That is, the cable from the back of the TV to the wall plate.
I need to watch the TV in the annexe which has no wall plate, so I could run an extension from, say, the kitchen's wall plate. But what is the limit to the length and would I need some sort of booster?
The aerial is currently driving a 14"analogue (CRT) Sony portable, but will soon be connected to an LCD TV.
MM
In article , MM writes
Provided you have a reasonable analogue picture in the kitchen I'd expect an extension of at least 10m to be a walk in the park and 20m may well be fine. If your LCD telly is digital then you may find that a cheap fly lead (extension) will let in electrical interference resulting in occasional picture breakup. If this is the case then a better, double screened lead should fix it but it may have to be made up by an aerial shop for you, asking for CT100 cable if that is the route you take.
Thanks, Fred. The electrical shop in the town near me has two 10m cables, a cheap one (£4) and a better quality one for HD (£6.99). But anyway I was too late to get there this afternoon, being a Saturday.
MM
In article , MM scribeth thus
Depends on what the signal level is like at the wallplate. If a decent level already then it may well be fine over some 10's of feet if your in a not that good area to start with then perhaps not.
Best if to try it and see amplifier less, ands if it goes noisy add an amp but at the driving end of the cable else you'll -amplify- the losses too;!..
Do use a decent double screened cable such as CT100 or similar..
This is alas one of those "how long is a piece of string" questions. It depends on how much signal you have and what quality it is. How much your TV needs. And what quality of cable you are using to extend it.
All of which are unknowns.
So without any test equipment, the best you can do is try it and see. Assuming the picture is good now, then dropping in another 15m of decent quality foil screened co-ax is unlikely to degrade it much. If you wanted 50m then that will make more difference.
And the LCD with probably have a digital tuner, which will open another can of worms depending on the local reception conditions for digital channels.
You would probably be better going to somewhere like Maplin, and getting them to cut you a length of CT100 (or similar quality) co-ax, and sticking a plug on either end. Many of the pre-made TV fly leads are poor to say the least.
In message , tony sayer wrote
Background info
Guide price for a decent quality cable is around 40/70p metre for short lengths. Example
gets a bit crap after 50 meters of sat grade coax
If you have a few minutes to spare, there is another question:
My house is equipped with a Philex SLx6 aerial amplifier in the loft. This has 6 output sockets, of which only five are connected at present (kitchen, bedroom 1, bedroom 2, bedroom 3, and living room).
Reception is excellent in four rooms, but in the living room the picture was grainy. Not too bad, but definitely not as good as in any of the other rooms, all supplied with the same type of wall outlet.
I have just spent an hour up in the loft tracing the cables from the amplifier to the various rooms in order to isolate the one going to the living room and causing the grainy picture. In the process of this tracing I pulled the cable out from under the loft insulation as I tracked along it so that I could expose the whole cable and check for "funnies", like someone may have hit it with a chisel or something.
Then I connected my little portable once more to the living room wall outlet, went back up into the loft and reconnected the suspect cable to the amplifier.... Result: Perfect reception!
But why? What gives here? (I am no electrician, although I understand the basics.) The cable is at present simply laying across the loft, on top of the insulation (rock wool, not that that makes any difference).
In a nutshell: Cable routed "neatly" alongside joists under insulation = poor reception Cable simply laid across the loft on top - good reception
This cable is very long. From the aerial amplifier to the wall outlet downstairs it must be 15 metres, perhaps even 17.
I was expecting to have to pull the cable out of the conduit and possibly replace it, but that now seems superfluous, since I don't care if the cable simply lays there where it now is.
Any comments (from anyone) most welcome.
Thanks!
MM
I would hazard a guess that the likeliest cause is a poor connection in the plug that's that's going to the amp. I'd take it apart and make sure that the screen isn't shorting with the central conductor.
Tim
I don't see how it can be that, since I haven't disturbed the amplifier end of the cable hardly at all. There is about a metre of loose cable where it connects to the amplifier and I had already unpluged then re-plugged the cable into the amp, trying differing output sockets on the amp. But all the while the cable was routed the way it was originally (along the joists, turned a right-angle, beneath the eaves across to the outside wall, then into the conduit), reception was grainy; "un-routed" the cable and simply laid it flat across the insulation, good reception!
MM
It sounds like you either had a loose connection somewhere, and just moving it has fixed that. Of possibly you had some physical stress on the cable (kink, crush, fold etc) that was impairing its performance, and moving it has released that.
To be honest even 20m is not particularly long...
Well, indeed, the cable *was* kinked somewhat at the point it turned a right-angle, then lay along (parallel to) the eaves. That is, the cable was laid loose (resting on the plasterboard of the ceiling beneath) until the right-angle, and at that point the installer had secured the cable with a cable clip, then turned it through 90 deg to go under the eaves. However, if that was an electrical cable it would not affect anything, so is an aerial cable different (more susceptible) in this respect? Of course, I am well pleased with my stint in the loft this afternoon, 'cos I had visions of chasing a new cable route down the wall, since the cable appears to be a tight as a duck's arse inside the conduit down to the living room.
MM
Use the right cable type
NT
In message , MM wrote
Yes. Google for "aerial cable crushing". The bend radius of a coaxial cable should be no less than 10x the diameter of the cable. The cable should not be crushed. A foam dielectric can held prevent (not eliminate) crushing.
In article , MM wrote: } There is about a metre of }loose cable where it connects to the amplifier and I had already }unpluged then re-plugged the cable into the amp, trying differing }output sockets on the amp. But all the while the cable was routed the }way it was originally (along the joists, turned a right-angle, beneath }the eaves across to the outside wall, then into the conduit), }reception was grainy; "un-routed" the cable and simply laid it flat }across the insulation, good reception!
I expect this is co-axial cable with a solid copper central conductor. Probably that has broken somewhere internally and by moving it you have put it into a position where the ends of the break are now being pushed against each other. The most likely place for such a break is where it was turned too sharply in a bend. It may be ok now, or heating and cooling may make the join fail again. If so, since the fault is obviously somewhere in the section you disturbed, you can just replace that bit.
In message , Tim writes
Another favourite problem is pin of the plug, assuming a Belling Lee plug rather than an F. Quite often for speed the installer will not solder the coax inner to the pin of the plug, maybe he will have crudely crimped it with a pair of side cutters, most likely not though. This can lead to problems years down the line with corrosion isolating the coax inner from the pin. Any slight movement could have remade the connection. Although the pin and inner may not have been making contact there could have been enough capacitance for a signal to get across, but not strong enough to give a good picture.
Very much so. With power, as long as the two wires are kept apart and insulated from each other and the surroundings, then a cable will carry on doing its job. With radio (i.e. TV) frequency signals the behaviour of cables gets significantly more complex, and the design and geometry of the cable has a big effect on how well it carries the (massively more delicate than mains power) signal. Deform the spacing between the centre conductor and the screen of the co-ax and it can significantly alter the amount it attenuates the signal passing through it.
Well it sounds like you have escaped that for the mo, although with the switch to digital you may not be out of the woods yet ;-)
I never solder those things, and I expect the tiniest amount of capacitance will do the job. Actually, I often only have to hold the plug near the RF socket on a TV, and I start to get a picture, on an analogue set at least.
(In fact, I'm just done a test on a digital TV, disconnecting the RF lead at a joint: if the outer screen is in contact, I start to get a picture when the inner core is 2 or 3 mm away from the centre pin! So the signal can jump an air gap of a tenth of an inch, and from one point to another, while an unsoldered wire will have a 1 or 2cm length in a hollow tube so a greater capacitive effect)
In message , BartC wrote
But if the coax is also being used to supply power to an amplifier (unlikely in the case of the OP) the dc voltage will not jump the 2 or
3mm gap.HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.