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Picture Break Up - Sutton Coldfield Transmitter

Ezra Pound said:
Introducing the splitter is reducing your signal by half, this is not a problem if you are next door to the transmitter, but at nearly 30 miles away you can't afford the loss, all connections (however good) will introduce some reduction to the signal and are best kept to a minimum
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Thanks for the reply - I don't understand where you are seeing the signal being reduced by half by the splitter, excuse my stupidity but I thought it was only making a slight difference. When using the splitter with no booster v not using the splitter or booster I get about 2-3% less Signal strength as shown on the tables in post #27 (http://hummy.tv/forum/threads/picture-break-up-sutton-coldfield-transmitter.6056/page-2#post-78957

Or is it a simple case that like a piece of cake, by introducing the splitter I am cutting it down the middle? Meaning half goes to the lounge and half goes to the bedroom (when I wire that in).
 
Leonthefixer said:
I don't understand where you are seeing the signal being reduced by half by the splitter, excuse my stupidity but I thought it was only making a slight difference. ).
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Look for the insertion loss of your splitter (like the one HERE), it shows a UHF loss of 4.5dB, this scale is logarithmic and 3dB is the Half power point, see explanation HERE, the splitter is making a lot more than a slight difference. With the other output of the splitter not being connected you probably won't be losing the full 4.5dB BUT it will still be a large proportion of it
EDIT
More info, here :-
http://www.aerialsandtv.com/ampsandsplitters.html#Splitters
It should always be remembered that it is the splitter (and the cables from it) which
represent the load on the signal, it is irrelevant whether or not there is a TV on the end.
Click to expand...
 
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Yes, UHF isn't exactly like light, but it's not exactly like DC electrical current either. It "leaks", so any hole in the pipe loses some of it (to put it very, very simply). The purpose of a splitter is to try to make half of it go down each leg (and lose as little as possible in the process). Disconnecting one leg doesn't make all of the signal go down the other leg.
 
Loosing half the signal (which is a fact) will not reduce your signal 'percentage' to half its previous value, due to the dubious way the signal level is measured (probably approximately logarithmically) and the fact that half power is 0.707 voltage not 0.5 voltage.
Your tables confirm the signal loss of around 2-3% when the splitter is in circuit.
 
Thanks for that info - I think I will need to spend more time reading over it as I can't really get my head around it at the moment. The reason I thought it wasn't making much of a difference was because the signal strength readings from the Humax box were not massively different, only showing a 2-3% difference. But those readings I am guessing aren't giving me the whole picture (excuse the pun) as you are saying that I am actually getting a big difference, losing half my signal with the splitter.

From what I understand after what you said it is actually the splitter that has been causing the picture issues, not the booster - or am I totally missing the point?

So my options are to install an amplifier prior to the splitter if I want to reintroduce a splitter or just do without the splitter which isn't an option really as I want a TV point in my bedroom down the line.

Tbh I am more confused than ever after reading that lot and don't get why the splitter has all of a sudden started to cause the issues when it has been fine for months :-S
 
Leonthefixer said:
as you are saying that I am actually getting a big difference, losing half my signal with the splitter.
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Yes, but if your signal is good enough in the first place, it makes no practical difference (purists may argue)
From what I understand after what you said it is actually the splitter that has been causing the picture issues, not the booster
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Could be either or neither, but I still go for dodgy joint or interference
- or am I totally missing the point?
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I don't think so
So my options are to install an amplifier prior to the splitter if I want to reintroduce a splitter or just do without the splitter which isn't an option really as I want a TV point in my bedroom down the line.
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Until you do, then I would probably leave both out providing the picture on your main TV is satisfactory, Why pay for the 'lecky to run a booster when it's not required. Doesn't the booster have more than one output?
Tbh I am more confused than ever after reading that lot and don't get why the splitter has all of a sudden started to cause the issues when it has been fine for months :-S
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I don't think it has, nor the booster. I think it's something else. You may just have fixed it with your poking about with the plugs etc. You don't say whether the picture breakup is still present or not.
 
Thanks for that Trev - The picture was fine last night - see post 39 (http://hummy.tv/forum/threads/picture-break-up-sutton-coldfield-transmitter.6056/page-2#post-79028). I haven't watched any TV today so not sure if it is all still fine.

I forgot to say the Splitter I have is one of these from Aerials & TV (http://www.aerialsandtv.co.uk/onlinesplittersandamps.html#Taps) which states: "8 / 3 * = 8dB side loss + 2.8dB through loss"

wp7ec14b63_01_1a.jpg
 
Trev said:
Your tables confirm the signal loss of around 2-3% when the splitter is in circuit.
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You have to take into account the there will be an AGC (automatic Gain Control) in the Humax that will be amplifying both signal and noise on it's input
EDIT
Leonthefixer : The item you show is a tap rather than a splitter, the main 'through' has a loss of 3dB, with the other (side) output having a loss of 8dB, so the 'side' output will be of little use to you anyway as the signal will be roughly 15% of the input level
 
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For info: dB measures signal power, but the receiver circuits are sensitive to signal voltage. However, signal power appears as voltage when the line and termination impedances are taken into account, so the numerical relationships are complicated.

All that really matters is that an amplifier increases the signal and the noise together, and a splitter (or tap) divides the signal+noise between multiple outputs and adds a bit more noise while losing a bit of signal for good measure. A distribution amp is just an amp with a splitter built in (although usually very high quality).

High quality aerial cable (eg satellite downlead) has significantly lower signal losses at UHF, and when used for any long runs can cure a lot. Normal single-screened TV aerial cable (usually brown, also available white or black, about 8mm diameter) is OK, but the thin cheap stuff (6mm or less) sold as extension leads is almost useless. Ditto plastic-bodied aerial plugs.

Armed with that knowledge, it's just a case of seeing what works.
 
The cable I have used is good quality Webro WF100 cable, which I understand is one of the best you can use. The length of the cable run is really quite small. Probably about 10 meters from aerial to lounge at the very most, I think it is actually less.
 
Leonthefixer said:
Sorry that was my mistake. I have one of these splitters that look very much the same as the taps:

http://www.aerialsandtv.co.uk/onlinesplittersandamps.html#InternalSplitters
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Either way, you're much better off without it, I appreciate that the system worked with the splitter and that there must be something else that changed to cause your problem, but you still give yourself a better margin for error without it, unless you can get some signal boost before the splitter
 
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I think I will just see what works as has been suggested as I don't really understand all the different bits about gaining and losing db's and things like Automated Gain Control etc. To be honest I am more confused now than I was before ;-)

If the picture carries on being okay with the booster removed and the splitter removed and the cable joined by an inline connector, I will try adding the splitter back in. I know Ezra Pound has said I am much better without it but it means I can only feed one TV, the lounge, when I want to be able to feed two TV's.

If that leads to issues I will have to put an amplifier in before the splitter if I am understanding things correctly as that is the best place to put it. If that doesn't work I guess I will just have to install a second aerial to run the bedroom tv and redo the cabling to the lounge tv with a straight run from the original aerial. Though not really sure where I could put a second aerial.
 
Having a working system is a good place to start from :), I would suggest you only make one change at a time so that you can trace any problems, also remember that each intervention (say removing an item and putting the same item back) can give different results if the disturbed connections are not as good (or bad) as they were before, although this is less of a problem with 'F' Connectors
 
Thanks for that Ezra, I think I will proceed as follows.

1. Leave it as is for a few days and see if the picture remains okay
2. Assuming it is still okay I will add the splitter back in
3. Leave it a few days and see what happens.
4. a) If everything is okay and no picture break up then fantastic
4. b) If picture break up I will phone up TV & Aerials and ask their advice about putting an amplifier in or whether I should just install a second aerial some how, though that is going to be very difficult.

If over the next few days I get break up without the splitter I will jump to step 4. b)

Does that sound like a sensible course of action?
 
Personally I think separate aerials is more sensible than an amplifier if only two feeds are required. When you look at the cost of a decent amp (a cheap and nasty really won't be worth having) and the electric it will use over the years, a good quality high-gain aerial is probably cheaper.
 
I disagree. The capital and installation cost of another aerial (even if he had space to put it) is going to be more than that of a masthead amp. and electricity.
My back of a fag packet calculation for one these:
https://www.blake-uk.com/masthead-a...psu-ampifier_with_propsu11f_power_supply_unit
gives purchase and 20 years running costs for about £40.
This is what I would recommend that the OP gets, if he needs an amp. If he doesn't, then he can just keep his splitter. He might even be able to get away without buying the PSU if he already has an appropriate device that will power the amp. (most tellies and PVR boxes will) and save another £10 or so.
 
Ezra Pound said:
Introducing the splitter is reducing your signal by half, this is not a problem if you are next door to the transmitter, but at nearly 30 miles away you can't afford the loss
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You don't know categorically whether he can afford the loss or not. Figures provided so far indicate that he can afford the loss.
 
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