Satellite or Coaxial cable

[ericmark]

For Sky TV. i.e. run from LNB to Sky box you need high quality cable as it works in the giga Hz range.

However for the UHF signal out of the sky box the quality is not so important. Much depends on length used.

The outside TV aerial should go through a de-coupling capacitor normally built into TV socket. It should not be earthed as this would encourage lighting strikes one should not try using an aerial designed for TV as a lighting conductor.

The internal TV connection will need different plates if used without a de-coupling capacitor to allow use of Digi-eye. And yes you can use more than one I have two and they work great.

You do need to select a booster splitter with DC pass for them to work.

I could not find a plate without de-coupling capacitors in fact mine even had them on Sky part of plate and I had to get soldering iron out and remove them.

 

[JustinSmith1]

For Sky TV. i.e. run from LNB to Sky box you need high quality cable as it works in the giga Hz range.

However for the UHF signal out of the sky box the quality is not so important. Much depends on length used.

The outside TV aerial should go through a de-coupling capacitor normally built into TV socket. It should not be earthed as this would encourage lighting strikes one should not try using an aerial designed for TV as a lighting conductor.

The internal TV connection will need different plates if used without a de-coupling capacitor to allow use of Digi-eye. And yes you can use more than one I have two and they work great.

You do need to select a booster splitter with DC pass for them to work.

I could not find a plate without de-coupling capacitors in fact mine even had them on Sky part of plate and I had to get soldering iron out and remove them.

Satellite quality cable should be used for all RF applications, it isn`t just about loss, see this graph (assuming some ignoramus doesn`t remove it.....) http://www.aerialsandtv.com/cableandleads.html#CableLossTable
It`s also about interference suppression, there`s research on that on the same page.

I don`t see how anyone would sell a wall plate for satellite which was isolated, something doesn`t sound right there. Just out of interest, you said you shorted out the caps, how did you do that if the plate was screened ?

 

[ericmark]

I was also surprised to find capacitor.

As to cable most my RF cable is 50 ohm and far better quality than that shown on the page you show. Also costs more.

I would of course buy best quality I could get for 75 ohm cable within reason but that does not mean I would not use cable in stock.

I am always a little uneasy buying cable which says "Low Loss" "Satellite" or "TV" cable. I consider good cable will have the DB loss at different frequencies declared. If not they have something to hide.

300 ohm ribbon best of course specially at high frequency but my wife will not let me drill the windows.

RG58 has been used for patch leads but RS components list 103 different Coaxial Cables and some cost 100's of pounds. And anyone who thinks one size fits all needs to think again.

My electric book has around 30 pages of calculations on transmittion lines and I only studied to level 5. It's a complex subject and I have found so odd things like wrong length of patch lead and cut 3 inches off and standing wave ratio is back to nearly 1 to 1.

However TV is rather low power and low quality. And in real terms 90 inch dish will do far more to improve reception than even the best coax. I can play as much as I want with my little dish and I will never get Turksat. But I don't want Turksat so in the main my little free from Sky dish is great.

And as far as original poster goes who had cable in stock I would have not told him to buy more unless something did not work.

 

[JustinSmith1]

And as far as original poster goes who had cable in stock I would have not told him to buy more unless something did not work.

I would.
I suppose it depends on ones definition of what a bodge is.
To me a bodge is doing something in one way when that way is demonstrably not the best, particularly when 20m of even the best cable is only going to cost about £10 !
Let`s get a grip here, how much would the chap happily spend on a TV ? ! ?
If using decent quality cable only prevents one glitch on his picture per day (for the next 20 years.....) it`d be well worth it.

 

[ban-all-sheds]

you can post links to a web page that shows research, but not to a site that sells stuff.

An interesting notion.

People link to the TLC site all the time, often just to show pictures of things.

If we can't do this any more then it's going to be a bit limiting.

Some clarification, and an explanation for the new rule would be appreciated.

 

[JustinSmith1]

Moderator :
you can post links to a web page that shows research, but not to a site that sells stuff.

My earlier posts linked to (original) research, so why were they removed then ? I`ve raised a query with the moderators (2 days ago) but have not heard anything yet.

 

[ban-all-sheds]

Semi-airspaced dielectric with copper braid: This cable has no foil wrap. It's commonly called 'low-loss', a designation that originated in the early days of UHF transmission to distinguish it from the smaller-diameter, solid-dielectric cables used for VHF. In fact it is "high loss" compared with type C. It usually has a brown outer sheath, though the DIY sheds stock it in white. Over the years the braid density of 'low-loss' has mysteriously decreased. In 1969 it was quite a job to unravel the braid when fitting a coaxial plug: now there's hardly anything to unravel! Some manufacturers still produce this type of cable, with braid coverage as high as 60 per cent, but these products are rarely used. Much more common are the cheap versions with braid coverage as little at 20 per cent.

No manufacturer has ever pretended that this type of cable is suitable for satellite use, but this fact is persistently ignored by builders, and by Bodgitt & Scarper Aerials and others of that ilk. What the motive is I don't know, because these cables are generally no cheaper than the C type ones.

This cable is the site electrician's favourite. Left to their own devices, this is what some of them will use for everything - UHF, satellite, surveillance cameras, dog leads, the lot. It's almost universally used for built-in downleads in new housing, where individual aerials will be fitted.

 

[JohnD]

what does the blue signify?

 

[ban-all-sheds]

It's how hyperlinks are rendered....

 

[electronicsuk]

I was also surprised to find capacitor.

As to cable most my RF cable is 50 ohm and far better quality than that shown on the page you show. Also costs more.

I would of course buy best quality I could get for 75 ohm cable within reason but that does not mean I would not use cable in stock.

Eric, I hope you're not suggesting that someone use 50 Ohm (instead of 75 Ohm) cable for terrestrial TV applications, just because they have it in stock.

 

[wingcoax]

CHECK the DATE of posting, you are a bit late,

 

[electronicsuk]

CHECK the DATE of posting, you are a bit late,

Blame Mr. Sheds!