TV distribution system project

[Bill Wright]

My own TV distribution system was in need of attention. It had a lot of minor faults. Then I learnt about muxes 7 and 8, and the local transmissions, none of which would be carried by the system without modification. Being more-or-less retired I decided I had the time to do something about it. However I didn?t want to spend money on it. So I decided to do the whole thing from bits and bobs that were lying around. This meant that the existing CCTV equipment would be retained, and the ?in house? signals would be distributed as analogue channels rather than digital multiplexes.

One day I will have a new CCTV DVR, one that will record more channels, so I wanted to get the RF parts of the system ready to carry a few more channels.

In theory we will be able to receive the local TV muxes from Crosspool, Emley Moor, and Bilsdale when they start, and although I don?t expect the material broadcast to be riveting I thought it would be amusing in an ironic way to have the channels available to watch.

This is the ?head-end? schematic.

This is the channel plan.

I?ve had to ?tippex over? various parts of these pages, for security reasons.

Here are some pictures.

Irrelevant, but I found this on a shelf in the shed this morning.

Bill

[spuorgelgoog]

Cobbler's children ...

Is the choc block at bottom left of P1101151 carrying mains? Some of the earth bonding looks rather slender.

Owain

[Stephen]

Like you, I have been hoarding or buying TV aerial system components... I now need to assemble & configure...

I now have 4 Log periodics for Sutton Coldfield, Sandy Heath, Oxford and Waltham.

A FM vertical dipole

2 DAB 5 element aerials

4 Televes Avant 5's

8 CCTV cameras and 8 ch DVR

dish for sky/freesat with quattro LNB

2 off triax 5 x 16 multiswitches

1 multiswitch trunk amplifier

2 trunk 2 way splitter block (to split & feed two multiswitches)

All I need now are 8 off UHF modulators for teh CCTV cameras.

I have already cabled up probably half the rooms so far back to the loft where the new headend is going...

Oh, and a few UPSes too....

I have literally this week bought a used spectrum analyser so I can set everything up correctly.

I'll post some pics when I complete it and we can compare notes....

Stephen.

[Stephen]

Incidentally, is there a cheap way to transpose a local or mux 7 or 8 onto another frequency as there are a couple of co-channel muxes to deal with...

[DerbyBorn]

I wish I could even begin to understand this! But well done - a tidy job.

[Dave Plowman (News)]

I'd also be ashamed of those Belling Lee plugs.

[Bill Wright]

There's no requirement to earth bond when the system only serves one dwelling.

In practical terms, I'm not worried about the earthing of the system. What I haven't shown is the satellite system, which has a lot of commonality with the UHF system, and is earth bonded almost as if it was in a multi-dwelling system.

Of course the large majority of small domestic systems have no earth connection whatsoever. I'm not saying that's right, but...

Bill

[Graham.]

Ha, I was going to say I found it comforting that not quite everything was terminated with Fs.

[Bill Wright]

Not cheap, no.

Bill

[Capitol]

Very impressive. Have you considered a networked CCTV DVR? If the TVs are also networked, then you may be able to view individual cameras without each having a dedicated RF channel. I can do this over a web browser.

For those not having a bits box as good as yours, I have recently been using SPC4 combiners to ease my 8 analogue + DTV channels system noise problems. The results are quite bearable. However I did have to build the 12V DC injection power supply device as these units are designed to be powered from a Sky box. The Mercury modulators from Amazon work quite well, but their output levels are a bit frequency dependent and seem to vary by possibly 15dB over the channels. I estimate between 55 and

70dBuV. I'm waiting for my new signal strength meter to turn up next week to get a better idea. Anyway, beautiful job.

[Bill Wright]

I know you're only sniping at me because I always get the better of you when we discuss politics.

That page certainly doesn't show the proper way to fit bellings. Folding the braid over the outside of the braid clip simply isn't possible with the good quality plugs, because they have a clip that is an exact fit inside the barrel. The braid won't fit. The option given of bending the inner so it 'makes contact' with the pin is pathetic. Soldering the pin after the barrel is fitted is a hopeless idea, because you need to clip a heat sink over the pin near the plastic, and after soldering you need to wipe the pin in case any flux has run along the outside. The soldering method given is very unlikely to give a reliable joint. If the heat comes from the inner core only and not the pin the result will most likely be a dry joint.

Bill

[Bill Wright]

I prefer 'f's, but not to the extent that I'm going to buy new filter blocks when I've got a load of old bellings ones, in need of nothing more than a scrub up and a retune.

Bill

[Bill Wright]

Yes. Eventually I will have to update the DVR, and I guess I'll do something along those lines. But the present job will do for a while.

I think the best ones in that price range by far are the Vision V40 ones. They are very stable. Output is adjustable up to 25dBmV.

I'm waiting for my new signal strength

Thank you. To be honest it isn't as neat and tidy as I'd like.

Bill

[Dave Plowman (News)]

So you're happy with them looking a mess? Figures.

I'm sure you're right. Tell the person who wrote the article. But it still doesn't explain leaving them looking so dreadful. I suppose you just have no pride in your work.

[Bill Wright]

David, you are absolutely pathetic. There's so much I could say, but common humanity forbids it. Go in peace poor David, go in peace. Creep amongst the shadows, as your sort must, until you meet the forgiving peace of the grave. Then Mother Nature can start to forget one of her greatest mistakes. In the history of the world there have been a trillion lives, but even if we include in our reckoning the life of a single-celled creature that died 300 million years ago in what would one day be South London without splitting in two or even contributing to the modern world's supply of oil, your life has been utterly pointless. Once you are gone humanity will breathe a sigh of relief because your suffering will be over and so will ours.

Bill

[UnsteadyKen]

202014.pdf

Very neat and impressive work. And mostly incomprehensible to me:-(

Would you install something this complex for an ordinary home punter, and how does it look to the end user? I.E. could they plug a replacement TV or stb into one of the outlets, run autotune and operate as normal but with extra channels, or do you have to know your way around the system or use manual tune etc to set things up?

[Dave Plowman (News)]

If only.

Those Belling Lee plugs look like they were fitted by an amateur. Or a pro with no pride in his work. No matter how you bluster.

I do realise you post such pictures hoping for adulation from your adoring public. Or something. But I've been around high quality wireman work all my working career, and any broadcast wireman who did work like that would be sacked.

[Dave Liquorice]

It's tight but not excat on all the variations I've come across. What do you do with the braid and clip?

Works in extremis when you haven't soldering kit.

Agreed. Heating just the core is not likely to get enough heat into the pin for the solder to flow well. The heat may also travel to the cables insulation as well. Far better to hold pin in small pointed pliers push the bits together and heat pin/core together briefly and solder. Then assemble the case and cap.

Still it's not a bad description of how to do it far better than some methods I've come across. B-)

[Dave Liquorice]

Looks like it and presumably the wiring from the the ungrommited holes in the larger box above the modulators(?) on P1101149.JPG is also mains. And the hole in that box that doesn't have a blind grommit.

[Bill Wright]

Cheers. Although I think it's rather scruffy! That's partly because it's all second hand bits and partly because I did it for myself!

We have a few systems like that in large houses. They generally use rack mounted equipment though, at least in part.

We have a lot of systems that are similar but with less CCTV. They often include the outputs from several Sky boxes, although with HD that's getting to be outmoded.

No, autotune does the trick. The thing is to arrange the CCTV (etc) channels so that an autotune puts them in the right order.

Bill