Replacing three aerials with one

[amfisted]

Hi all

Just a quick question about TV aerials.

I've got three aerials mounted on a chimney stack, all feeding separate TVs around the house, and I want to replace them with a single unit to receive Freeview. I want to do this because the current arrangement, which I put up myself about ten years ago, is rather unsightly and the reception not brilliant. Not only that, but to my mind one single aerial is less susceptible to storm damage than three.

Which aerial and splitter would peeps recommend, and where best to source them?

Cheers.

 

[Lucid]

The type of aerial you need depends on the local signal conditions and then also your specific reception conditions. Your house could be in an area classed as strong. but your home is directly in the shadow of a very large building. Conversely, your area might be be classed as a marginal area but your house is on high ground and sheltered from competing masts. It's all quite individual. We can offer general advice and point you towards sites such as Wolfbaine for signal strength predictions, but it's still best guess.

As some general guidance most DIY'ers over cook it with the aerial. They fall for the "Wideband super-high gain" marketing ploy and end up with one of the poorly made "sail" aerials that fall to bits after 18 months. If the signal conditions are anywhere half decent then a good Log Periodic aerial is more than ample.

If more gain is needed then a well made Yagi type aerial will suffice. Go for something where the directors and reflector are made from solid aluminium bar rather than bits of pressed aluminium sheet.

For really difficult areas then a grouped aerial is the answer. These are tuned to a specific frequency band to match one's local transmitter.

For a recommended supplier have a look at www.aerialsandtv.com They have excellent technical info and will sell you the right product. Another good retailer is Satcure.

 

[amfisted]

Blimey. I had no idea it was all so complicated. Then again, it probably wasn't in the days when I first decided to put up my own aerials.

Will have a look at that site and do my very best to take it all in, cheers.

 

[dhutch]

In short, based on my experience, you need an aerial fitter in to take measurements and fit a suitable one fo the job and align it etc. Then you need a splinter/booster, which he will also be able to supply or recomend, to send the signal down to the various points.


Daniel

 

[amfisted]

Cheers.

For reasons of thrift/ meanness, for the sense of achievement and also because I like the view from our roof I intend to do it myself, preferably without spending any money except on equipment.

I live on the Wirral and the aerials in my vicinity are pointing towards Liverpool, which, I assume, means that we're tuned to the Winter Hill transmitter. According to Wolfbane, Winter Hill is C/D.

Does this therefore mean that the Yagi 18 C/D would be a good aerial for us? Our Freeview reception from bog standard aerials purchased about ten years ago from non-specialist retailers is acceptable, but not good.

Ta

 

[Lucid]

Blimey. I had no idea it was all so complicated. Then again, it probably wasn't in the days when I first decided to put up my own aerials.

Will have a look at that site and do my very best to take it all in, cheers.

lol.... I can see how it might look more complicated. What I would say though is that it's probably now easier to make a properly informed choice because of the excellent info widely available on the 'net. Sites like Satcure and ATV really help. What you're probably starting to appreciate is why a "one size fits all" solution really doesn't apply to the aerials trade.

 

[SimonH2]

+1 for the Aerials and TV site.

I have a Yagi 18 C/D and even up here on the Furness peninsular I get enough signal that I have passive splitters on some ends, and attenuators on others - I do have a distribution amp, but only because I never got round to taking it out and replacing with a passive splitter. There was an element of "I only want to do this once" so went with the highest gain possible knowing that it's trivial to throw some signal away if you get too much.

However, I'm now into advising a couple of friends on aerial choice, and while it's tempting to go for the Yagi 18 C/D again, I note from http://www.ukfree.tv/txdetail.php?a=SD660144 that Winter Hill is due to move it's muxes (yet again) eventually - moving down into group A territory. So what to do ?
Fit another C/D and accept that I'll probably have to change it in 5 or 6 years ? Fit the Yagi 18 E which might still provide enough signal to not need a new aerial ? Fit something else ? - the XB16E and DY14WB are both more expensive (about twice and thrice respectively), as well as having higher wind loadings.
http://aerialsandtv.com/onlineaerials.html#Yagi18CD
http://aerialsandtv.com/gaincurves.html#CDallcurves

Edit - it's hard to think of a more extreme requirement to put on the aerial - Winter Hill currently transmits at the very top of the band, when it moves it will move right to the bottom of the band. I'm inclined to think that replacing the aerial with a group A when the change happens is best - we don't really want an aerial that's high gain to pick up the non-TV signals that will be taking over in the upper and middle bands.

 

[Lucid]

Log Periodic. Very flat response all the way through the frequency range. Very low wind loading too. Add a variable masthead amp. This one has the gain adjuster on the PSU so makes adjustment easy from besides the TV LINKY

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[Sam Gangee]

I've installed several V10-040 aerials for Winter Hill in Cheshire with excellent results. This log-periodic has been superseded by the V10-28L and -36L, which are even better.
See http://www.satcure.co.uk/tech/best_aerial.htm

 

[amfisted]

Thanks again for more excellent info, particularly the comments about potential band changes at Winter Hill.

We're thinking of selling the house so my aerial update will (hopefully) be the last one at this address. Having read the comments above I think I'll be going for the Yagi18CD.

Cheers.

 

[Sam Gangee]

A Yagi aerial is less "futureproof" than a log-periodic. A Group CD will certainly perform less well in the "A" Group than higher up.

 

[SimonH2]

A Group CD will certainly perform less well in the "A" Group than higher up.

I should hope so - that is after all the purpose of grouped aerials !

As you point out, a Log 40 will outperform a Yagi18 C/D down in group A, and it'll outperform a Yagi18A up in group C/D. But it will have a lower gain in both of those bands than the correct Yagi18, and after the change it will pull in a lot of interfering signals.

I have a feeling that after the great bandwidth sell-off, the last thing people will want is a wideband aerial. The while point of the sell-off is to allow others to buy the bandwidth and use it for more mobile access to videos of cute kittens etc - and you don't really want all those signals (some of which I suspect will be quite strong) swamping the frontend.

Leaving aside the changes due in 5 years or so, it makes sense now to have a group C/D. After the change it makes sense to have a group A or K (some of the group A aerials drop off in gain before C45 which seems to be the planned highest frequency for Winter Hill). It's really a question of whether you fit a wideband now and accept that it's going to be less optimal for both situations, or accept that you'll need a new aerial in 5 years.

Still, certainly at my friends, almost any new aerial and downlead will be better than what she has now !

 

[Sam Gangee]

If you learn about log-periodic aerials, you'll find that the latest ones have an extremely sharp cutoff above UHF channel 60 - so they are only "wideband" in the sense that the gain is relatively constant from 21 to 60.

You'll also find that the gain to the sides and rear is low compared with that of a "Yagi" - meaning that the effective forward gain is around 5dBd higher than the stated 10dBd.

In practical installations, I've found a 40 element log-p was perfectly effective for signal levels down to about 30dBuV/m and invariably beat the heck out of any "Yagi" that it replaced.

The beauty of a flat gain aerial is that you can leave it in place when the band shifts and simply fit a bandpass filter to let through the signals that you want. Use a "Group CD" filter now and change it for a "Group A" filter from 2018 or whatever (if you find that interference is a problem - but it probably won't be).

 

[ImayKnow]

Just a point but NOTHING is actually future proof.

Future proof only refers to what is available / known today. Who knows what the future beholds ? !

 

[Sam Gangee]

Please note that I typed that term in inverted commas and I didn't state that anything was "futureproof". Merely that a Yagi is less so.