Connecting a dish via pre-installed aerial co-ax

[Nozzle]

Due to the shallet style roof of my house, there is only a very tiny access point at the apex of the roof, and two easily assescible voids at the front and rear. I have a dish installed at the front with a 4 way LNB, only two ports are used at the cables are layed to the front only. There are a pair of old "analogue" aerial cables installed that go from front to rear and I'd like to think I can simply chop the old connectors off, re-fit so F-type connectors, add in some shot-gun extension pieces and voila, I can have two dish connections available to the rear of the house too.

I say this under some assumptions that I'm hoping someone can tell me I'm wrong or right.

a) Old analogue aerial cable is the same diameter as new "digital" satelite stuff, so the F-type connectors will fit.

b) Old analogue aerial cable is the same impedance as new "digital" satelite stuff, so the signal integrity is maintained.

c) Old analogue aerial cable as the same, or better, shielding than new "digital" satelite stuff, signal quality won't be any worse.

I'm not hopeful about any of these assumptions - but the alternative is to use the exisiting cables to pull new cable along the same route over the apex, and hope not to snag the insulation or Tyveck.

Nozzle

 

[Lucid]

Diameter and impedance might well be the same, though it's worth checking the diameter of the old coax just to be sure that the DIY screw on F plugs are a solid fit.

Shielding is something altogether different. New coax cable for digital/analogue use has two shields. The first is a foil (copper in the case of WF100... the recommended choice) or aluminium Mylar (basically a metalised plastic same as they use for shiny toy helium balloons) in cheaper RG6. The second is the braided wire; and again copper and a decent amount of it in WF100, or aluminium and less of it in RG6. BTW, the purpose of the shield wire is to conduct away the electrostatic charge caused by interference. which do you think is the better conductor: copper or aluminium?

If what you have is old coax with the single layer of braided copper then I wouldn't consider that sufficient shielding for LNB signals. They work at a higher frequency that Freeview digital, so shielding is more important both for blocking interference from external sources and for preventing the cable radiating its own noise.

There's nothing to stop you trying what you planned though, just so long as you know that the old aerial cable is likely to be a step down in performance compared to new.

 

[Nozzle]

A great bit of info there, thanks. I'll give it a go with the current install but I expect it won't be so good. I hope that WF100 stuff is available in reasonably short reels.

Nozzle

 

[Lucid]

A great bit of info there, thanks.

Appreciate it, but don't just say thanks, USE the THANKS button if you found the info useful. You should do that for any posts you find that are helpful whether they're addressing your question directly or if you come across something as you're reading the forum. It costs you nothing

I hope that WF100 stuff is available in reasonably short reels.

There are good retailers who sell it mail order by the metre. You can buy as much or as little as you like.

Leads pre-made for you from WF100 with the best type water resistant F plugs permanently attached: http://www.satcure.co.uk/accs/page7.htm

Cable available by the metre in both single and twin shotgun style:
http://www.satcure.co.uk/accs/WF100_cable.htm

 

[Sam Gangee]

RG6 uses aluminium foil. The aluminised mylar film type is not RG6. In fact I doubt that it has a designation other than [email protected]. But even with aluminium foil, the "RG6" type cable found in the UK usually has a steel core wire, which renders it fairly useless where it has to carry significant current (e.g. for an LNB).

So-called "low loss" TV coaxial cable has very high losses at high (i.e. LNB) frequencies. You might get away with a short length and not notice a problem. With a longer length you're likely to lose the higher frequency multiplexes - especially during rain.

So WF65 "shotgun" copper-on-copper cable is better than both of those. And WF100 is twice as good as WF65 but significantly thicker and stiffer.

OP
shallet should be chalet
assescible should be accessible