Aerial setup in Dundalk Town.

Mayo Exile

Just moved to Dundalk and enquiring about TV reception in the the area. Most houses seem to have two aerials. The smaller ones are vertically polarised and are receiving RTE/TV3 etc. in UHF group C/D from the 250Kw mast on Clermont Carn I presume? The larger high-gain jobs are horizontally polarised are receiving BBC/ITV/CH4 in Group A. Is this signal coming direct from Divis or is it rebroadcast from a local "deflector" in the area? There is also a weak Ch. 5 signal on channel 35.

Also if you are getting BBC etc. would you need a channel filter of some sort to block out the strong signal from Clermont Carn as both aerials seem to point in roughly the same direction? Finally can you pick up DTT "Freeview" in the Dundalk town area or do you have to be nearer the border ?(Carrickarnon/Dromad area)

Ulsterman 1690

Most parts of Dundalk get their BBC's from Divis (Some can also get Ch 5 from Black Mountain on Ch 37) Id be supried if anyone's getting Ch 5 on Ch 35 due to TV3 From Three Rock being co channel

There is a UHF cable network serving part of Dundalk Im told this is because of some crane at the railway station affecting the Divis signal in Western parts of the town.

Its also possible that parts of the town can get a better signal from Camlough or even Kilkeel than Divis and in theory it should be possible to recieve TV from the UK mainland in some parts of the town as well but I dont know if anybody bothers trying.

I believe there may be a small deflector in Faughart (sp ?) Somewhere out the road to Newry but I AFaIK its coverage is pretty localised

Telefís

I live just south of the town. Don't know much about aerials, but can tell you that most of us have two horizontal aerials, and both point in the same direction - north east to Claremont Cairn and further north to Divis as described by Mayo Exile.
It seems Divis is regarded as having the best signal.

Not that 'best' isn't highly subjective; the reception is not crystal clear by any means, but is more than watchable. BBC1 is comparitively poor, but BBC2 is much better, as is CH4. UTV is usually the same as BBC1, not great, but very watchable all the same.
It used to get very bad in the summer with the heat, but this seems to have stopped in recent years...

I also live right beside the sea, and no one that I know of has tried to recieve any signals from Britain - they musn't be good enough, which is a shame considering Kippure is alive and well over there

We can't recieve DTT in the south of the town, hence we have to use the FTA satellite option. I can tell you, when we got that installed after 16 years of snowy analogue, it was more than a little shocking to see British television looking just like Irish output!
British telly always had a professional looking distant 'cinematic sheen' as a result of the light noisy haze - seeing it almost harshly crystal clear took it down a peg or two

Mayo Exile

Apologies to Ulsterman, I actually meant Ch. 37 for Channel Five. Its quite weak most of the time. To Telefis, my mates house is on the east side of Dundalk, around the Red Barns Road area and i think he gets his BBC/ITV from the 630W mast at Camlough. Its a bit snowy but seems quite stable. I'm in the centre of town and can get nothing form Camlough. Not great at geography but i'm guessing that Slieve Gullion is blocking the signal from there.

Telefís

Is Camlough in south Armagh then?
Well you mention the Red Barns Road there - I live a stone's throw from there, about a mile directly further south, so it's possible I get Camlough too but don't know! Is there anyway of checking?

Loooking at everyone's aerials around me recently, they are all positioned as expected, so that the small Irish aerial is directed ever so slightly further east to Claremont Cairn, while the larger UK one is directed a little more to the west to either Divis or Camlough.

Can NI viewers pick up RTÉ perfectly from Claremont Cairn?

Ulsterman 1690

Can NI viewers pick up RTÉ perfectly from Claremont Cairn?

Depends on where in NI one lives and how much bother and expense one is prepared to go to with aerials etc

Most places near the border can get RTE from Claremont (or Truskmore/Cairnhill/Holywell Hill/Kippure etc etc) as easily as they can get the BBC's. In Belfast signal strengths can range from excellent to non-existant depending on where in the city one is while most parts of NE Antrim East Londonderry etc havent a hope unless they are prepared to subscribe to $ky

Claremont Carn is (semi unofficially) intended for NI anyway

Is Camlough in south Armagh then?

Yeah Its pretty mountainous down there plus its a fair distance from Divis so they need a relay

would you need a channel filter of some sort to block out the strong signal from Clermont Carn

A "group combiner" should do the trick the RTE aerial goes to the group C/D input and the group A is for your BBC aerial/preamp

BTW Telefis RTE's transmissions from Claremont are most definetly VERTICALLY polorised not horizontal. If you look at the elements ("rods") on an Claremont Aerial they point up/down. Claremont (in common with many other RTE and UK transmitter sites) do radiate a small amount of power in the opposite polarity for the benefit of those living within a couple of miles of the TX site but for 99% of us this is entirely inconsequential

Telefís

Thanks for that Ulsterman - yes I know what you mean about Claremont's polarity, just I rather stupidly referred to the physical positioning if the aerials in the Dundalk area, i.e. their pointing hortizontally, rather than their polarity which is evidently vertical with their vertical rods!

It's a shame we can't get Freeview here - the country's largest town (or at least on a par with Drogheda) positioned but a couple of miles from the pick-up area

Mayo Exile

Telefis, if you are getting Divis signals the channel numbers are 31 (BBC1), 27(BBC2), 24 (ITV), 21 (CH4) and are group A horizontally polarised. If its Camlough the channels are 58 (BBC1), 64 (BBC2), 61 (ITV), 54 (CH4) and are Group C/D vertically polarised.

Telefís

Ah, well if Camlough is vertical, then we're definitely getting our signal from Divis, along with everyone else round here - thanks.

Some pics to help things along


(that one's mine - we've the tallest in the area for some reason)





And to think pictures of aerials can be atmospheric

As can be seen, all the big upper aerials are horizontally polarised for Divis while the lower small Irish aerials are pointed a teeny bit further east to Claremont Cairn.

Ulsterman 1690

The masthead amp (booster) in the second pic is swinging nicely in the breeze there. Unless someone fixes it Id say its days are numbered and I doubt if the guy with the setup on the RHS of the bottom pic is getting any BBC's at all

Telefís

(what's an RHS? )

Yes you often see connection boxes blowing about the place like those above.
Note that mine are neatly taped up

Was up there only the other week replacing the crappy developer-installed 1988 co-ax with (pricey ) copper foiled and braided cable. Very pleased with the job done, not least as standing on top of the chimney with a foot either side of the pot was necessary to reach the boxes :eek:

Are the boxes with circuit boards within boosters as you describe, or are they just connection boxes that allow the three cables to be joined together?
Does an electric current come out from the aerial input socket of the amp you plug the aerial in to in the attic to serve these boosters?

DMC

Right Hand Side.

Mayo Exile

If anybody else needs to check whether they are getting their BBC/ITV/CH4 on either Divis or Camlough and their tv tunes by actual frequencies in Mhz (like my Philips 14" portable) rather than channel numbers check out this excellent page at http://www.geocities.com/Broadway/7225/tvch.html which gives a conversion table from channel number to its equivalent frequency in Mhz.

Ulsterman 1690

Most of the aerial setups in your picture have two "boxes" on the aerial mast (pole) the first is a booster (masthead preamplifier for the technical purists) the second one (either a diplexer or group combiner) is for combining the signals from the BBC and RTE aerials in into a single downlead.

Generally the booster is the one higher up the pole and has two wires coming out (Input and output) the combiner will have three (one from the RTE aerial one from the BBC aerial/booster and one for the TV)

Setups in other areas will of course vary It is possible to get a combiner and booster all in one box but this is only usually seen in areas where the RTE's are on VHF and the BBC's on UHF

Does an electric current come out from the aerial input socket of the amp you plug the aerial in to in the attic to serve these boosters?

Yes but the "amp" in your attic (or behind the TV in some houses) probably isint an actual amp but a power supply unit -basically a transformer to reduce the supply voltage going up to the booster to a safe level (usually 12 or 15 volts) for several reasons the most obvious one being that having a full 230 volts going up to boxes on your rooftop (that rain is likely to leak into sooner or later no matter how well youve installed it) isint a particularly good idea :eek:

Using some clever electronics the Power supply combines the power going up to your amp and the signal coming down onto the same section of coaxial cable so that you dont need to run a second cable (for power) up onto your roof

Telefís

Thanks for that extensive reply Ulsterman - everyone's setup around here is as exactly as you describe!
So just to annoy you again (:)), is the booster box at the top on the horizontal aerial's cable used to amplify just this aerial's signal and not the combined signal?

The attic amp set-up is also as you outline - a transformer into which the the aerial cable is wired. The cable then emerges from this and goes into another amp box.
I'm sure these are combined nowadays, just the ones we have are nearly 20 years old now
Are both these units the same as the 2, 4 or 6 way 'boosters' you see on sale, or do these not send out the necessary current to the aerial that the transformer does?

Ulsterman 1690

is the booster box at the top on the horizontal aerial's cable used to amplify just this aerial's signal and not the combined signal?

Yes its just for the BBC aerial.

If you lived someplace where both the RTE and BBC signals were fairly weak then it would indeed be a good idea to combine the signals from the two aerials first and THEN feed them into a booster.

But in Dundalk (or most parts of it anyway) the RTE signal is much stronger than BBC and doesnt need amplification. Feeding a mix of RTE and BBC into a booster (the masthead type) would probably do more harm than good in that the strong RTE signals would overload the booster and break through on top of the weak BBC signals causing (at best) lines on the picture or (at worst) no BBC's at all

The 2 (or more) way boosters are also a form of amplifier but are designed for a different purpose namely running multiple TV's off the one aerial (Some peple try and get away with running multiple sets off the one aerial without any extra booster. With a strong signal and a bit of luck one can sometimes get away with it but usually reception does suffer). These are designed to have more moderate levels of signal gain than the masthead type but can cope better with a mix of weak and strong signals so the combination of RTE and BBC (usually) isint a problem for them.

As for "one box" solutions for combiner/masthead amp or amp/power supply There are all manner of combination boxes out there but quite frankly unless one is sure of what theyre buying it is usually better to go for seperate units. Although they may look less elegent they are (as a generall rule) more reliable and one is less likely to make mistakes when buying

Telefís

Ulsterman 1690 wrote:

it is usually better to go for seperate units.

Isn't it the same with everything

Thanks for that Ulsterman, very helpful. Just I really do need to change the distribution splitter - there's no less than six sets feeding off what is a twin-set unit :rolleyes: - all stuck in with co-ax splitters plugged into more co-ax splitters!
The transformer's fine, I'll just have to get a six-way amp...