but with enough background info that (I hope) someone enquiring understands why some or other recommendation is being made. My aim is for whoever is asking to be able to go and do the job right, once, rather than taking a shortcut that ends up costing them more time and money in the long run. IME, that's the best value solution. For that reason, I wouldn't ever recommend someone splice two coax cables together. Power transfer is important. Giving away a chunk of the source signal without good reason when it costs so little to do it right just seems a mad idea. To be honest, I was a bit surprised to find anyone making the suggestion, so it got my attention. Then came the coax cable comment, but I think I can see where you're coming from on that.
Maybe you're dealing with something on the transmission side that requires greater levels of RF shielding than WF100 provides. That's okay, but I think it would have been helpful to say what the application is to give those comments some context.
Regarding professional installations; they take all forms. Everything from the big systems for hotels and large blocks of apartments right the way down to a simple-but-well-executed aerial to single TV point. All can be, and IMO should be, professional installations. As with most trades though, until there's some forced regulation, there'll always be a mix of everything from people with the equivalent of degree-level knowledge down to the bodgers who get by and cause as many problems as they solve. It was the same with plumbers, joiners, plasters, roofers, electricians; you name it. Weeding out those bodgers is a long and tedious process. The main point is though that the size of the installation doesn't dictate whether or not it is done professionally.
I agree with everything apart from the “until there’s some forced regulation” part.
I’m the third generation of electronic engineer in my family, but “forced regulation” means that I’m the first not allowed to do my own home electrics. The last thing I need is “forced regulation” to require me to get a “professional bodger” to also wire my TV aerial.
As I'm sure you know, anyone is still allowed to "do their own home electrics" in the UK, although there is a bit more potential bureaucracy involved than would have been from the earlier generations of your family.
Kind Regards, John
Again I'm comfortablewith the whole of this.Winston1 is a bit challenging at times
I try to keep my advice relevant to the enquiry in the OP, but with enough background info that (I hope) someone enquiring understands why some or other recommendation is being made. My aim is for whoever is asking to be able to go and do the job right, once, rather than taking a shortcut that ends up costing them more time and money in the long run. IME, that's the best value solution. For that reason, I wouldn't ever recommend someone splice two coax cables together. Power transfer is important. Giving away a chunk of the source signal without good reason when it costs so little to do it right just seems a mad idea. To be honest, I was a bit surprised to find anyone making the suggestion, so it got my attention. Then came the coax cable comment, but I think I can see where you're coming from on that.
Maybe you're dealing with something on the transmission side that requires greater levels of RF shielding than WF100 provides. That's okay, but I think it would have been helpful to say what the application is to give those comments some context.
Regarding professional installations; they take all forms. Everything from the big systems for hotels and large blocks of apartments right the way down to a simple-but-well-executed aerial to single TV point. All can be, and IMO should be, professional installations. As with most trades though, until there's some forced regulation, there'll always be a mix of everything from people with the equivalent of degree-level knowledge down to the bodgers who get by and cause as many problems as they solve. It was the same with plumbers, joiners, plasters, roofers, electricians; you name it. Weeding out those bodgers is a long and tedious process. The main point is though that the size of the installation doesn't dictate whether or not it is done professionally.
Power transfer is important, especially in transmitters, but to be honest this is the first of my homes to use a splitter and that is only because I needed to filter cell phone out and a 6way was available in my hire kit with filter built in, in the past it's always been cables joined in a single bunch and taped but of course there is no way I'd do that for a customer. Have you ever actually measured the loss when joining 3 cables together? I've found the cheap resistive splitter is about 2.8dB loss joining three together about 3.2dB and transformer splitter 3.4 to 4dB, hence my suggestion to OP. For that matter have you ever measured the input and output impedances of TV kit? It may come as a surprise to you.
Over the years I've done a lot of temporary work, quite often only for a few hours and 'just tacking something on' is commonplace, on one occassion we unexpectedly had to cable 32 TV's together for an event and having not brought any kit with us to do it we used twin flex for the distripution and capacitively coupled each TV onto the hot wire with a few turns of wire, turned the gain up on the modulator and it worked with no obvious problem. One of the other systems I've used in the past was a modulator with a low output impedance (I think about 4Ω) and 50Ω coax daisy chained around the system just like the old computer coax LAN system, at each TV there was simply a tee and each lead from tee to TV incorporated a 150Ω resistor.
The amount of screening in multilayer cables isn't the problem (I assume anything with a foil is 100%), it's the make up, the junctions between the different bits of copper within the screen result in diode style junctions being created which has the effect of rectifying, and hence detecting, the strong signals. the term to search for is PIM = passive intermod(ulation). It's a massive problem on multiuser sites and therefore specific types of cable are used. Sadly a lot of the RF expertise is getting lost these in days of digital signals where digital receivers are less susceptible/vulnerable.
As to the size of systems, oh yes, one of my duties included a system of potentially 4000 devices but due to the distances involved was run at VHF.
By the way, my experience of powerline adapters has been horrendous, they spray so much didital hash around that I think they should not be allowed.
Somewhere I have a Belling Lee instruction sheet on how to wire a plug.
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So you ran 50Ω cable between a 75Ω source and a 75Ω load?
Was this by measurement? Because the laws of physics would say otherwise.
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I can see this getting into transmission lines, I remember doing this in university and it gets rather complex, I think if you want to start talking about balums and matching then OK, but not on this tread, all it is going to do is confuse, yes I have mixed 50Ω 75Ω 95Ω and 300Ω cables, but to talk about that here is wrong. TV uses 75Ω cable and there is no reason why anyone with standard TV will use anything else, yes I have worked in places where some really cleaver stuff is done and as a radio ham I found this of interest, but as a normal TV user it will just confuse the guy, so if you want to talk about it start a new thread.
To @Dain1 read what @Lucid says, and forget the rest including me. She is far more down to earth, and gives good advice.
I didn't say that.
It seems that things have moved on considerably since I last looked at coax cables, b&q don't sell any coax that I recognise.
The aerial is positioned at the only end of the house that has an unimpeded view of the booster station, I need a signal downstairs at the other end.
15m should do it via a catnic that's being boxed in, then up the services/soil pipe box to the loft and out along the (black) fascia boards.
B&q do a Nexans 3 core black coax but I have no idea if it's suitable. The last time I wired one in it was brown with a copper single core and mesh outer.
Why are they 3 core?
I can deal with signal strength later, I just need a black cable installed..
The aerial is positioned at the only end of the house that has an unimpeded view of the booster station, I need a signal downstairs at the other end.
15m should do it via a catnic that's being boxed in, then up the services/soil pipe box to the loft and out along the (black) fascia boards.
B&q do a Nexans 3 core black coax but I have no idea if it's suitable. The last time I wired one in it was brown with a copper single core and mesh outer.
Why are they 3 core?
I can deal with signal strength later, I just need a black cable installed..
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