Dingle town: TG4 good,Net2 less good, RTE1 poor, diagnoses?

dohouch

From my roof at aerial height 3ft (I'm 6ft) I can see the top third of our local transmitter which is about 4 to 5 miles away.

Problem: As in post title TG4 is acceptable. Net2 has a ghost pattern of narrow pin-stripe lines running at an angle of about 80 degrees from the bottom of the screen leaning toward the right top corner of the screen.

RTE1 is the worst,it's snowy and has a wider pinstrip ghost pattern which zig-zags from top to bottom of screen. That is one zig-zag. Two types of aerials are used aound here. One type is finger pointing directly at transmitter, the other type is 18 long fingers and 2? smaller X's on front an this is a right angles to transmitter.

How do I improve reception??

Ulsterman 1690

what is the second aerial for ? Is it for UK channels or are both aerials for Irish stations

dohouch

Thanks,

Ulsterman 1690 wrote:

Could you be a bit more specific as to your location.

Your local knowledge won't help here- Dingle, Co.Kerry (Don't have Google earth on this machine but you can see my house on it)

Ulsterman 1690 wrote:

Also what is the second aerial for ? Is it for UK channels or are both aerials for Irish stations

Both for the 3 locally available state channels, ( some fringe reception here for TV 3)

Ulsterman 1690

Not overly fammiliar with that part of the world but I do know theres a local relay transmitter in Dingle (23/26/33 Vertical) and your TV3 is probably from Mullaghanish (Ch 27 Horizontal)

Someone closer to that neck of the woods can probably be of more help

dohouch

Yeah the numbers are correct 23/26/33. Did'nt realise TV3 had different polarisation. So I learned something. Maybe if I still can I will Dingle to title of origonal post. Thanks

Antenna

Since when has reception been bad?

If you are looping through a VCR and/or satellite receiver try connecting aerial cable directly to TV to rule out problem with one of those loopthroughs.

Make sure both inner and outer on coax plug are making good contact to aerial cable inner and outer

Do you have a masthead amplifier? If these go wonky and oscillate it can transpose lots of (GSM900) mobile phone transmitter interference on top of TV signals.

Try a different TV to rule out fault with your own if possible?

Ulsterman , I don't think the OP has TV3, so he/she has just the one aerial, it could be a wrong type if reception was never good. It should be a UHF Group A (red colour code) or UHF wideband.

dohouch

Hi Antenna, Tried 2 TV sets, same result. How long is the picture poor? Now thats complicated. Been in the house 6 months and got by with attic aerial and 14" TV, have new lager TV and need better signal/picture. And a neighbour 4 houses up, with a new LCD TV, and roof grid and bow-tie aerial asked me to tune hers in. Her picture is realy the one I'm talking about at the moment. Just afraid that with all my work installing a roof aerial, I'm going to end with same picture. Been looking on the net for stuff on UHF (not a lot there)and have to say there is a big GARDA mast pretty much between me and lcal UHF relay. Thhis Gards mast also carries O2 mobile antennae.

P.S. Ch 23 = RTE1 is worst picture, Ch 33 =TG4 is best picture. Ch26 Net2 is somewhere between them in picture quality.

Antenna

dohouch wrote:

And a neighbour 4 houses up, with a new LCD TV, and roof grid and bow-tie aerial asked me to tune hers in. Her picture is realy the one I'm talking about at the moment. .

Did you try a test with another TV at your neighbour’s house?
There have been reports of some LCD and plasma TVs radiating high levels of RF interference. There was a letter published recently in an amateur radio magazine (P.W.) regarding complaints that a Panasonic LCD TV was causing severe interference nearby in the 2 metre (144-146MHz) amateur band. If the TV is radiating interference it would most affect TV reception on VHF and the low end of UHF, I’d expect.

dohouch

Oh, I carried my trusty 14" Mitsubishi CRT up to her house and the story was the same. Ch 23 RTE1) was worst, 26 (NET2)better but not great, and 33 (TG4) good. Probably won't be able to do anything, on the roof, tomorrow as weather forecast is rough.

lawhec

Some things come to mind here, first is the aerial the right group? If it isn't, for example a Group B aerial, TG4 may work OK as its just about off the lower end of the band, while RTÉ 1 & 2 would suffer.

However the clue of the diagonal lines across the screen of RTÉ 1 may help. Has a TETRA mast been deployed locally in the area recently, perhaps the Garda? When it was deployed in the UK those living close to TETRA masts did complain of "tyre mark" like interference to their analogue pictures in the lower part of the UHF band which was more common when the stations being received in the Group A part and are vertically polarised. If this interference is the case, a notch filter may be needed.

watty

There is no Tetra here. It is only one of several system in bid inc custom CDMA. They may not deploy Tetra at all.

I agree that diagonal lines is good indication of interference, maybe from a modulator on VHS, DVD, Games console or local taxi base.

L1011

The ESB have a TETRA system, watty....

watty

How come the ESB got one and the poor Gardai have to use their mobiles still while someone decides what to buy?

Never knew the ESB got one.

I've heard they are looking at replacing Tetra in UK due to "problems".

Ulsterman 1690

Im reliably informed that the trams in Dublin have a digital (not sure if its Tetra) two way radio system while the Police still use unencrypted analouge narrowband FM :rolleyes:

Although for sheer insanity nobody could ever rival the old system used by most (all ?) UK police forces which used frequencies in the FM broadcast band (they probably had more listenership than Radio 3)

I've heard they are looking at replacing Tetra in UK due to "problems".

There have been concerns about TETRA some real others imaginary !

dohouch

Surveyed another neighbours TV picture today. Just 30ft across the road , but a 2 storey house. Her picture was pretty OK on channel 26,and 33. Channel 23 was snowy, which she said was weather thing ( today is very low cloud, humid, and rain never far away. So now I'm going with the idea that chn 23 isn't going to be as good as other two,( weather dependant) and that the interference on the other two may be caused by recently built tall structure between house and transmit. Will try raising aerial to the max on pole and see what happens. This is the easiest thing to do for a first step, apart from getting up on roof, Aerial on chimney.

These are pics 2 aerial types commonly used here, neighbouring house have differnt types. 10 euro job, rods vertical, pointing at transmiter. 30 Euro Ant long axis horiszontal and at right angles to transmiter. Enjoy, closest liknesses I could find. Don't forget transmiter is about 6 miles away,across Dingle harbour, and standing on roof I can see full transmiter mast.

Ulsterman 1690

The 30 euro one is a bowtie grid (In the pic it is horizontal) the 10 euro one is a 10 element yagi (In the pic it is vertical) with slotted reflector

Bowtie grids dont perform well below about ch 30

dohouch

Ulsterman 1690 wrote:

1. The 30 euro one is a bowtie grid (In the pic it is horizontal)
   
2. Bowtie grids dont perform well below about ch 30

I would say Bowtie was vertical in pic, based on long side axis, but you say horizontal, so you are basing that on the elements being horizontal.

I would say those Bowtie Grids are fitted to about 50% of the houses around
and we have, RTE!+Ch23, and Net2=Ch26.

So you reckon the yagi will do better on ch 23 (RTE1 here) I have both, at prsent am using the Yagi but in the attic and it is pointed at gable wall. So tomorrow, now today in about 8 hours time when I'm back up on my roof I will first try Yagi. The Yagi type available locally is very light build quality and probably woun't last as long as grid bowtie outside.

Foggy43

Ulsterman 1690 is correct. 'The €30 one is a bowtie grid and in your picture although looks standing vertically is actually horizontally polarized.' This is probably the one you are using to receive TV3.

The €10 aerial is only used in very strong signal areas. Your relay will be very low powered. I think it is a 100W transmitter. It looks to me as though you are using this to receive RTE1,2 and TG4 from the relay.

This is just my personal opinion but I feel you need a good Quad X yagi for both your relay and TV3.
Something like this http://www.antiference.co.uk/extra.htm

I know they are expensive but when I paid out a large ammount of money for a widescreen TV I was prepared to pay out for a damn good aerial to get the best performance from the TV.

Ulsterman 1690

Surely the answer would be a better version of the yagi (grouped 14 or 18 elements perhaps)

Foggy43

Ulsterman 1690, Probably!

Just my opinion and what experience I have is close or just outside a service area.
Looks like a case of trial and error! Very expensive!

Edit: Talking UHF and not VHF service areas!

dohouch

Got a new aerial set up today. Used a Yagi. Had a look at TV, Ch26 and 33 were fine, but Ch23 had the zig-zag distortion. I thought maybe I could fine tune this away. Went up the road to get the help of a neighbour. Was away 5 mins came back,

and,

Ch23 was fine.

It gets better, the neighbour whose new LCD was also suffering the zig-zag, just paid me a visit asking if I had moved her aerial because her zig-zag was also gone. I of course had not touched it. So whether it was weather, or tansmitter problem I don't know. The funny thing is that this corrected itself in the 5 minutes that I was away fetching the neighbour to help me fine tune my aerial. If this had not happened I could have spent time on a cold roof trying in vain to get a better picture.

And the moral of this story is'''''''''''''''''''' add your own...........

I'm happy enogh now with the picture I have, and no big interest in TV3 at the moment , but I will dtart a new thread l looking for ideas to improve me FM radio reception for TodayFM which is not too bad but Newstalk is poor. Learned a bit on this thread. Thanks to all

watty

A 1/4 wave vertical or even a Scanner Discone for Fm Radio in attic or roof. The 1/4 wave aerial in attic can be made out of 5 pieces of coax. Short center and outer of each piece. make each bit about 75cm long. One held up vertical by nylon cord or fishing line off beam connected to center of feed coax, the other four spread out on rafters/joists all connected to outer of coax feed to radio.

It's not perfect but unbeleiveably better than a wire at back of hifi.

Ulsterman 1690

http://www.gra.cc/finland_model_digital_radio_09.shtml

Interesting article RE: TETRA