Aerial for Castlebar

Gipo3

Have this aerial on house in north Sligo to recieve tv from castlebar for last 9 years.The reason for getting signal from Castlebar is due to truskmore been blocked by Benbulben. Is this aerial the correct one to have?



Now with it connected to dtt capable tv the signal is mostly ok but now and again there is pixelation and the signal qaulity seems to vary quite a bit.

Some houses in area have this aerial, but some also have aerial below and they seem to be newly installed.

Peter Rhea

What's that at the top of your aerial mast? Your own aerial would be better off up there rather than low down with the mast between the elements like that (like the top aerial in the 2nd photo).
Are you referring to the square mesh aerial in the 2nd pic?
It's some kind of microwave antenna, but what it's used for in that area, I don't know.

Gipo3

Im only on about the UHF aerials. That mesh aerial in second photo is mmds for UPC. Also cant put uhf aerial on top as thereis an mmds aerial not shown. Im specifically asking about the uhf aerials.

reaper180

the square mesh aerial is used to receive ntl channels true this mmds aerial along with a set top box provided by ntl

Gipo3

Im not asking about that.

Kristopherus

Your aerial is no good for Castlebar. You need a square similar to the UPC one on the 2nd picture. Can you pick up tv3 & tg4 with the one you have?

Gipo3

How would I need an mmds aerial for dtt from Castlebar??? Any body know the answer to my actual question?

Kristopherus

Gipo3 wrote: »

How would I need an mmds aerial for dtt from Castlebar??? Any body know the answer to my actual question?

No.You do not need an mmds aerial. And the aerial I am referring to is a similar square/rectangular one. At least that is the type of aerial used around Mayo to pick up DTT. If you can pick up TV3 & Tg 4 from the big aerial that you have, then you should also pick up the DTT from it.

Randyleprechaun

The aerial you have looks to me like it is fine for DTT from Castlebar, all though without seeing it I couldn't be 100%.

I'd be 95% sure that it is ok, it's probably wideband. Castlebar DTT is on channel 22 or479Mhz.

Perhaps it needs to be adjusted slightly or maybe some of the elements are damaged or touching something else.

ideally it should be higher up but on the other hand, if it has been working for nine years....?????.

I'd have a closer look and see that everything is tight and free from obstruction. Also check cable for damage!!!!

It doesn't have to be a rectangular aerial(grid) for DTT in Mayo, many houses in Mayo have the same as you OP

Randyleprechaun

Kristopherus wrote: »

Your aerial is no good for Castlebar. You need a square similar to the UPC one on the 2nd picture. Can you pick up tv3 & tg4 with the one you have?

Not true

Peter Rhea

Gipo3 wrote: »

Im only on about the UHF aerials. That mesh aerial in second photo is mmds for UPC. Also cant put uhf aerial on top as thereis an mmds aerial not shown. Im specifically asking about the uhf aerials.

How is the one in the 2nd pic. any different from your own, except in small details (unless you can tell from looking if it's grouped or wideband)?
What's your analogue reception like, 40+ miles from a 9KW transmitter is quite a bit, I would think.

Mayo Exile

How is your analogue reception from Castlebar on UHF channels 23, 29 and 33? Whats the quality like, good, got worse etc? As other posters have said, check cabling, connections, aerial direction and so on. Aerial also looks ok to me. Correct polarity (horizontal).

Randyleprechaun mentions that the aerial should be free from obstruction. Just wondering from your photo is the UHF aerial too near the roof/gable end maybe? The UHF aerial in the 2nd photo is above the MMDS aerial and seems well clear of any obstructions (unless there are trees/other buildings nearby). Do you get good MMDS reception? If you do, maybe the UHF aerial could be relocated above the MMDS one, and move that one lower down?

reaper180

im in ballina and receiving dtt from castlebar on this aerial
http://www.tvtrade.ie/green-group-cd-uhf-aerial.html
pointing towards nephin,, getting good signal

Gipo3

The anologue reception is grainy but I am some distance away, so this may be the reason, especially if the aerial is ok. Anyway I'll have a right good look at cables etc, also I can see about moving it higher.
But basically getting different aerial like the second photo will not make a difference?

Mayo Exile

reaper180 wrote: »

im in ballina and receiving dtt from castlebar on this aerial
http://www.tvtrade.ie/green-group-cd-uhf-aerial.html
pointing towards nephin,, getting good signal

Maybe its a UHF Group A aerial you have? http://www.tvtrade.ie/red-group-a-uhf-aerial.html

Covers channels 21 to 37. Has red plastic plugs at each end.

A group C/D aerial would have green plastic plugs. Would be the wrong aerial for C'bar (channel 22).

Peter Rhea

If your aerial is a wideband (ch.21-68) then a group A aerial (ch.21-37) should make a difference.
I for one can't tell from the photo, though.

Gipo3

It has black plastic ends?

Peter Rhea

Some makers use black bungs for wideband, others use the same colour for all models.

The Cush

If you were thinking of replacing the aerial I would recommend this one - Blake DMX10A High Gain UHF Group A aerial (CAI Benchmark Standard 1 approved).

I installed one a few years back, pulling a great signal from Mullaghanish (CH 21) in a difficult reception area. Even pulls in CH 47 DTT from Woodcock Hill side on.

Peter Rhea

OP, are you completely in the shadow of Benbulben or does it just cause ghosting on the analogue picture?
The digital signal can handle this better.

lucernarian

Wow, I don't know why there were so many posts about the MMDS aerial. Anyway, on the pole your current aerial's on, there looks to be some sort of broadband wireless receiver at the top of the pole. If that could be moved down the pole a bit and the Castlebar aerial was moved to the top of the pole then the signal would be more stable. The signal has to pass through a steel pole as it stands. Also, replacing the coax cable may yield a significant improvement if existing cable is old or if it has no foil screen (just a copper braid) etc.

The picture suggests there are two boxes which the cable passes through, when there should be one box (containing the masthead amp). Do you know what the 2nd blue box is for?

Kristopherus

Randyleprechaun wrote: »

Not true

Yes, true. Thats what I have. Also friends that are scattered as far wide as Ballinrobe, Westport, Swinford & Charlestown have the same aerial as I have.As I have previously posted, if the OP can get TV3/TG4 on his aerial at present, then he should get DTT. It may need a bit of tweeking, but, the general rule of thumb is that if the existing aerial can pick up TG4 in particular, then there's no need to change it.

Gipo3

To_be_confirmed wrote: »

Wow, I don't know why there were so many posts about the MMDS aerial. Anyway, on the pole your current aerial's on, there looks to be some sort of broadband wireless receiver at the top of the pole. If that could be moved down the pole a bit and the Castlebar aerial was moved to the top of the pole then the signal would be more stable. The signal has to pass through a steel pole as it stands. Also, replacing the coax cable may yield a significant improvement if existing cable is old or if it has no foil screen (just a copper braid) etc.

The picture suggests there are two boxes which the cable passes through, when there should be one box (containing the masthead amp). Do you know what the 2nd blue box is for?

I also dont know why there was so many posts about the mmds aerial.
I cant move the broadband aerial down any further due to trees in its line of sight.
I suspect the second blue box is for the now unused mmds aerial.
I will have a right look at cabling etc tomorrow.

Also truskmore is completely blocked as its right at foot of Benbulben, even fm radio is dodgy.

Randyleprechaun

Kristopherus wrote: »

Yes, true. Thats what I have. Also friends that are scattered as far wide as Ballinrobe, Westport, Swinford & Charlestown have the same aerial as I have.As I have previously posted, if the OP can get TV3/TG4 on his aerial at present, then he should get DTT. It may need a bit of tweeking, but, the general rule of thumb is that if the existing aerial can pick up TG4 in particular, then there's no need to change it.

Sorry mate, but it is not true true.

You stated that his aerial was no good.......not true.
You stated that he needs a grid aerial....not true. A grid aerial will work but it's not the only way. It would appear that the aerial he has, if wideband or correctly grouped is sufficient and naybe even better than a grid

Also, I think the rule of thumb is that, if you can pick up a good TV3 then you're ok for DTT, as TV3 analogue is broadcast from main transmitters as is DTT, while TG4 can be receeived from relays etc, some of which don't yet do DTT.....I'm open to correction on this!!!!!

reaper180

Mayo Exile wrote: »

Maybe its a UHF Group A aerial you have? http://www.tvtrade.ie/red-group-a-uhf-aerial.html

Covers channels 21 to 37. Has red plastic plugs at each end.

A group C/D aerial would have green plastic plugs. Would be the wrong aerial for C'bar (channel 22).

nope it is green cd aerial im using
http://www.tvtrade.ie/truskmore-transmitter.html

Galway

Kristopherus wrote: »

Your aerial is no good for Castlebar. You need a square similar to the UPC one on the 2nd picture. Can you pick up tv3 & tg4 with the one you have?

That is utter nonsense. The aerials shown is a Hirschmann FESA 817-37 -one of the best group A aerials for out of area reception and is frequently used to receive the UK analogue from Brougher Mt. or Divis from NI. Providing it has a masthead amp and is correctly aligned it should bring in DTT from Cbar. Try to 'peak' the analogue channels from there first as the DTT tends to be stronger from Cbar. A grid aerial will provide significantly worse reception as it is wideband as will all WB aerials across the group A channels. For group A transmitters, a group A aerial is by far likely to produce better results.
Also point of Info - Tv3 analogue is not transmitted from Cbar, althought it is on DTT from there.

Randyleprechaun

reaper180 wrote: »

nope it is green cd aerial im using
http://www.tvtrade.ie/truskmore-transmitter.html

That link is to details for Truskmore, which would be a C/D aerial. Castlebar would require a group A for best results

Randyleprechaun

Galway wrote: »

That is utter nonsense. The aerials shown is a Hirschmann FESA 817-37 -one of the best group A aerials for out of area reception and is frequently used to receive the UK analogue from Brougher Mt. or Divis from NI. Providing it has a masthead amp and is correctly aligned it should bring in DTT from Cbar. Try to 'peak' the analogue channels from there first as the DTT tends to be stronger from Cbar. A grid aerial will provide significantly worse reception as it is wideband as will all WB aerials across the group A channels. For any group A transmitters, a group A aerial is by far likely to produce better results.

100%

Randyleprechaun

Also point of Info - Tv3 analogue is not transmitted from Cbar, althought it is on DTT from there.[/QUOTE]


Agreed, but it's still a general rule of thumb for people that if they can receive a good TV3 analogue signal, they are good for DTT. There are of course exceptions to the rule.

reaper180

Randyleprechaun wrote: »

That link is to details for Truskmore, which would be a C/D aerial. Castlebar would require a group A for best results

when i got the aerial castlebar wasnt switched on to dtt so i pointed towars truskmore,,but when castlebar went on dtt i can pick it up at the same levels as truskmore, no difference in signal

Galway

reaper180 wrote: »

when i got the aerial castlebar wasnt switched on to dtt so i pointed towars truskmore,,but when castlebar went on dtt i can pick it up at the same levels as truskmore, no difference in signal

You would get pretty grim results on that aerial from Truskmore, group A aerials will perform very poorly in group C/d esp as high up as channels 60 and 63 for TV 3 / TG4 analogue.

You need to adjust it now for optimum reception from Cbar.

reaper180

Galway wrote: »

You would get pretty grim results on that aerial from Truskmore, group A aerials will perform very poorly in group C/d esp as high up as channels 60 and 63 for TV 3 / TG4 analogue.

You need to adjust it now for optimum reception from Cbar.

i am using a green group cd aerial for truskmore 53 and getting good results ans is also picking up dtt from castlebar on 22 with same results,, just usinf it for dtt not anologue tv,

Galway

reaper180 wrote: »

i am using a green group cd aerial for truskmore 53 and getting good results ans is also picking up dtt from castlebar on 22 with same results,, just usinf it for dtt not anologue tv,

Well if you want to improve the stability of DTT from Cbar then you will need a group A aerial facing in the correct direction. Have you tried DTT from Truskmore on channel 53?

Mike 1972

Randyleprechaun wrote: »

You stated that he needs a grid aerial....not true. A grid aerial will work but it's not the only way. It would appear that the aerial he has, if wideband or correctly grouped is sufficient and naybe even better than a grid

Grid aerials arent particularly renowned for performing well on low end channels (below the high 20's) anyway despite being:
1) Widely used for exactly that in Ireland.
2) Sold as "Wideband"

watty

Only group A aerials are good on Group A.
Wide band grid or yagi Aerials are really Group B/C . Only a Log Periodic aerial can do the entire 470MHz to 864MHz band, they can be very good if you really need all the groups. Most are not very high gain. Often a pair of grouped yagi with suitable channel combiner filter is cheaper and more gain than a large Log Periodic.

All aerials have a gradual drop in performance at higher channels, than peak channel
All aerials have quite sharp drop in performance as the channels are lower than peak channel.

lucernarian

To add to what Watty just said, Log Periodics are a fair bit weaker when it comes to the forward gain of the aerial. I've come across suggestions saying that log periodics have much better noise rejection and this allows the use of more preamplification than would be the case for an ordinary yagi. I haven't heard an exact electrical/RF reason for this increased noise rejection but I have read on the internet that the aerial must be mounted to a grounded (not with mains earth) pole for this to be effective.

The point is, 4-bay grid aerials would offer more gain than Log Periodics particularly in Group B and C/D. Log Periodics have other advantages though such as the one mentioned above (I think?!) and they have a lower wind loading and are generally less delicate for outdoor conditions.

watty

yagis have loads of side lobes picking up unwanted signals
Log periodics, if large enough, hardly have side lobes, hence better "noise" performance in some situations.

You can have same gain on Log Periodic as a Unix100. But it would be large and expensive. I don't know of anyone selling high gain log periodics.

Quad bowtie / Grid
http://www.blake-uk.com/jbb.aspx 13dBd gain (peak! most of band is less and GroupA is maybe 7dBd)

Small Log Periodic
http://www.blake-uk.com/dml.aspx 8.6dbd (probably most of band)
two of them connected via splitter would be wide band 11.6dBd and very good noise performance.

I don't think you want to earth a log periodic at all! In any case always follow the Manufacturers mounting and earthing instructions unless you are an experienced aerial designer.

Your splitter used as combiner has loss, but if followed by low noise mast preamp the loss doesn't matter as it equally attenuates any noise.

If you run the aerial cable in 2 to 3 turns of loop as tight as coax spec allows, that acts as RF choke/Balun. Do it just behind reflector.

Any combined feeds from array of aerials on same group must be same length.