Replacing three aerials with one

[ImayKnow]

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.

It was not a dig - apologies if you thought it was.

 

[amfisted]

Update: well, I fitted my Yagi18 CD, connected it to a masthead splitter, then connected the splitter to three TVs via F connectors. The signal to the TV we watch most of the time in our front lounge hasn't improved significantly, if at all. The signal to the two bedroom TVs is appreciably better, which is darned confusing because during the course of this task I've only renewed the cable to one of our TVs, and that's the one in the front lounge. I had to make a joint in the cable to the lounge as I took it down the gable end wall because the length I bought was about two metres short, so I'm wondering whether I'm losing signal as a result of that break; although in making it I did use a proper jointing kit purchased from an online shop recommended on this forum.

I have to say I'm pretty disappointed in the result after several journeys to and from the roof trying to get things right. Using neighbours' equipment as a guide, alignment seems correct, so now I'm wondering whether its actually the TV which is at fault. Shouldn't be: its a Toshiba Regza which is only about three years old.

Even more confusingly, in the rear lounge I have a cheap Alba TV which I bought from Argos, working off a loft aerial, ALSO bought from Argos, and the reception on that one knocks the front lounge signal from my roof mounted Yagi into a top hat. Sheesh!

 

[amfisted]

And finally, just to add...Wolfbane recommends an "amplified high gain aerial" for my postcode--Winter Hill CD--but most of the those who sound informed on the topic seem to regard this advice as surplus to requirements.

I've noticed a number of aerials in my vicinity which are shorter than my Yagi, and which feature a black or brown casing fitted close to the reflectors (not the standard dipole--this thing is the width of the elements), but I haven't seen any of these for sale online. I know that my next door neighbour had such an aerial fitted by a professional installer, although I also noticed that whilst he was on the roof he didn't see fit to go that extra mile and secure the sagging pole.

So many aerials, so little time to work out exactly which one is best for me, and my Toshiba Regza.

 

[SimonH2]

Have you tried moving the TVs around - that would narrow down the problem to the Tv or the feed.

 

[Sam Gangee]

Update: well, I fitted my Yagi18 CD, connected it to a masthead splitter, then connected the splitter to three TVs via F connectors. The signal to the TV we watch most of the time in our front lounge hasn't improved significantly, if at all.

The joint should not make any measurable difference if done correctly. Can you connect a TV directly to the cable before the joint, just to prove this?

What is the total length of this cable?
What is the type number of the cable?
What "splitter" did you use?
How did you terminate its unused (4th) output?
How are you measuring the signal?

 

[amfisted]

Hi Sam

I could connect a TV to the cable just before the joint, but I'd have to go outside and climb onto a stepladder with a TV in my arms to do it. :0)

Length of the cable...about 18 metres, give or take. Type number? Would that be endorsed on the cable itself? I'll go outside and have a look later.

The splitter was one I bought from an online retailer linked to earlier in this thread...http://www.aerialsandtv.com/onlinesplittersandamps.html..its the mast head four way screened external splitter. The unused 4th output is simply left open; should I have blanked this off?

As for measuring the signal, I have no equipment to do this, so just by observing the strength of the TV picture, I'm sorry to say.

Simon, I did try my cheap Alba in the front lounge and the picture is better; but only marginally.

My latest wheeze may be to leave the Yagi where it is, supplying the two bedroom TVs where the signal is adequate, and fitting another aerial on a second chimney stack which is just above the lounge, rerouting the existing cable to the lounge TV. I already have a spare chimney lashing kit, so I only need a new pole. In doing this I would be able to remove the joint and have a continuous cable, as well as eliminating any loss from the splitter. OK, it'll cost more money but I'm determined to salvage something from this mess.

 

[Lucid]

Did you use a meter to align the aerial or just take best guess?

 

[Sam Gangee]

If the splitter is a passive type, you probably need an amp in front.
If it's an amplifier, you need to check that power is reaching it.

 

[amfisted]

Just best guess on the reception; no meter involved, only visual alignment with the general direction of my neighbours' equipment.

Its possible ( but not probable) that reception previous to the commencement of this epic round of roof-based shenanigans wasn't quite as good as my memory tells me, but I'm absolutely certain that its no better now.

Its a passive splitter, and I've fixed it to the chimney breast. Would an amplifier need to be located close to the splitter, or could it be fitted in the roof space below? I'm not sure how I would power an amp; could be a very long run to supply it from the nearest socket.

 

[SimonH2]

The amp needs to be before the splitter - so it boosts the signal to give enough to all outlets after it's been spit. Many are powered up one of the aerial cables - so the PSU goes behind a TV.

Rather than fit an amp before the splitter, it would probably be neater to use a combined amp/splitter (or distribution amp).

Personally, I prefer to fit the amp/splitter in the attic where it's accessible. Generally, the short run of cable from aerial to loft won't be an issue.

 

[Lucid]

You say the signal isn't getting any better. How exactly are you assessing that? What are you looking at onscreen to judge quality?

Just best guess on the reception; no meter involved, only visual alignment with the general direction of my neighbours' equipment.

Without something to help you with alignment you could be chucking away loads of signal. I use a Horizon professional meter when installing, so I can take accurate measurements of signal level at the aerial and down at TV level. I have been on installs where 5 degrees rotation left or right knocks 3dB off the signal level at the mast. That might not sound much. But 3dB is the equivalent of losing 50% of the signal. If you're going to make the best use of the gear you have bought then a DIY signal meter will help.

Have a look at the Fringe Freeview & Satellite Meter linked here. It's much better than the basic £12~£15 meters off Ebay.

Its a passive splitter, and I've fixed it to the chimney breast. Would an amplifier need to be located close to the splitter, or could it be fitted in the roof space below? I'm not sure how I would power an amp; could be a very long run to supply it from the nearest socket.

Do you remember about a month ago, I pointed you towards an combined amp/splitter? see the quote and try opening the link

<SNIP>Add a variable masthead amp. This one has the gain adjuster on the PSU so makes adjustment easy from besides the TV LINKY<SNIP>

That would have done everything for you and been adjustable from the comfort of your living room where you could watch the signal level on your TV or (much better) with a simple signal meter.

 

[amfisted]

Thank you; I'll go back and check out the link for the combined amp/ splitter.

The trouble is, you see, that I'm still in that old mindset where as a householder steeped in a culture of saving money via DIY, you stuck something that looked like an aerial (probably something bought from Argos) on a pole attached to your chimney stack and roughly pointing in the same direction as everyone else's Philex, or whatever...ran a length of cable to your TV, got yourself a picture of more or less acceptable quality and considered the job done. It takes a bit of time to appreciate the message that nowadays, with a little bit of effort and additional expense you can improve your viewing experience way beyond that level of mundanity.

As for assessing signal strength, I'm going up close to my TV and like Mr Magoo, screwing up my eyes to check out the sharpness of the lines on the picture; and currently, they aren't very sharp. If a relatively modestly priced signal meter would help me to make a significant gain in reception I'm certainly willing to invest in one.

Thanks again.

 

[SimonH2]

As for assessing signal strength, I'm going up close to my TV and like Mr Magoo, screwing up my eyes to check out the sharpness of the lines on the picture; and currently, they aren't very sharp.

That doesn't work on digital, and didn't really work well on analogue. On digital, you'll either have a picture, or you won't - if you have it, then the sharpness of the image won't be affected bu signal strength.

If a relatively modestly priced signal meter would help me to make a significant gain in reception I'm certainly willing to invest in one.

It would help.
As an alternative, you need to be able to see a TV from where you can rotate the aerial. You need an index mark on the bracket (or anything else you can reference it to. Rotate the aerial one way until the picture starts "blocking up" or goes altogether - and mark the pole against the index mark. Now rotate the aerial the other way, the picture should come back and then go blocky/off again - mark the pole again. Now turn the pole to midway between the marks and you'll be fairly close to the right position - which might not be the same as your neighbours

 

[amfisted]

So would I be correct in thinking that if the picture is clear and free from interference or blocking but still not of "acceptable" quality, then the problem is probably with the TV rather than with the aerial?

Thanks also for your advice re working out best aerial position without a meter. There's no point at which I can see the TV from the roof, so the missus would have sit in front of the TV and advise me of best aerial position via mobile phone.

 

[SimonH2]

So would I be correct in thinking that if the picture is clear and free from interference or blocking but still not of "acceptable" quality, then the problem is probably with the TV rather than with the aerial?

Correct. If it's not "pausing", doesn't have occasional "blockiness", no pops on the audio - then the DVB signal is OK and any quality issues will be your TV (or TV & STB combination).
Poor DVB signal quality manifests in very distinct artefacts - like the complete picture freezes (sometimes momentary like you've blinked, sometimes more noticeable), screen full of animated squares, and sometimes "choppy" audio.

If you are using a TV & STB combination, make sure you are using the best signal possible.
HDMI (which is digital) would be my first choice - but that is also subject to setting both boxes up to match, and ideally turning off the picture mangling* that's the default for most TVs.
After that, component (RGB).
Then S-Video
And only as a last resort, composite.

RGB and Composite are normally available in SCART connections, S-Video may or may not be supported. But you need to make sure the STB is outputting RGB and not composite - normally in the "TV" section of the STB setup.

* The default settings involve the source (DVD player, STB, etc) creating a digital signal with (say) 1920 * 1080 pixels. The TV then throws about 1/2 of it away (emulating the overscan of the old analogue signal) and resamples the now not big enough image data to fill the screen. I cannot for the life of me fathom the mindset of whoever came up with these standards, instead of having the source produce exactly what's required for the native resolution of the display.