coax cable for sky?
- Thread starter DIYedboy
- Start date
Sponsored Links
C
ChrisFrost
What does it say on the roll?
Sponsored Links
There is a huge amount of complete rubbish spouted about cables. If you don't have a radar station in your front garden then the cheaper stuff is more than suitable technically. The LNB brings the frequency down to a frequency which standard coax can cope with easily and the shielding is plenty good enough.
However the more expensive coax cable is hardly much more expensive so if you want to overengineer then it's not an expensive proposition to do so. This is not the case with speaker cable where you will pay an arm and a leg for cable that is no better than 2.5mm twin earth.
Yes, and you're spouting it!
'standard coax' is barely shielded. A bit of supposedly aluminium foil (it's really just silver plastic) and a braid with about 20% coverage does absolutely nothing.
If you want to get a slight understanding of RF shielding at the approximate region of the radio spectrum being discussed go look at the door of your microwave oven. There are holes in the metal shield. You don't need 100% coverage to act as an effective Faraday Cage at the frequencies being used. Go look at the satellite dish, it's got holes in it, the wavelength of the RF energy is such that it doesn't pass through these holes and bounces back.
The levels of extraneous RF in your house are so low that you don't need a thick layer of grounded copper to effectively shield the digital signals being passed down the coax. What you get in the cheaper type of coax is plenty good enough.
Make sure any connections are good and he doesn't stick a nail through the cable and the OP will be fine. If he wants to go out any buy more expensive cable then that is fine too. He just doesn't need to.
The levels of extraneous RF in your house are so low that you don't need a thick layer of grounded copper to effectively shield the digital signals being passed down the coax. What you get in the cheaper type of coax is plenty good enough.
Make sure any connections are good and he doesn't stick a nail through the cable and the OP will be fine. If he wants to go out any buy more expensive cable then that is fine too. He just doesn't need to.
Yeah, and my microwave leaks 2.4GHz radiation like a sieve, your point?
Ignoring screening for a moment, have you considered that el generico cheapo coax will very likely have quite a small conductor? Attentuation gets pretty extreme at satellite frequencies.
Actually your microwave doesn't leak like a sieve at all, unless you have somehow damaged it. In the same way cheap coax will work fine, unless you have damaged it (see my earlier post).
I also already preempted any attenuation argument in an earlier post. The LNB (B stands for Block) changes the frequency (see earlier post) and you are not getting satellite frequencies going down the coax as you claim.
And even so, you still won't have a problem with cheaper coax in a house. Cable will not be long enough, it's digital, and there isn't enough RF inside the house to interfere. That's also why you tend to put these dishes on the outside of the house, not the inside, signal at the relevant frequencies aren't very strong inside where your cable is, certainly not strong enough to interfere.
I also already preempted any attenuation argument in an earlier post. The LNB (B stands for Block) changes the frequency (see earlier post) and you are not getting satellite frequencies going down the coax as you claim.
And even so, you still won't have a problem with cheaper coax in a house. Cable will not be long enough, it's digital, and there isn't enough RF inside the house to interfere. That's also why you tend to put these dishes on the outside of the house, not the inside, signal at the relevant frequencies aren't very strong inside where your cable is, certainly not strong enough to interfere.
Walk up to any operating microwave with a 2.4GHz wireless device and watch your signal disappear when you're within a few meters. That's leaking like a sieve.
I didn't mean actual satellite frequencies, and you know it. Attentuation at 1-2GHz (which is what an LNB shifts the frequency to) is significantly higher than at around 500MHz.
Actually, even in a strong signal area, I get a lot of problems with cheap coax. Which is why I have a large roll of WF100.
C
ChrisFrost
Surely the point is that basic brown (or white) TV coax is pretty crap, and not really the thing for TV now let alone satellite.
Reasonable quality satellite grade coax (even the budgety type stuff) is better shielded and is designed to work at the frequencies uses to transmit the signal from an LNB to a set top box - And its not that expensive either. In fact, I can supply the OP with a 100M roll for less than what he spent on the cheap rubbish from Wickes even after I pay for postage. So.. we aren't talking about megabucks cable rolled on the thighs of virgins and breathed on by angels... just reasonable quality cable that doesn't cost the earth, so why mess about with anything less?
Reasonable quality satellite grade coax (even the budgety type stuff) is better shielded and is designed to work at the frequencies uses to transmit the signal from an LNB to a set top box - And its not that expensive either. In fact, I can supply the OP with a 100M roll for less than what he spent on the cheap rubbish from Wickes even after I pay for postage. So.. we aren't talking about megabucks cable rolled on the thighs of virgins and breathed on by angels... just reasonable quality cable that doesn't cost the earth, so why mess about with anything less?
You are quite right, not that much more expensive (and, I er, already said that). However, if somebody already has a reel of cable which is perfectly adequate then people should think twice before telling them to go out and spend even more of their money. Especially if their argument is flawed and shows a basic misunderstanding of the physics of RF radiation.
Thanks Monkeh and chapeau, having run the coax and plasterboarded over I then find out that sky HD needs twin coax! so I've had to go out n buy more cable (the correct stuff) and run it along a different route, hey ho
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
Sponsored Links
