An easy one this...
I've installed a new tv socket - it was an MK one - looks lovely but was a bit of a b***er to get the wire in. Anyway, it appears to be ok but I can't help thinking that a spare bit of braiding might be touching the centre core (it's very hard to see).
If it were so, what would the effect be - how can I tell?
TIA,
Daz
If your picture is pretty good then you have done the job.
normally you cant go wrong wiring a TV outlet the braid is folded back over the sheathing and then clamped in a brass/metal retainer.
-- Sir Benjamin Middlethwaite
Getting the braided part (already folded back) and the sheathing underneath the clamp was the hard bit - it moved the braiding around - dangerously close to the core!
I'm quite sure it's ok - if it wasn't would there be a risk of damage to my new shiny tv?
Daz
Nope, just a s**te picture!
Sparks...
| An easy one this... | | I've installed a new tv socket - it was an MK one - looks lovely but was a | bit of a b***er to get the wire in. Anyway, it appears to be ok but I can't | help thinking that a spare bit of braiding might be touching the centre core | (it's very hard to see). | | If it were so, what would the effect be - how can I tell?
You would lose signal which would be shorted out. If it works you are OK if not re-do the job.
Never having known anything much about TV aerials or the theory thereof, I was surprised once when up a ladder reattaching one to the aerial mast, to find that at the aerial end of the cable, the braid and core were each connected to different parts of the aerial; ie they are connected electrically anyway.
So that would be a 'no' to your question!
David
Yes, and no!
Electricity isn't as simple as it first looks! The two wires are connected in a DC sense, but you also need to consider AC. When the signal in a wire is alternating, the wire and anything else conducting that it passes through, will provide different "resistence" to flow. What is simply a metal loop at DC is a small coil at AC, and the higher the frequency the more significant this is. If you look at a transformer it is just a long length of wire wound into a coil - but at
50Hz it behaves very differently to at DC. When you get up to 500MHz or so that simple bent bit of metal behaves nothing like a length of wire.Ever wondered why TV aerials use coax cable? Because at UHF frequencies other sorts of cable would behave so differently than they do at DC that they would be no good.
dangerously
The MK unit in front of me has a 2 mmm gap between the centre pin and braid clamp, on that account I would make sure the braid was well under the clamp and not protruding from the pin side at all. Make sure you don't kink the cable when fitting the outlet to the wall box.
damage to my
There is no voltage on an 'ordinary' TV aerial, so no chance of damage to your set, but if one of the hairs of the braid were to touch the centre pin your picture would be made much worse, if any at all.
A satellite TV aerial does have a voltage on the centre pin and the receiver might be damaged by a hair of the braid touching the centre pin.
Roger
We-e-e-e-e-e-e-ll. They're a short at DC, anyway. The miracle of AC 'leccy, eh?
A handy tip I was told by an aerial installer is when fitting a standard aerial wall plate remove the metal clamping bits from the plate and instead connect an F plug to RF Out socket and glue that into the hole where the existing wall plate bits were. He said apart from being a much secure connection it also helps to eliminate the possibility of interference picked up on the unshielded part of the cable held by the clamp & screw
they are 75 ohms at 400Mhz though :-)
The good ones are - how about the run-of-the-mill sort though?
Really? I bet you anything that there is at least some voltage...
| > There is no voltage on an 'ordinary' TV aerial | | Really? I bet you anything that there is at least some voltage...
Two thirds of knack all, usually micro volts.
1 volt there abouts
-- Sir Benjamin Middlethwaite
You can buy screened outlets these days.
Might have that very, very, close to a high power TX, but the microvolt to millivolt region is nearer the mark.
As to the braid short, it can have varying results and possibly frequency dependent ones as well. Just make sure it isn't happening;)....
Yup - it's possible a shorted cable might improve the signal at certain frequencies...
Referenced to what?
All voltages are relative...
| Dave Fawthrop wrote: | | > On 29 Oct 2005 05:35:00 -0700, "Matt Beard" wrote: | > | > | > There is no voltage on an 'ordinary' TV aerial | > | | > | Really? I bet you anything that there is at least some voltage... | > | > Two thirds of knack all, usually micro volts. | | Referenced to what? | | All voltages are relative...
Between the core and braid of the coax.
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.