Aerial ?

Delboy5

Anyone know if its possible to buy a Televes DAT 75 aerial anywhere in Ireland ?

weehamster

I seriously doubt it that any shop in Ireland has them in stock so they would have to order it specially in for you. Shops in the North might?

Ulsterman 1690

Ive seen the odd one on rooftops in both Northern Ireland and the Republic you can get them on the CPC farnell website.

I read somewhere theyre not designed to withstand the climate (high winds) here though

Rippy

Great aerial. I have used several here in Cork and had no problems.
Is a big, heavy aerial , but it is very well constructed and if properly supported on a sturdy mast and cradle bracket & lashing kit is well up to withstanding the windload. I get mine from www.alltrade.co.uk , but they will only sell to trade.

Delboy5

I'll probably order a DAT75 from the CPC Farnell website before the year is out, do i need to get the MRD device and power supply as well ?
I'm hoping to pick up Freeview from either Brougher (30 miles away) or Divis (70 miles away) in my new house which is being built at the mo !

lawhec

Delboy5 wrote:

I'll probably order a DAT75 from the CPC Farnell website before the year is out, do i need to get the MRD device and power supply as well ?
I'm hoping to pick up Freeview from either Brougher (30 miles away) or Divis (70 miles away) in my new house which is being built at the mo !

Forget using a DAT75 to try and receive DTT from Brougher in a "fringe" area - the response pattern of the aerial is biased towards the higher UHF frequencies, something like a 6db difference from the lower end of the band to the high end. It would be fine for the likes of Limavady though.

For the likes of Brougher Mountain a Triax Unix 100 Group A is usually recommended for fringe areas. Not sure if a Group K version exists for Divis though.

Delboy5

Northern Correspondent, explain that to me in simple non-technical language !?
Is it a fact that if i get a Televes Dat75 aerial and point it at either Brougher or Divis, ill not receive any freeview channels at all ?

lawhec

Delboy5 wrote:

Northern Correspondent, explain that to me in simple non-technical language !?
Is it a fact that if i get a Televes Dat75 aerial and point it at either Brougher or Divis, ill not receive any freeview channels at all ?

Not really, the DAT75 is a "wideband" aerial that is designed to cover the whole UHF Band, it's just that it works on some frequencies better than others. The quoted gain for the DAT75 is 19db, but this only applies to some frequencies around channels 55-65. Above and below this the gain is less, where IIRC at Channel 21 the gain is about 13db, put simply at Channel 60 the aerial will collect four times the signal than it would at Channel 21. The Triax Unix 100A however is an aerial designed for Group A frequencies (Channels 21-37) where the gain is 17db with a reasonably flat gain across the frequencies it is meant to work on. Therefore to receive only Group A frequecies (which Brougher Mountain uses, 22, 25, 28 and 32 for Analogue and 23, 26, 29, 30, 33 and 34 for digital) the Triax aerial should on paper give a better performance.

Ulsterman 1690

What Northern Correspondent says about the DAT75 being better on high end channels is true for a lot of other "wideband" designs too including the ubiquitous "Grid".

Does anyone out there have any idea why Southern aerial riggers seem to love "Colour Kings" so much ? One sees the odd one up here but in the Republic they seem to be everywhere. Even in places where all the TV is on Band 4/Group A. I can understand someone using one from Limivady or Claremont Carn but not for Divis or Brougher maybe the Irish distributors have some kind of bulk discount deal with the manufacturers ????

I know one aerial rigger who used to swear by "Hirrschman's" are these the same as Unix 100's or a different one again and what are the relative merits

do i need to get the MRD device and power supply as well ?

As far as I know the MRD is just a glorified masthead amplifier (booster) ?

Rippy

Agree that DAT 75 peforms best at high end. Is true of most if not all wide-bands. One of the aerials I use is the antiference RX12. This is sold in groups,A, B, and C/D - W . So antiference reckon that there "wideband" is so close to a C/D that there is no need to produce a dedicated C/D.

AS for so many "colour-kings" being used in the south I think this is for two reasons, both to do with deflectors.
Grids have a wide angle of acceptence so if the RTE transmittr and the deflector are anything up to about 45degrees apart, it may be possible to use one aerial instead of two, regardless of group. Some guys really push this more than they should, but they tend to have 10 gallon hats and horses with ladder racks!
The other reason is that many small deflectors have frequencies all over the place, hence the need for wide bands.
Third reason, they pack well into the van, ( or the side of the horse!)
One aerial that does it all!

Hirchmanns are lovely, though pricey!

lawhec

"Colour King", "Fireguard" and "Grid" aerials are not a bad option in the C/D aerial range and are often documented (including the BBC Engineering department) as being a very good anti ghosting aerial from stray, reflected signals coming from the side or behind. There's probably more advantage to this when the receiving aerial is vertically polarised as the phasing of the four dipoles would (when the aerial is accuratly aimed at the transmitter) make the multipath signals be received out of phase. Less so for Horizontal signals. Some aerial riggers seem to swear by them.

The funny thing is that I've never seen a grouped Colour King, despite there being a good case for a Group A one. Same goes for a log periodic but at least they have a reasonably flat gain figure from 21-69.

byte

Instead of a UNIX100A, I'd agree with Rippy, and definitely consider a Hirshmann equivalent. Better aerial overall and worth the extra few quid. Antiference used to make fantastic aerials also, but I haven't seen too many in Ireland in recent times.

ColourKings are good all-round aerials, but if levels are lowish, avoid and go for the directional type.