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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Alarms, Phones, Aerials, CCTV & Datacomms >> Bloody telly! https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1204150943 Message started by The_Trician on Feb 27^th, 2008, 10:22pm

Title: Bloody telly!
Post by The_Trician on Feb 27^th, 2008, 10:22pm

Right - I have a stone-0age set-up, just an ordinary aerial with a amplifier and mains-powered box thing behind the telly.

Since we've had all this weird high pressure weather, the whole lot has virtually become unusable. So, I need to go for a digital aerial and set-top box.

I don't want Sky or a dish - just a new digital ariel
I have tried one of the links in the satcure and other links and it tells me that digital reception is not available. I live in a semi and my neighbour gets it fine!

Sat cable? Is it better than plain ordinary 75 ohm co-ax? If so, what brand of sat cable should I get - any part numbers?

Ariels - I know ferk-all about em. Have doing some reading and checked here - which came up with this -

http://www.wolfbane.com/cgi-bin/tva.exe?DX=L&HT=10&OS=DE4+3PD

If I ferk off to the aerial shop what model/make do I ask for?

Ta!

TT

Title: Re: Bloody telly!
Post by CWatters on Feb 28^th, 2008, 12:36am

Hi TT,

Don't rush off out to by a "digital" aerial as I believe you have a problem. According to wolfbane site your area is NOT yet covered by a digital transmitter. Neither the Matlock transmitter nor the one at Bolhill are due to go digital until 1st May 2011....

http://www.ukfree.tv/shutdowndetail.php?tx=SK297589
http://www.ukfree.tv/shutdowndetail.php?tx=SK295552

Are any neighbours able to pick up Freeview and if so which transmitter are they pointed at?

There are two wolfbane sites. One for Analogue and one for Digital. To work out what you need you normally have to look at the results from both and merge the data. By the way there is no such thing as a "Digital TV aerial" despite what some manufacturers put on the packaging! Aerials marketed as "Digital" are generally wideband aerials and these are to be avoided unless absolutely necessary because wideband aerials have lower gain than narrow band aerials!

First we head off to the the Digital site..
==========================

http://www.wolfbane.com/cgi-bin/tvd.exe?DX=M&OS=DE4%203PD&HT=10

This says that there are currently no local digital transmitters and no distant ones either! This is probably because the wolfbane site takes into account the terrain (hills!) between you and the transmitters. For example if you tell it the aerial height is 75 rather than 10 meters it will tell you that you should be able to pick up the Waltham transmitter 37 miles away. For that you would need a really big wideband aerial mounted as high as you can get it. It would probably also need to be fitted with a mast head amplifier (not a back of set booster amp - they are the devils work). A local professional installer who knows the local terrain might suggest another transmitter and other aerial options but I do believe you would need a skilled professional to set this up at the moment - assuming it's possible at all. A tree in the wrong place may make all the difference.

Now to the Analogue site...
===================

http://www.wolfbane.com/cgi-bin/tva.exe?DX=M&HT=10&OS=DE4+3PD

This says your area is served by two transmitters. One at Bolehill 2 miles away and one at Matlock itself. These are very very low power transmitters - just enough to cover the immediate area. The table says you need:

For Matlock: a "Group A, vertically polarised, amplified extra high gain aerial.
For Bolhill: a "Group CD, vertically polarised, amplified extra high gain aerial.

Note: A "Group A" aerial is a narrow band aerial designed to cover the lower part of the TV band. It will have higher gain than a typical wideband aerial. A group A aerial pointed at Matlock will be also perfect for recieving digital from Matlock when it goes digital in 2011.

http://www.ukfree.tv/shutdowndetail.php?tx=SK297589

Please don't let some cowboy put up a cheap wideband aerial pointed at Matlock because that's all he has in the van. A wideband is not really suitable for Matlock even if it appears to work.

Summary
======

You may have to wait until 2011 for digital but consult a professional to see if there is any chance of getting it from a distant transmitter before then.

See above if you want a new analog aerial. I'd be tempted to go for a large Group A pointed at Matlock, possibly with a mast head amp. This should work fine when Matlock goes digital.

Note your existing aerial might already be the correct type. It might just be old or need realigning or the down lead might be waterlogged.

Consider having that booster replacing with a low noise masthead amp. If you need to feed more than one TV use a low gain Distribution Amplifier rather than a booster.

Sorry for any typos. In a rush.

Title: Re: Bloody telly!
Post by CWatters on Feb 28^th, 2008, 7:54am

Bit more useful stuff...

Vertically and Horizontally polarised refers to the way it's mounted - eg You buy a Group A aerial then mount it with the elements either vertically or horizontally....

The aerial group can sometimes be identified by the colour of the plastic bung on the end pointed at the transmitter...

Bung Colour, Group, (Channel coverage)
Red A (21-37)
Yellow B (35-53)
Green CD (48-68)
Brown E (35-68)
Grey K (21-48)
Black W (wideband 21-68)

A typical gain chart for aerials designed for different groups...

Note how the gain for a wideband (black solid curve) is so much lower than that for a Group A aerial - particularly in the Group A part of the band! If (as in your case) analogue and digital will both be in Group A (Matlock from 2011) then you really should avoid a wideband and stick to a Group A.

Finally .. a big aerial on a tall pole needs carefull mounting. The pole might need to be larger diameter than normal - perhaps 2" - and two widely spaced wall mounts (perhaps 2-3 feet apart) should be used rather than a single bracket.

The aerial mounting brackets on the left of this picture are a good example...
http://www.wrightsaerials.tv/007chimneypots.htm

This rouges gallery of bad examples is worth a read..
http://www.wrightsaerials.tv/roguesgalleryview.html

Title: Re: Bloody telly!
Post by The_Trician on Feb 28^th, 2008, 10:10am

Hi C/W,

Many thanks for that - I'll take a look at what the neighbours have on their chimney stack and see if I can spot the coloured bung.

I was aware that digital reception is supposedly not available, nor it seems, are there any plans to make it so - according to the BBC and a few local radio/TV retailers.

The Matlock transmitter is actually a couple of hundred feet below us and is sited in a gorge - I live high on a hillside and although we can't see it, we overlook the top of the transmitter mast.
No one up here has been able to utilize this transmitter for reception, and most are either Waltham or Bolehill.
Bolehill is actually at a similar height, but is round the corner from us further up the valley - and certainly not in line of sight.

I think our aerial is actually pointing at Waltham, despite it being the farthest away.
Any info on what cable I should use?
More soon

TT

Title: Re: Bloody telly!
Post by CWatters on Feb 28^th, 2008, 1:49pm

Ok here is the gen on Waltham...

http://www.ukfree.tv/txdetail.php?a=SK809233

I anticipate you will have a lot of problems getting a reliable digital signal from Waltham for a number of reasons but perhaps worth giving it a go..

Your neighbours may have a variety of aerial groups depending if they were upgraded to get Channel 5 but have/havent got digital yet. They may not be the best source of info in this case.

The analog transmissions from Waltham are in Groups C/D and the digital are in group A. These are at oposite ends of the band so a large wideband aerial will be required. It may also need a mast head amp but the rule is try a bigger aerial first then an amplifier. Mast head amps are almost allways better than back of set amps. There are good technical reasons for this to do with losses in the cable in relation to the amp.

There are several other problems which may make recieption difficult or unreliable...

Most digital transmitters are broadcasting on reduced power to avoid interferring with the analogue transmitters outside the area. The Waltham transmitter is broadcasting Analogue at 200,000 Wats but digital at only 7,333 Watts so it's a bit like trying to see the stars in the daytime - they are still there but swamped by sunlight. Too much gain in the aerial or booster amp and the analog signal may cause problems for the digital. Bit of a catch 22 here as you need some gain as the digital is weak and far away. This may only be solved when the analogue channes are switched off and the power turned up on the digital in May 2011.

Meanwhile not all the channel groups are at the same power. You might get multiplex 1 (BBC digital channels) ok but not multiplex 2 (ITV channels) or some of the other Muxes.

See the channel table in the middle of this page for "Mux effective power".. .

http://www.ukfree.tv/txdetail.php?a=SK809233

Many of these problems are down to a lack of spectrum. It's hard to fit all the transmitters on the map and allocate frequencies so they don't interfere with each other.... yet the government still wants to sell it off "spare spectrum" to the mobile phone companies. Mad in my view.

Try this page for info on the cable and it's routing...

http://www.aerialsandtv.com/cableandleads.html

Pitty you don't live a bit nearer them as they have a good reputation.

In brief - For the TV down lead they suggest using RG6 or better still double screened H109 / CT100 Type Satellite Cable.

Edit:

This is the wideband aerial they recommend for weak signal areas...

XB16WB: http://www.aerialsandtv.com/atvschoiceofaerials.html#XB16

but even though this is a good aerial they suggest that two seperate aerials might be better...

Quote:

Note, even the XB16WB does not give high gain at the bottom of the frequency range, there is no wideband aerial that will. If you must have a wideband, and you require more gain at the bottom of the band, you`re best option is to diplex an A group with an E group, or even an A group with another (high gain) wideband if you already have one of these.

So expect to have to do some experimenting. If an aerial like this doesn't work you are probably looking at two seperate aerials.

Title: Re: Bloody telly!
Post by londonman on Feb 28^th, 2008, 4:49pm

If you do replace the aerial then most definitely yes,.....go for the proper satellite or digital type cable. 'Normal' co-ax is no good. To give you an example...I am line of site to Ridge Hill - 14 miles away. Nothing in the way. They're on a hill. I'm on another one. Got a Freeview box and some channels couldn't be received. Bought a new aerial. No improvement. Replaced the cable., Bingo.

Title: Re: Bloody telly!
Post by CWatters on Feb 29^th, 2008, 9:59am

Don't forget there is also Freesat. Not all freeview channels are on Freesat but it does have some in HD. Official start this spring.

http://www.freesat.co.uk/home.php

Title: Re: Bloody telly!
Post by RabbitRabbit on Feb 29^th, 2008, 7:40pm

What a load of hassle Dave to watch a load of crap. Get a book mate or better still spend more time on sparky forums they are a LOT more fun ;D

Title: Re: Bloody telly!
Post by The_Trician on Feb 29^th, 2008, 8:04pm

Agreed - but I do like 'Question Time, A week in Politics and Ashes to ashes.

Not only that, but my live wouldn't be worth a light if my missuss doesn't get her weekly dose of 'Fatbitch UK' or You are what you eat or whatever they call this freakshows!

There's enough info in this thread to make me just want to sit down and ring an aerial contractor to sort it! My head is spinning with it all!

I am going to print it out, summarize the salient points with a highlighter, and do some more studying!

Many thanks to all who have contributed thus far peeps.

Cheers

TT

Title: Re: Bloody telly!
Post by The_Trician on Mar 4^th, 2008, 5:59pm

OK - Have just taken a couple of photos - the smaller darker coloured aerial on the left is ours. No idea what types they are though. It looks to me that they are both pointing somewhere out towards either Sutton Coldfield, or Waltham?

The bright metal coloured one is our neighbour's - THEY CAN get Freeview.

Title: Re: Bloody telly!
Post by Lectrician on Mar 4^th, 2008, 6:14pm

Your neighbours aerial is not a high gain type - It is actually fairly short. You must be fairly close to a transmitter. Georgraphy plays a part. Are you high, or in a valley. Hilly around you?

I can just make out a mast head amplifier on your neighbours aerial.

PM me your postcode and I will take a look to see which transmitter is best for you.

It looks like you are due a new aerial, and from the age of it, a new coax drop would not go a miss either.

Is the aerial feeding one TV only?

Title: Re: Bloody telly!
Post by CWatters on Mar 4^th, 2008, 6:33pm

His post code is hidden above ;D

I think all I can tell from the photos is that you probably have a "Grouped" aerial designed for part of the transmission band (all the little rods/elements are the same size and have constant spacing = optimised for one set of frequencies).

To get digital from Waltham (if that's where the neighbour is pointed) you need a wideband aerial instead. Your neighbours aerial looks like it might be a wideband but a bit hard to be certain from the photo.

Is your channel line up as follows BBC 1 on 58, BBC2 on 64 and ITV on 61? If so it will be Waltham.

Title: Re: Bloody telly!
Post by Lectrician on Mar 4^th, 2008, 7:12pm

The back end elements on the neighbours do look tighter grouped.

Title: Re: Bloody telly!
Post by The_Trician on Mar 10^th, 2008, 11:17am

Just a quick recap - Cable types - Satellite ok, but is there a specific brand or part no I should be looking for?

Are all Sat cables the same quality and specification?

TT

Title: Re: Bloody telly!
Post by Lectrician on Mar 10^th, 2008, 5:06pm

http://www.screwfix.com/prods/94205/Electrical/Cable/Coaxial-Cable/Labgear-Satellite-Coax-Cable-Black-100m;jsessionid=VP42LRZ21MCN0CSTHZOCFFI

http://www.satcure.co.uk/accs/page8.htm#WF100

Look for foam dielectric - This is more suitable for outside use than the plastic air spaced dielectric.

Copper foil and copper braid screened.

WF100 is the foam and CT100 is the plastic. There is also PH and a few others depending on manufacturer.

Title: Re: Bloody telly!
Post by plugwash on Mar 10^th, 2008, 8:00pm

CWatters wrote on Feb 28^th, 2008, 7:54am:

Note how the gain for a wideband (black solid curve) is so much lower than that for a Group A aerial - particularly in the Group A part of the band! If (as in your case) analogue and digital will both be in Group A (Matlock from 2011) then you really should avoid a wideband and stick to a Group A.

Seems to only be about 3-4db of difference, an ammount easilly made up for by going for a slightly bigger ariel and having a wideband avoids problems if you want to change transmitter or if they start broadcasting some freeview muxes outside of your areas normal band.

Title: Re: Bloody telly!
Post by CWatters on Mar 11^th, 2008, 8:16am

Depends how marginal your conditions are. Might only be a difference of 3-4db but on ch21 even a large wideband might only have 6.5db to start with. Just about all transmitters will revert back to a group after DSO even if they are out of group during dual running.

The Great Wideband Debate..
http://www.aerialsandtv.com/atvschoiceofaerials.html#ATVsChoice

Title: Re: Bloody telly!
Post by The_Trician on May 2^nd, 2008, 3:17pm

Right chaps - Today I have had a company (SKYFORCE LTD) to come out and quote.

Spec is as follows -

1 x 'DMX10' antenna.
Feeding 3 points.
1 x masthead amp & power unit.
Cable is CT100 with foam dialeteric.
Price - £259.68

I have to supply & fit the backboxes and supply the front outlets.

Also, can anyone give me some info on outlet plates?
I was in my wholesalers yesterday, and he was talking about 'insulated' and 'non-insulated' types - what applies to what here?
I want to fit MK LOGIC white plates to match the socket outlets.

Comments please?

Ta

TT

Title: Re: Bloody telly!
Post by Lectrician on May 2^nd, 2008, 5:54pm

Sounds a reasonable price actually!

Isolated / Non Isolated. Not insulated/non insulated ;)

Isolated outlets have a capacitor in them, and effectivly 'isolate' your TV and fly lead from the distribution system. The only reason this is done is so if your fly lead or TV presented a short or something to the amplifier, it would prevent it from shutting it self down. They are used in blocks of flats etc so one neighbour does not affect another. There is a smidge of a loss of quality, but nothing noticeable really.

Go for NON isolated.

Title: Re: Bloody telly!
Post by CWatters on May 2^nd, 2008, 10:00pm

That spec looks ok to me. The DMX10 is a 52 element aerial. Should look like this..

Ask how they are driving the three seperate faceplates from one aerial? They should be using a masthead amp with three seperate outputs rather than passive splitters (T joints).

If the mast head amp they bring has four outputs perhaps ask the fitter if it would be possible for him to run a wire from the un-used output into the loft and leave a few meters coiled up. Might come in handy later.

I could suggest other things to do if you are ever likely to want to distribute Sky to multiple rooms but perhaps not complicate things.

Title: Re: Bloody telly!
Post by The_Trician on May 5^th, 2008, 12:51pm

The spec refers to 'amp & power unit' so I am guessing the 'amp' bit refers to a masthead amp.
Would I be correct in assuming that an isolated outlet would stop the power and the signal being transmitted from the amp to the tv set then?

TT

Title: Re: Bloody telly!
Post by Lectrician on May 5^th, 2008, 1:32pm

Na - the signal is still passed, but there is a tiny loss. The isolated outlets litterally simply protect the amp from short circuit type faults.

Amps have built in protection to shut down on a fault on an output. In flats etc, it would be a pain if everyone lost TV because someone was trying to use a dodgy fly lead to connect the TV.

In saying this, many amps these days have 'isolated outputs', where only the output thats faulty shuts down. However, there are still many that will shut down completely, or simply be unable to work with a shorted output.

Go for non-isolated. That is what all domestic installs use.

An amp with four outputs will be far superior to an amp with a splitter in the loft, unless the splitter is powered. Ask if the masthead amp has a single or four outputs.

The masthead amps, and many loft amps fitted by aerial guys, run on 12v DC which is derived from one of the coax downleads (outputs). This is usually from the main TV location, and the powersupply that sends this 12v up the coax is placed in line with the coax at this point. This is far easier for aerial guys, as they do not need to mess with lecky in the loft. It can however be a pain when you move house - most people take the powers supply with them, thinking it is the booster. Then the next folk in the house have no TV reception! In away, I wish the aerial guys would fix the power supply to the wall or skirting atleast!

Title: Re: Bloody telly!
Post by Twobarrows on May 5^th, 2008, 3:46pm

The_Trician wrote on May 5^th, 2008, 12:51pm:

It will stop the Sky remote working in other rooms remote from the Sky box itself.

Title: Re: Bloody telly!
Post by Lectrician on May 5^th, 2008, 6:46pm

wrote on May 5^th, 2008, 3:46pm:

The_Trician wrote on May 5^th, 2008, 12:51pm:

It will stop the Sky remote working in other rooms remote from the Sky box itself.

But he is talking about a downlead from an aerial, not an uplink to an additional TV from the sky box. Agreed though, the isolated plate would block the 9v required for the eye.

However, TT, you must make sure that which ever location is going to have the power supply does not use an isolated outlet plate, as this would block the 12 to the booster.

Title: Re: Bloody telly!
Post by Twobarrows on May 5^th, 2008, 6:59pm

>But he is talking about a downlead from an aerial, not an uplink to an >additional TV from the sky box. Agreed though, the isolated plate >would block the 9v required for the eye.

Oops, forget we were talking about aerials :-) I'm so used to my set-up with just Sky.

Title: Re: Bloody telly!
Post by CWatters on May 5^th, 2008, 9:51pm

MK have non-isolated TV outlets in the Logic series...

http://www.tlc-direct.co.uk/Products/MKK3520.html
and
http://www.tlc-direct.co.uk/Technical/DataSheets/MK/TelephoneSkts.pdf

Looks like the part you want is K3520 WHI = TV/FM Co-axial socket(single). These have a socket similar to the aerial connector on the back of your TV.

Aside: Personally I have a slight preference for threaded "F" connectors as found on the back of Sky boxes. MK also do those Part number K3525.

http://www.fastlec.co.uk/images/mk/k3525whi.jpg

The F connector is slightly better quality than a regular aerial socket connector but if you go for face plates with F connectors you need special leads with an F plug on one end and an TV aerial connector at the other. Maplin carry them but perhaps not many other highstreet stores.

Title: Re: Bloody telly!
Post by Twobarrows on May 5^th, 2008, 10:08pm

Quote:

The F connector is slightly better quality than a regular aerial socket connector but if you go for face plates with F connectors you need special leads with an F plug on one end and an TV aerial connector at the other. Maplin carry them but perhaps not many other highstreet stores.

F connectors are not only superior in quality they are a doddle to fit and also dirt cheap! Use an adaptor to convert back to the normal coax plug style.

Title: Re: Bloody telly!
Post by The_Trician on Aug 15^th, 2008, 11:56pm

Gents -

Further to my previous queries!

I have now reached a point in my house renovation whereby I need to route some CT100 cable in quickly before the plasterer buries everything!

So, Am thinking the following -

Get some kind of distribution box put up in the loft and run cable down from there to outlet in room to be plastered.

At a future date, get aerial man to come and fit aerial, masthead amp etc, and downlead from aerial to loft. I can run a dedicated 240V supply to the loft to be specifically used for powering any TV stuff up there.

I can then run from the loft to each room as I move through the house doing the renovations.

What is the best type/brand of distribution box to get?
Am most likely looking at something with 4 or 6 outlets.

TT

Title: Re: Bloody telly!
Post by The_Trician on Aug 16^th, 2008, 11:19am

Just been and bought 100 metres of CT100. Whilst there, I asked about these 'Loftbox' thingies. £48+VAT!!!! :o :o :o

Took a rain check on it and have just been googling. It seems that the much-vaunted Loftbox solution ain't the best game in town as far as reception to other rooms is concerned.

TT

Title: Re: Bloody telly!
Post by Lectrician on Aug 17^th, 2008, 11:15am

You dont need a loft box if you are not installing sky TT.

Just get a digital ready distribution amp.

Title: Re: Bloody telly!
Post by The_Trician on Dec 15^th, 2008, 10:20pm

Is something like this any good?

http://www.screwfix.com/prods/30624/Electrical/TV-Range/Amplifiers-Distribution/Labgear-Remote-Power-Distribution-Amp-6-Way;jsessionid=T5PJ03HV3JWRQCSTHZPCFFI#

TT

Title: Re: Bloody telly!
Post by CWatters on Dec 16^th, 2008, 8:44am

For distributing TV around the house yes it should be fine.

I note that it's designed for situations where there is no power in the loft - its sends power from the power supply unit up the coax to the distribution amp in the loft. If you have a power up there it might be neater to put the power unit in the loft or get one with a built in power supply and mains plug

Did your aerial install work out ok? Did they need to install a mast head amplifier or similar? If so the way that's powered might cause complications. Some mast head amps are powered up the cable as well and you might need a distribution amp that provides that (this one doesn't).

Title: Re: Bloody telly!
Post by The_Trician on Dec 16^th, 2008, 9:27am

Hi,
Not had the aerial job done yet - but it'll be during the next week or so - we've only just finished the building wks and the lounge is now painted.

Could do with the job being done before xmas in time for the latest Wallce & Gromet on Xmas Day!

TT

Title: Re: Bloody telly!
Post by The_Trician on Feb 23^rd, 2009, 9:01pm

Finally got this bugger sorted out once and for all!

Plumped for a Freesat dish with 4 way lmb thing, 4 lots of cable into loft with one presently feeding a Grundig Freesat box.

Oh boy, there ain't half some shitt on satellite telly!

Now I know why I feel that I haven't missed anything great for the last 10 years or so!

TT