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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Alarms, Phones, Aerials, CCTV & Datacomms >> is my tv ariel knackered ? https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1320946970 Message started by dj-paul-c on Nov 10^th, 2011, 5:42pm

Title: is my tv ariel knackered ?
Post by dj-paul-c on Nov 10^th, 2011, 5:42pm

i got a tv for the upstairs bedroom,living room tv runs from telewest

i had my tv running in the bedroom for a few days with no problems, yesterday i thought id try and make it better so -

existing was-- tv ariel on roof cabled into attic "taped" joint then 15 meters of coax (i fitted a plug when i bought the tv -and droped cable through ceiling)

i tried to --fit new tv coax point and box at the "taped joint" in attic, plugged in an extension lead from tv point down to tv approx 3 meters in length,

after that there was no signal,i retuned hardly picked up many chanels and tv screen looked like lots of pixels

i got my basic continuity tester and tested between the centre pin and the outer and i was getting a reading ?? of 4 ohm, a very near dead short ?? surley this shouldnt be a correct reading ??

it did rain the other day and also the ariel has been in for many years

any help appreciated
do i need a new ariel

i checked on the satcure site but cant see much regarding testing a tv ariel
my ariel has the connection box on top,mebae theres water in it ?? or have i blown something in the ariel after cutting the wire

Title: Re: is my tv ariel knackered ?
Post by londonman on Nov 10^th, 2011, 6:48pm

Repeat after me...

If it ain't bust, don't fix it!

I would look at the only change you've made to the system...if I follow you correctly. Namely your coax socket and plug. Chances are you've got a whisker of earth shorting to the inner.

Title: Re: is my tv ariel knackered ?
Post by dj-paul-c on Nov 10^th, 2011, 7:16pm

londonman wrote on Nov 10^th, 2011, 6:48pm:

Repeat after me...

If it ain't bust, don't fix it!

.

i was thinking that last night after i "fixed" it ::)

i disconected the cable from the tv point and tested the cable on its own after re stripping the end and still got a reading from centre core to the outer screen ?

i think ive properly fooixed :'(

Title: Re: is my tv ariel knackered ?
Post by scotspark on Nov 10^th, 2011, 8:46pm

at the aerial the 2 cores at joined to the same bit of metal :)

Title: Re: is my tv ariel knackered ?
Post by Lectrician on Nov 11^th, 2011, 7:16am

A standard TV aerial will present a short when tested with a multimeter.

To test properly you need a signal meter whicg measures gain and signal to noise ratio, not a tool that most sparks would fork out on unless they do aerials quite often.

I would double check all your plugs and joints for shorts (whiskers), and remove as many joints as you can. If you need to joint, use two F connectors and a coupler. These make a solid joint rather than a casual one.

Choosing a replacement aerial is not as simple as thinking "bigger the better", if you get an aerial that is too large, you recieve too much signal, and this is worse than too little. Don't neccessarily go by what you have already - it could have been installed incorrectly already. And the same goes for looking at the neighbours! If the street seems to all have the same type/size, then go for it!

Title: Re: is my tv ariel knackered ?
Post by CWatters on Nov 11^th, 2011, 7:48am

Best way to joint a cable is to use two F-Series male connectors on the cable ends and an F-series female to female coupler. However the F-Series male connectors can be a bit fiddly to fit if you've never done one. Plenty of instructions on the web though.

One problem with digital TV is that the picture can appear perfect even when the signal is very marginal. That means a small reduction in quality can push it over the edge and make it appear as if you have introduced a major fault. Some places recommend avoiding face plates totally as they are usually poor quality.

Take a look around this site..

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

Title: Re: is my tv ariel knackered ?
Post by wozzy on Nov 11^th, 2011, 8:26pm

f plugs are a doddle to use, and make a good connection, not sure they work that well on low loss crap though.

I have one of these: http://www.ebay.co.uk/itm/FRINGE-2-1-Satellite-TV-Signal-Meter-Finder-Sat-/190373498738?pt=LH_DefaultDomain_3&hash=item2c53250f72#ht_1841wt_1168

worked fine at my house, where there is crap signal.

Title: Re: is my tv ariel knackered ?
Post by Lectrician on Nov 11^th, 2011, 9:25pm

That type of meter just gives you a "signal" reading - useless really TBH. You could be focused on the incorrect satellite, or picking up interference, and yet the meter would still show a "strong" signal.

I have two meters, one for SAT, which has the most commonly used sat transponders installed (changeable online), and allows you to align your sat to them all.

I also have a digital UHF meter which will give you the signal gain and signal to noise for each 'channel' frequency, with the added benefit of a 'test' button which then compares the two readings to give you a "sh*t" or "ok" reading!

Title: Re: is my tv ariel knackered ?
Post by londonman on Nov 11^th, 2011, 9:46pm

Lectrician wrote on Nov 11^th, 2011, 9:25pm:

Oh the bliss of decent test gear. Many many years ago I was a lecturer at the BBC Engineering Training Centre. What test kit they didn't have, wasn't worth having. Borrow it for the weekend? Not a problem!

Title: Re: is my tv ariel knackered ?
Post by dj-paul-c on Nov 17^th, 2011, 6:31pm

update,

i had tested an ariel at a job i was at a few days after posting this, there was no reading between the cores

(i think it just depends what ariel is installed -like scotspark says)

i changed the extension leads for proper coax -retuned and bingo the tv worked,i may have altered the tuning by accident as well as it gives 3 options ,ie
dtv
dtv + tv
tv

obviously for digital or non digi,but these would depend on what the transmitters kicking out

thanks for the "input" 8-)