TV RECEPTION, CROSS, Co. MAYO

firemansam1

Can anyone advise me as to what transmitter is best for receiving DTT from Cross Village in Co. Mayo.

Thanks

Randyleprechaun

Not too familiar with the area but I'd guess Castlebar!!!!

I'm sure someone else on here will be able to tell you for sure

Kristopherus

As you are on the very south of the county, you should try Maghera or Tonabrocky outside Galway city. The Partry mountains are likely to block the signal from Castlebar. Best bet is to make sure you have the correct arial and turn it towards the North for Castlebar and then South or Southeast for Tonabrocky and Maghera. You will be very unlucky not to get a good signal from at least one of them.

firemansam1

Kristopherus wrote: »

As you are on the very south of the county, you should try Maghera or Tonabrocky outside Galway city. The Partry mountains are likely to block the signal from Castlebar. Best bet is to make sure you have the correct arial and turn it towards the North for Castlebar and then South or Southeast for Tonabrocky and Maghera. You will be very unlucky not to get a good signal from at least one of them.

So, I'll need to get a wideband aerial so as maghera would be different band to Castlebar and tonabrucky. Am i right

Kristopherus

I'm not an expert on the various aerials, I'm afraid. Just mighty thankful that the aerial I have for the deflector system also picks up Saorview:). Have a look at the stickies. They do list the various types for the different masts.

Sponge Bob

seeing as castlebar is received in Oughterard thru a gap in the hills around Cong ....and as far south as Claregalway...I would try a Castlebar aerial, group A I think...see Wattys and Slegs saortv in my sig

Galway

Sponge Bob wrote: »

seeing as castlebar is received in Oughterard thru a gap in the hills around Cong ....and as far south as Claregalway...I would try a Castlebar aerial, group A I think...see Wattys and Slegs saortv in my sig

Castlebar is your best bet BUT you are better off to use a a group A aerial as the DTT is on channel 22. Maghera (Clare) on Channel 48 is definitely a possibility as Maghera analogue is received in Cong. Also you may wish to try Truskmore (Sligo) on channel 53 as this gets into Ballinrobe. You will need a group C/D aerial for Maghera or Truskmore.

Forget Tonabrucky it is far lower power and is only a fill in for Galway City, though I can receive it from 8 miles south of Tuam, mind you I have LOS to the mast there. The DTT from there is on channel 26 and the polarisation is vertical, all the others are horizontal incl. Cbar. Castlebar analogue is received all the way along the Tuam Road to Two Mile Ditch and Castlegar where Maghera is poor due to hilll at Ballybrit.

snaps

Castlebar (22) is very strong on DTT. You most possibly already have an aerial pointing to Castlebar??

I can Truskmore (53) and Maghera (48) as well, very strong signals here.

I also get a weak signal on 42 i think it is.

firemansam1

Thanks snaps,

What kind of aerial/setup would you recommend, it's a two storey house near the village?

Would in the attic work do you reckon?

Thanks

MBSnr

firemansam1 - I'm just up the road from you towards Cong and I have an aerial pointing towards Maghera in the attic getting 88% signal quality.

firemansam1

MBSnr,

What kind of set up have you ie. what kind of aerial and are you using masthead amp

Thanks

MBSnr

No masthead amp. Have a MVision HD300 connected to this!!! No laughing!.

Made it just because I had the bits lying about and thought if it doesn't work I'll buy the proper aerial instead. ( Used 2m of cable [instead of the wire between the connectors] and one of these balun connectors). I was amazed it worked but it does!

firemansam1

So I'd say a Triax 18 Supergain would do the trick so!!!!

Sam Russell

MBSnr wrote: »

No masthead amp. Have a MVision HD300 connected to this!!! No laughing!.

Made it just because I had the bits lying about and thought if it doesn't work I'll buy the proper aerial instead. ( Used 2m of cable [instead of the wire between the connectors] and one of these balun connectors). I was amazed it worked but it does!

That balun you used is for FM and probably does nothing at UHF frequencies. The balun is a transformer converting the balanced signal from the aerial to anunbalanced signal, where one side is earthed. Because of the high frequencies involved, baluns at the UHF range are tuned and require a quarter-wave elements to work. If you omit it, you might lose 3dB or more of the signal, but if you put in an inappropriate balun, you will lose 3dB or more of your signal.

I would try it without, as it will work just as well, and be that much cheaper.

By the way, that is quite a good design. A simpler version might be just as good though as the signal is quite robust.

MBSnr

Sam you could be right - I don't know enough about that. The balun was just a handy way of taking the bare 300 ohm cable ends and connecting them to the 75ohm coax cable. The balun said 300 -> 75 and the numbers matched...

Works though - never anything less than 80% quality.

snaps

firemansam1 wrote: »

Thanks snaps,

What kind of aerial/setup would you recommend, it's a two storey house near the village?

Would in the attic work do you reckon?

Thanks

Any wideband UHF aerial will be ok, A grid for the chimney or a standard 12 element wideband yaggi in the attic. I can get DTT from Castlebar on an indoor uhf aerial (mini yaggi type, not rabbits ears) here in Ballinrobe (Upstairs only).

You'll possibly need a masthead UHF amp and a power supply, but like i said with the DTT, you may not need amplification as its fairly strong compared to analogue.

I would reccomend a wideband UHF, just incase you change transmitters or a different mux comes on board and you wont need a 2nd UHF aerial then.

In most spots we are fitting aerials, we are finding attic mounts are more than doing the job in hand. Castlebar DTT has a real spread, even as far out as Achill.

I think cross is in a dip? HAve a look at neighbouring houses to see what way their aerials are pointing. That way then you'll know if your going for Castlebar or Maghera.

lucernarian

A grid doesn't have much better gain than a contract wideband yagi and has higher wind loading. Wouldn't it make more sense to use a grid in the attic or a wideband yagi on the chimney?

MBSnr

snaps wrote: »

I think cross is in a dip? HAve a look at neighbouring houses to see what way their aerials are pointing. That way then you'll know if your going for Castlebar or Maghera.

I think a lot of houses are pointing towards the Castlebar/Ballinrobe direction for the relay.

You're right - the main bit of the village is a bit lower down than the surrounding area. Being towards Cong means I have Lough Corrib in front of me giving 19 miles of flat to Galway. That may make a difference to the signal I get on my foil wrapped cardboard coat hanger aerial!

lucernarian

MBSnr wrote:

...foil wrapped...

Foil wrapped anything in radio reception tends to be a bad thing! Foil being good at blocking radio waves. Is it something like this? http://uhfhdtvantenna.blogspot.com/

The one in the link is fine, it's a homemade grid aerial effectively.

MBSnr

yes....see my earlier post...

lucernarian

MBSnr wrote: »

yes....see my earlier post...

Ah, sorry about that. I skipped over all of it as the last time i checked the thread was when there was only 5 or so posts and I was only following the OP's issue.

When looking into making my own aerial, the balun was the hardest thing to find info on. The special transformers were hard to find and many articles simply went over my head even though I've soldered electronic circuits in my time.

I tried adding a coaxial half-wave balun to a contract aerial once, and I noticed a very slight improvement in analogue picture quality. Made no difference to a VHF aerial. http://n-lemma.com/calcs/dipole/balun.htm

Sorry for going off topic!

watty

one trick is simply to coil about 3 to 4 turns of the coax as tight as possible without kinking or damaging the coax or foil close to the aerial. This acts as a UHF RF common mode "choke" which achieves almost the same as a Balun.

snaps

To_be_confirmed wrote: »

A grid doesn't have much better gain than a contract wideband yagi and has higher wind loading. Wouldn't it make more sense to use a grid in the attic or a wideband yagi on the chimney?

Ive found that grids are not great at all in the attic and common contract yagi's perform better in attics.

Grids really are only good for multiple transmitter reception like around here in Ballinrobe as we recieve Castlebar, Truskmore, Balla (Deflector). Grids reduce the amount of ghosting on poorly aligned or multiple transmitter reception.

watty

A grid/Bowtie does 7.5dBd (cheap) to 10.8dBd (best Model) gain across band. May peak near 12dBd on one Channel.
[Edit: OK I forgot about reflector on my post originally]

A smallest 7 Element Contract Yagi maybe 7dBd to 8dBd Gain

SR series 13 Element yagi about 10dBd to 11dBd

SR series 18 Element about 12.5dBd to 15dBd depending on model and Channel.
http://www.blake-uk.com/sr.aspx
This is the most robust and "proper" yagi. The spiky ones are "Fashion"
http://www.blake-uk.com/dmx.aspx
(Argos, Maplin, B&Q etc less sturdy X styles equivalent would be about 64 to 75 element.

A "100 Element" Yagi is usually really 21 to 25 elements and about 15dBd
JBX21 S&C A-B-CD-W 104 "elements" 14.5-15 dBd (21 bays)
Much less robust (Unix100, Triax, Kathrien DX aerials) http://www.blake-uk.com/jbx.aspx

Having 4 yagis is same principle as 4 x bowties on a Grid (dipoles).

Each time you double the number of aerials, the gain is +3dB more.
Now the coupling to match pair to coax loses signal, but it attenuates the noise too, so a low noise mast amp just after the coupler is best.

The SR series are not "fashionable" but they are best Yagi money buys. Very robust and best gain for you money.

SR10 basic reception if Grid isn't enough = 9dBd to 11dBd depending on Channel
SR13 medium gain. 11dBd to 13dBd approx (varies according to channel)
SR18 high gain 12.5dBd to 15dBd depending on channel

DX
2 x SR18 coupled = 15dB to 18dBd equivalent (assuming very low noise mast amp to cancel loss of combiner).

4 x SR18 coupled = 18dBd to 21dBd equivalent (assuming very low noise mast amp to cancel loss of 3 combiners, combine pairs, then combine combiner).

From http://www.techtir.ie/radio-tv/uhf-aerials

The reason Argos, B&Q, Maplin and others sell bacofoil X wings is appearance and cost. The SR series are too boring. They can "fake" the element count high by counting each spike, rather than Reflector, driven dipole, directors. Also they are very cheap having inferior plastic fittings and thin stamped sheet aluminium.

"Proper" Grids use heavy gauge anodized Aluminium and PCB balun in water proof box at centre. Cheap ones are made out of "coat hanger" wire and are visual "clones" copied from appearance of randomly bought template rather than actually designed and tested.

lucernarian

I've tested a grid and 3 grouped contract aerials for reception of Kilkeel, Divis, Clermont Carn, Three Rock, Cairn Hill, Kippure and Mt. Leinster. The grid consistently outperformed the Group B and C/D contract aerials and the Group A contract aerial was slightly better. This was both within the attic space and outside. However, I really must point out that the contracts being used did not have a PCB balun but even with a homemade balun for the C/D aerial, the grid still outperformed it at the frequency the balun was optimal at and indeed on the other channels I tested it on.

http://www.triax.co.uk/Products/Aerials/UHF%20Aerials/BB%20Grid.aspx?productId={33E1944E-6C35-4BA7-A30E-49BABD0ABA49}&Tab=0

Unfortunately Triax's PDF detailing their range of grid aerials with associated graphs have gone walkies so I can tell you that the 12dBi peak (aka about 10dBd and not the 5 or 6 that watty claims) occurred at around Ch 59. At Ch 21 gain was about 7dBi if I remember correctly. I hope my word can be taken on this:pac:

In any case, wind loading can be a big problem with the poor 3 foot poles I've seen used in Drogheda for example. They're also more expensive for minor gains or even losses in performance at Group A.

firemansam1

From reading all these posts, would I be right to say that the Triax Supergain 18(WB) should do the trick mounted in the attic of two storey house in Cross. Or am i reading things wrong.

watty

A bow tie is a dipole, But the spacing on most Grids is low, so you don't get anything LIKE 6dB increase by having four of them

You can get some gain from the reflector. Maybe 3dB to 4dB

Having four of them gives a max of 6dB more, maybe 9dBd to 10dBd total.

12dBi = 9.8dBd max.

OK I forgot about reflector on my post

So a "proper" Grid/Bowtie should be better than cheap Contract and may be marginally better or poorer than SR13 depending on channel.

A "Good" Grid should peak at 12dBd on one channel if it has the larger reflector with angled sides.

Sorry

snaps

i would say, go with what your neighbours have. All this technical talk is even way above me for a simple question asked.

If you can get TV3 in any shape or form analogue wise, you'll get DTT