households with vhf aerials only

snaps

Believe it or not, there are households around here with just vhf aerials (only getting 1 and 2 with very bad tv3 and tg4) now to my surprise I fitted a terrestrial dvb t box for a lady yesterday (she wasn't impressed in me saying that she needed a uhf aerial and that her current aerial would be no good for the digital), so i set up the box and like i said i was surprised that i got reception from ch22 castlebar. Now compared to other installs I've done locally her signal was well down, but it worked. I'm just wondering, how reliable will this be? Will bad weather and atmospherics knock out her reception or will she be lucky?

Ronnie Raygun

Probably won't be reliable & even if you made this clear to the lady in question, you'll more than likely get the blame anyway. Maybe better to refuse such installations.

watty

Lots of VHF aerials will be "good enough" for Digital UHF. In 1967 we had only a VHF aerial and TV needed it to get BBC1 & UTV. But BBC 2 worked fine on the VHF aerial or 1' of wire (separate aerial sockets).

Impossible to say in a particular situation unless you have a real meter and know the recommended limits for Eb/No (Digital Signal to noise or Bit Error rate (BER) or Quality). The actual signal level isn't so important as long as enough above the Tuner's internal noise.

watty

Ronnie Raygun wrote: »

Probably won't be reliable & even if you made this clear to the lady in question, you'll more than likely get the blame anyway. Maybe better to refuse such installations.

No, just put a disclaimer that an aerial upgrade MIGHT be needed later.

You can put an 12dB attenuator temporarily to simulate really heavy rain to test, I suppose, but don't forget to take it out.

In absence of knowing parameters and professional test gear a box of different value attenuators is handy. Also you may need to put one in FRONT of a mast or loft amp or distribution amp.

coylemj

Ronnie Raygun wrote: »

Probably won't be reliable & even if you made this clear to the lady in question, you'll more than likely get the blame anyway. Maybe better to refuse such installations.

+1

watty wrote: »

No, just put a disclaimer that an aerial upgrade MIGHT be needed later.

She's relying on a 1960s aerial to receive 21st century TV because she's too mean to pay for a UHF aerial, do you really think a written disclaimer is going to stop her bad mouthing the installer when her neighbours are in for a cup of tea and the PQ is sh1te?

snaps

Situations like this are common. I spoke with her son anyhow, he knows what the story is. He said she'll come to her common sense Soon enough. The shame of it is, I offered her a discount to do the aerial then and there (it wasn't a hard job at all, as the mast was easily accessable), but if I went back I wouldn't do it again for the discounted rate I offered.

Peter Rhea

coylemj wrote: »

She's relying on a 1960s aerial to receive 21st century TV

1960s? Has it escaped your attention that there are still 6 band III sites in operation?

In my area, there were quite a few VHF-only setups for the Monaghan transmitter, although the vast majority would be diplexed with a UHF aerial for NI channels, so any Saorview signal they picked up wouldn't get through anyway.

The Cush

Peter Rhea wrote: »

1960s? Has it escaped your attention that there are still 6 band III sites in operation?

Still use mine to record the occasional programme using an analogue HDD recorder from Mullaghanish RTÉ1/2 VHF Chs. D/G. I have the recoder set to record the RTÉ News Special on RTÉ1 this Wed morning.

Reminds me of a post of mine from 2 years ago - http://www.boards.ie/vbulletin/showthread.php?p=68411633

coylemj

Peter Rhea wrote: »

1960s? Has it escaped your attention that there are still 6 band III sites in operation?

I'm well aware of the fact. My point is that the OP's customer has a VHF aerial that was probably erected in the 1960s, she never bothered to add a UHF aerial to pick up TV3 and TG4 and still won't invest in one for Saorview.

lawhec

coylemj wrote: »

I'm well aware of the fact. My point is that the OP's customer has a VHF aerial that was probably erected in the 1960s, she never bothered to add a UHF aerial to pick up TV3 and TG4 and still won't invest in one for Saorview.

Quite a few people perhaps reckoned that getting a UHF aerial installed for TV3 & TG4 was not worth the additional expense - especially if they could receive terrestrial TV from NI or Wales. I'd estimate that across the border into NI in the parts of Fermanagh & Tyrone served by Truskmore, the amount of people with VHF aerials installed that added an extra UHF aerial for TV3 & TG4 I'd estimate at less than 50%. Even up until about four years ago I was still seeing aerial installations going up with only a VHF aerial aimed at Truskmore and no UHF in the same direction.

However if they value watching RTÉ programmes, then a UHF aerial will have to be considered now (one exception being in my 'hood is if they are set up for receiving the NImm from Brougher).

Quackster

I'm in Tralee with a VHF aerial in the attic directed at Mullaghanish and it has been pulling in a rock-solid DTT signal ever since Mullaghanish went live. Never any problem even in the worst Kerry rain. I haven't even bothered changing it from vertical to horizontal polarisation. It's pulling in a rock-solid signal from Knockmoyle too even though that broadcasts at a much higher frequency.

I reckon way too many perfectly-useful VHF aerials are being unnecessarily replaced just like all the perfectly good CRT TVs being dumped; some of which I'm coming across fly-tipped at the moment.

formerly scottish paddy

Mind you Mullaghanish is belting out such power (200kw) I wouldn't be surprised if you received it on a knitting needle!

Peter Rhea

Peter Rhea wrote: »

1960s? Has it escaped your attention that there are still 6 band III sites in operation?

OP didn't say which VHF band: could be a band I aerial on Maghera for all we know. Switched off in 1999 IIRC?

Quackster wrote: »

I reckon way too many perfectly-useful VHF aerials are being unnecessarily replaced

Their intended 'useful' purpose is to offer signal gain on the band III tv frequencies.

watty

Each case needs to be evaluated separately.

Some people can get reliable reception with a knitting needle in the aerial socket and some need big aerial on a big pole.

Many people with VHF only aerial need a new UHF aerial, but not all.

The VHF aerial of course may be useful eventually for DAB or some other Band III service and can also be useful for VHF-FM band II

Quackster

formerly scottish paddy wrote: »

Mind you Mullaghanish is belting out such power (200kw) I wouldn't be surprised if you received it on a knitting needle!

True, but it just goes to show that there's a hell of a lot of VHF aerials in the South-west that probably don't need replacing!

Peter Rhea wrote:

Their intended 'useful' purpose is to offer signal gain on the band III tv frequencies.

Their intended 'useful' purpose is irrelevant after ASO. If they're during the job for Saorview and save on a potentially expensive aerial replacement, that's what matters. The general message should be that people experiment with their existing aerial setup first before investing in any aerial work.

lawhec

Quackster wrote: »

Their intended 'useful' purpose is irrelevant after ASO. If they're during the job for Saorview and save on a potentially expensive aerial replacement, that's what matters. The general message should be that people experiment with their existing aerial setup first before investing in any aerial work.

That isn't necessarily bad advice - however using an aerial to receive a signal on a frequency it wasn't designed to receive - especially nowhere near its design - will act in a fashion not dissimilar to a random piece of metal or wire. In areas where the signal is very strong, there is a good chance that you'll get away with it. It also helps that DVB-T is much less inconvenienced by multipath interference - for analogue UHF reception a VHF Band III aerial will have no effective directional properties to help null against ghosting which except in some very unusual or horrendous cases won't affect digital reception except for co-channel interference from another transmitter.

It's also the case the the above scenario only applies if a VHF Band III aerial was the only aerial being used for TV reception and it wasn't diplexed with another TV or FM radio aerial. In places which had a VHF Band III aerial for RTÉ1 & RTÉ2 and a UHF aerial aimed at either NI, Wales or a local deflector, any Saorview reception would be dependent on the UHF aerial - if that wasn't successful then in the case of where a deflector once existed, the UHF aerial might be OK to use for Saorview if realigned depending on condition and aerial group (though if you're going to go up and do that, you may as well take the VHF aerial down unless you have other plans for it), otherwise if you want to retain Freeview reception then a new UHF aerial and diplexer will be needed.