TV Reception

[idiott]

I live in an area where TV reception is difficult so the houses have very tall outdoor Ariel's. My Ariel lead comes in through the bedroom window and with the aid of adaptors and enhancers I have connections to 4 TVs. in the bedrooms (The reception is perfect)

For the 5th TV, the Ariel lead continues from the window on the outside wall and enters the living room to the 5th TV. However, I keep getting distortions on some channels. I have unplugged the other sets leaving just the 5th plugged in but I still get distortions Is it because the cable is slightly longer (only about 15 feet)

Can someone please advise.

 

[Lucid]

Presuming that you've done a "First time/Factory default" reinstallation rather than just a simple retune, then yes, cable length can make a difference. It depends on the quality of the cable. It can also be a case that one or more cables isn't terminated correctly or has a break in the outer sheath so that water has got inside. There could also be a difference in the comparative sensitivity of the TV tuners that's contributing to the issue.

Do the simple stuff first. Check the way the plugs are terminated. Make sure there's no little filaments of the braid shield touching the central core. Look for kinks and sharp bends in the coax cable.

For a cable length of 15ft to make a significant difference the cable would have to be quite poor - e.g. the sort of quality you get in those DIY TV extension kits from B&Q/Maplin/Argos - and the signal itself would have to be quite weak. The combination of the two things would be enough to make some of the weaker channel groups start to break up.

In many cases the underlying reason for the signal break-up is not signal level but signal quality. This is far more important than signal level.

If your TV has a way of showing signal strength and signal quality then you might want to check it on the channels that are causing the issue. It's entirely possible to have lots of signal power (80%+) but have very poor quality of signal. Boosters and amplifiers won't help this. The quality comes from the aerial (correct spelling ). The rest of the system should then be built to maintain that quality.

Simplifying your system might help diagnose where the fault lies. It's one of the things we do in the trade when troubleshooting. Try connecting the feed direct from the aerial down-lead straight to the living room TV. Check the picture on the same channels that have been causing a problem upstairs. If all is okay, swap the connection and route the aerial signal up to the bedroom TV. Check the picture up there. If you're still getting a problem then think about changing the cable for WF100 and some decent aerial plugs.

Beyond the above then you could do with calling an aerial installer. They'll be able to check the signal margin and then fit the correct gear so there's decent quality signal to all TVs.

 

[idiott]

Lucid

Thank you for responding. I will act on your recommendations, I think the cable is fine it was not pre packaged Its not WF100 as you suggested (I have that on my SKY Satellite) but I did buy it from B&Q but of a reel by the metre (dark brown).

I will test it stage by stage in the next few days as you suggested.

To explain Its a new a (aerial thanks) 2 years old. braced to the chimney on a ten foot pole. Cable comes into the bedroom split to 5 TVS none of which are on together as I am a widower now. All 5 have very good reception when on together.

The 6 TV in the living room is where the problem is. from the junction box in the bedroom the 6th cable travels on the outside of the building into the TV in the living room where I have the problem with some channels breaking up. The connections to the other TVs are all within the building

However, as I said I will try your suggestions and see what happens.
THANK YOU

 

[Sam Gangee]

with the aid of adaptors and enhancers I have connections to 4 TVs.

That's worrying. I've never heard of an "enhancer". Can you be more specific?

Usually you'd use a 4-output masthead amplifier. One output would feed (via a UHF splitter) the two shortest cable runs to the nearest rooms. That gets you 5 feeds with a fairly equal signal balance. The splitter should be positioned as far from the amplifier as practicable.

Amplifiers with more than 4 outputs are available but are needed only if the above method is unsuitable.

As Lucid mentioned, make sure that all the cable runs use double-screened cable. The old fashioned "low loss TV cable" is unsuitable for digital Freeview.
See http://www.satcure.co.uk/tech/cable.htm

 

[idiott]

Hello Sam

I guess I mean amplifier.

I think I will buy WF 100 and take it step by step.

Thank you for you suggestions I will also I look up eBay for VHS converters

 

[Sam Gangee]

you suggestions I will also I look up eBay for VHS converters

Converters?
Ebay?

 

[Lucid]

I think the cable is fine it was not pre packaged Its not WF100 as you suggested (I have that on my SKY Satellite) but I did buy it from B&Q but of a reel by the metre (dark brown).

From your description, my best guess would be that you have bought Tower TV & Radio coaxial cable. That's marginally better than the the stuff supplied with the moulded on plug ends.... but not much.

I am hoping that the picture describing the design of the cable is incorrect, and that it does have a foil shield as well as the few stands of (probably) aluminium. But in any event the DIY sheds don't stock decent coax. If you have the option to change it out for WF100 then that's a good plan.

To explain Its a new a (aerial thanks) 2 years old. braced to the chimney on a ten foot pole. Cable comes into the bedroom split to 5 TVS none of which are on together as I am a widower now. All 5 have very good reception when on together.

The 6 TV in the living room is where the problem is. from the junction box in the bedroom the 6th cable travels on the outside of the building into the TV in the living room where I have the problem with some channels breaking up. The connections to the other TVs are all within the building

Thanks for the extra information.

From what you have said I have this as a vision of your system layout:

The signal split to feed TVs 5 & 6 is where you've said the issue is. But only affecting TV 6.

So what I'd guess is happening is that the signal is just about okay after the two way splitter and there's enough quality to drive TV 5 via the short coax cable. But when you've added 15 or so feet of iffy B&Q cable it's the straw that broke the camels back. The quality is bumping along the very bottom of the acceptable range. The weaker channel groups are starting to break up.

Changing the cable from the splitter to TV 6 will claw back maybe 1 or 2 dB if that Tower cable is really bad. You should also check through the rest of the connections in the chain from aerial through all the splitters. Multiple adapters and cable joiners won't be helping your cause.

 

[Sam Gangee]

That's pretty much what I described except I would use a proper low-noise masthead amplifier (not a "signal distribution booster"), a fully screened metal splitter (not plastic) and the two split cables should feed the shortest runs, using the best cable.

Masthead Amps with up to 8 outputs are available:
http://www.satcure.co.uk/accs/page11c.htm#8WAYAMP

 

[idiott]

Hello Lucid,

Thank you, you have been very kind and helpful. I have managed to sort the problem out thanks to your advice.

Since I have been widower and live alone and have confined myself to rear room of my house where I have SKY I rarely visit the sitting room. However, of late I have become adventurous. From time to time I tend to forget things that I have done in the past. Taking your advice I made a direct connection Aerial to TV. No improvement. Then I decided to look at the connections behind the TV. I had put a cheap booster there some years ago I forgeot. I changed it with a new one and the reception is brilliant I say 90%. So in the next week I will buy a WF 100 cable the present one is the Tower Coaxial.

Thank you once again. Now to sort the dam VHS To DVD out

 

[Sam Gangee]

Good that it's working but, for the record, a booster by the TV is inappropriate. The signal should always be boosted at the input end of a long cable - not at the output end where the signal is weaker. Have you tried with this booster removed/bypassed?

 

[idiott]

Hello Sam

Thank you

I have removed the Booster and the picture is still good. I ordered a length of WF100 cable from Aerial Sat

Thank you for your help

 

[Sam Gangee]

That's good news.
How to fit plugs correctly: http://www.satcure.co.uk/tech/fconn.htm

 

[Lucid]

I don't doubt you. Just saying I've never had an issue in 7 odd years of professional aerial installing and 25 years before that doing incidental work.

Also, VHF.... What, for broadcast TV? I know 405 line was around in a couple of TV regions for a lot longer than most people realise, but surely that wouldn't have been a problem for the bulk of the UK for the last couple of decades? And wouldn't that be down as much to the poorer quality shielding and braid coverage of "low loss" TV coax? Or are you referring to some use of VHF outside of the realms of broadcast TV reception?

 

[winston1]

I don't doubt you. Just saying I've never had an issue in 7 odd years of professional aerial installing and 25 years before that doing incidental work.

Also, VHF.... What, for broadcast TV? I know 405 line was around in a couple of TV regions for a lot longer than most people realise, but surely that wouldn't have been a problem for the bulk of the UK for the last couple of decades? And wouldn't that be down as much to the poorer quality shielding and braid coverage of "low loss" TV coax? Or are you referring to some use of VHF outside of the realms of broadcast TV reception?

VHF is/was used on RF distribution systems, and is still used for broadcast in many countries. I worked on a large distribution system for several years and instantly recognised patterning, especially on band 1 channels when the screen of the aerial plug was not making due to the reason stated. Nothing to do with poorer quality cables. More recently, on holiday in Vietnam, my hotel TV exhibited this same symptom. Other half wanted to know why I was taking the aerial plug to bits on hotel TV. Explained that I wanted to watch it interference free. Had to bodge it a bit as I had no tools but I managed it.

 

[Lucid]

Vietnam... fine. Other countries.... fine. But the UK?.......now... today ...in 2014....not 20 years ago?????????????