Aerial Splitting

coolkid28 · 15 Mar 2012

Hi All,

I have a New External Aerial, i want to split it (in the loft) to 5 rooms, I've been advised that it's best to amplify the signal, as if your using all 5 TV's at once then you would put a signifcant strain on the signal. I found just your basic 5 way splitters that cost around £4, but can anyone confirm if i should be using a amplifyer, and can anyone reccomend a good quality, affordable Amplifyer

Can anyone reccomend a Good Online Company to Order From ?

Thanks in Advance,

Tom

Sam Gangee · 15 Mar 2012

It's likely that you'll need a masthead amplifier. Sending less than a fifth of the aerial signal to each TV may be as tad optimistic unless your signal is strong. Check the "Wolfbane" predictor to see how strong it is.

http://www.wolfbane.com/cgi-bin/tvd.exe?

More info: http://www.satcure.co.uk/tech/amps.htm

coolkid28 said:
Can anyone reccomend a Good Online Company to Order From ?

Depends how you interpret "good". Do you want cheap & cheerful with no technical support or extremely knowledgeable with good technical support and slightly dearer?

coolkid28 · 15 Mar 2012

Sam Gangee said:
It's likely that you'll need a masthead amplifier. Sending less than a fifth of the aerial signal to each TV may be as tad optimistic unless your signal is strong. Check the "Wolfbane" predictor to see how strong it is.

http://www.wolfbane.com/cgi-bin/tvd.exe?

More info: http://www.satcure.co.uk/tech/amps.htm

coolkid28 said:

Can anyone reccomend a Good Online Company to Order From ?

Click to expand...

Depends how you interpret "good". Do you want cheap & cheerful with no technical support or extremely knowledgeable with good technical support and slightly dearer?

"extremely knowledgeable with good technical support and slightly dearer?" please.

nickp34 · 17 Mar 2012

This will do the job: http://www.tvlink.co.uk/t-series-amplifiers.htm

If you wanted to distribute more than just the antenna the Loftbox would be better. http://www.tvlink.co.uk/loftbox.htm

Sam Gangee · 17 Mar 2012

nickp34 said:
This will do the job:

No it won't. It's not a masthead amplifier, it's a distribution amplifier with low frequency/DC bypass for a Sky magic eye. This question is about Freeview.

I'd use a low-noise masthead amplifier to feed your passive splitter.

Sam Gangee · 17 Mar 2012

coolkid28 said:
"extremely knowledgeable with good technical support and slightly dearer?" please.

OK, try these:
http://www.satcure.co.uk/
http://www.aerialsandtv.com/

There may be more but those are the only two I can think of with good technical support.

nickp34 · 17 Mar 2012

You dont have to use a masthead amp. Our aerial goes direct into an 8 way loftbox and freeview is fine on all the 5 tvs.

Sam Gangee · 18 Mar 2012

And some cars run happily on remould tyres without balancing.

The signal at an aerial can be weak and, if it is, you must use a low-noise amplifier so that you don't add any more noise than necessary to the already-weak signal, otherwise you risk intermittent picture loss. Typical noise figure for a decent masthead amp is 1.5dB.

In contrast, a distribution amplifier is expecting a signal direct from equipment and the best (claimed) noise figure I've come across was 3dB. If you are tempted to think "that's only twice as much", think again, because it's a logarithmic scale, not linear. It's much worse than "only twice".

So there's a difference between what you can "get away with" in one situation and what you ought to be using. I see no point in taking the risk.

The other (sometimes) advantage of a masthead amplifier is that it draws its power through the coaxial cable. Consequently, you can put the Power Supply Unit anywhere along the length of the cable. It doesn't have to be in the loft (where few people have a power socket). The only possible disadvantage is that you must ensure that any sockets and splitter connected in the line are "DC pass" variety. This is not really a "disadvantage" but merely an inconvenience if you need to change an existing wall plate or splitter.

BTW a "Loft Box", if you really mean "Loft Box", has a built-in masthead amplifier. But I suspect you mean a "distribution amplifier" (like the one you've linked to) because the purpose of a true "Loft Box" is to combine aerial signal with satellite LNB signal.

coolkid28 · 18 Mar 2012

Sam Gangee said:
And some cars run happily on remould tyres without balancing.

The signal at an aerial can be weak and, if it is, you must use a low-noise amplifier so that you don't add any more noise than necessary to the already-weak signal, otherwise you risk intermittent picture loss. Typical noise figure for a decent masthead amp is 1.5dB.

In contrast, a distribution amplifier is expecting a signal direct from equipment and the best (claimed) noise figure I've come across was 3dB. If you are tempted to think "that's only twice as much", think again, because it's a logarithmic scale, not linear. It's much worse than "only twice".

So there's a difference between what you can "get away with" in one situation and what you ought to be using. I see no point in taking the risk.

The other (sometimes) advantage of a masthead amplifier is that it draws its power through the coaxial cable. Consequently, you can put the Power Supply Unit anywhere along the length of the cable. It doesn't have to be in the loft (where few people have a power socket). The only possible disadvantage is that you must ensure that any sockets and splitter connected in the line are "DC pass" variety. This is not really a "disadvantage" but merely an inconvenience if you need to change an existing wall plate or splitter.

BTW a "Loft Box", if you really mean "Loft Box", has a built-in masthead amplifier. But I suspect you mean a "distribution amplifier" (like the one you've linked to) because the purpose of a true "Loft Box" is to combine aerial signal with satellite LNB signal.

Thanks for the Advice, so by reading you comments you don't reccomend a Distribution Amplifier, but either a Masthead Amplifier or a Loftbox would do the trick,

Would either of theese be sufficent:

http://www.satelliteandaerialsuppli...way-masthead-100ma-power-supply-sold-as-a-kit

http://www.satelliteandaerialsupplies.com/product/?s=labgear-hdu-681s-8-way-home-distribution-unit

Also i would need to install the masthead amplifier about 3 - 4 meters away from the arieal.........is the ok ?

Could you post more info on DC Pass please ?

Thanks,

plugwash · 18 Mar 2012

Sam Gangee said:
In contrast, a distribution amplifier is expecting a signal direct from equipment and the best (claimed) noise figure I've come across was 3dB. If you are tempted to think "that's only twice as much", think again, because it's a logarithmic scale, not linear. It's much worse than "only twice".

Actually a difference of 1.5db means about 1.5 times as much power or about 1.2 times as much voltage which isn't that much in the grand scheme of things.

IMO the only times a masthead amplifier should be needed are either in areas with extremely poor signal (where you are trying to eek out every last drop of performance) or where the aerial itself is inadequate.

Sam Gangee · 18 Mar 2012

coolkid28 said:
Would either of theese be sufficent

Wolseley is a good make but that one has only 4 outputs so you'd have to split one output to feed the two shortest cables, in order to get 5 outputs.

Also, to see whether you've chosen a "cheap & cheerful with no technical support" supplier, why not email the question to them to test the response?

Sam Gangee · 18 Mar 2012

plugwash said:
Actually a difference of 1.5db means about 1.5 times as much power or about 1.2 times as much voltage which isn't that much in the grand scheme of things.

Maths isn't my strong point so please express 1.5dB of noise and 3dB of noise as a percentage of the original signal. In other words, exactly how much noise is being added?

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Aerial Splitting

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