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What is the best way to concoct a makeshift TV. antenna?


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Old 23-04-2006, 16:53
d_w321
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Alas I have no wire coat hangers

using some co-axial cable, and a connector, I've plugged into the tv. and at the other end of the cable I've made a loop 5" diameter.
I played around with it, and put it in the best position. 5/10 - good sound, fuzzy picture. help!



NB I'm waiting for my landlord to complete the new aerial on the roof.

The supermarkets are closed, and i'm missing the snooker

Times are hard, so the pub is out of the question, a botch needed

Last edited by d_w321 : 23-04-2006 at 17:47.
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Old 23-04-2006, 17:02
SimonBlackham
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Some supermarkets have simple set-top aerials for less than 5 that are actually quite good.

Go for one that looks like a plastic covered Yagi or log periodic...

| | | |
| | | |

or
./\_/\_/\
/..\/..\/

with the elements rotatable to horizontal/vertical as required for your transmitter.

See http://www.wolfbane.com/cgi-bin/tvd.exe? for details.
or similar
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Old 23-04-2006, 17:37
kev
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Originally Posted by d_w321
Alas I have no wire coat hangers

using some co-axial cable, and a connector, I've plugged into the tv. and at the other end of the cable I've made a loop 5" diameter.
I played around with it, and put it in the best position. 5/10 - good sound, fuzzy picture. help!



NB I'm waiting for my landlord to complete the new aerial on the roof.

The supermarkets are closed, and i'm missing the snooker

Times are hard, a botch needed
Well it sounds like you've connected it to the TV, you just need to faff with it to get better reception. My old housemates used to use a fork as a TV aerial, but then again they did live next door to The Wrekin transmitter back home.

Try removing the plastic insulation from the cable as it;s designed to prevent any unwanted (including the wanted in your case) signals in.

Is there any remnants of an aerial on the roof? If so try using that. Or give up and go down the pub and watch it there
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Old 23-04-2006, 18:28
Barry.Williams
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Originally Posted by d_w321
Alas I have no wire coat hangers

using some co-axial cable, and a connector, I've plugged into the tv. and at the other end of the cable I've made a loop 5" diameter.
I played around with it, and put it in the best position. 5/10 - good sound, fuzzy picture. help!



NB I'm waiting for my landlord to complete the new aerial on the roof.

The supermarkets are closed, and i'm missing the snooker

Times are hard, so the pub is out of the question, a botch needed

Personally I would not bother trying to make one. There are plenty of daft ideas posted on here such as using coathangers and other nonsense. If you have a very strong signal it might work if not it will not.

Basically an aerial needs to have the elements cut to half or quarter of the wavelength. Typically a Yagi will have sevral horisontal elements and a reflector. You need to select the feed point to the arial to match the cable impedence. A mismatch here will give you a high SWR resulting in poor gain. You could try making a horizontal dipole out of wire. The tricky bit will be matching it to the coax as at the cente the impedence will be something like 300R and not the 75R of the coax and the aerial import to your TV.
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Old 23-04-2006, 18:32
Barry.Williams
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Originally Posted by kev
Well it sounds like you've connected it to the TV, you just need to faff with it to get better reception. My old housemates used to use a fork as a TV aerial, but then again they did live next door to The Wrekin transmitter back home.

Try removing the plastic insulation from the cable as it;s designed to prevent any unwanted (including the wanted in your case) signals in.

Is there any remnants of an aerial on the roof? If so try using that. Or give up and go down the pub and watch it there

Rmoving the black insulation ? Why ? It does not carry the signal. It serves to protect the cable and to provide. Removing it may also alter the impdence of the cable.
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Old 23-04-2006, 18:41
billybob
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use a metal coathanger, it must be benchmarked of course to recive freeview
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Old 23-04-2006, 18:42
alunjenkins
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best aerial I ever made was made out of some coax cable linked to a wire paper tray, did it so as to watch the world cup in school lol.
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Old 23-04-2006, 21:14
d_w321
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It's hard to tell which ball is which!
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Old 23-04-2006, 21:51
Chris6000
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Originally Posted by alunjenkins
best aerial I ever made was made out of some coax cable linked to a wire paper tray, did it so as to watch the world cup in school lol.
I remember i made a aerial out of scissors in school when world cup was on and worked pritty good but the hertford relay was next door
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Old 23-04-2006, 23:53
Ray Cathode
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Go down to B&Q or similar and buy an aerial and stick it out of the window in the general direction.
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Old 24-04-2006, 09:12
Captain Cod
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Maplins do a servicable one for about a fiver. If it doesn't work, you can use it as a coathanger. Well, you can hang ties on it.
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Old 24-04-2006, 13:47
jay_2k2
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If it was for analogue I'd say use the wire tray out of the grill but for digital no idea, unless next doors cable is close and you wait until after dark lol
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Old 24-04-2006, 15:52
David (2)
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Argo's do cheap proper size wideband aerial for 8.99 (its the gold one). Fine if you live in a strong signal zone - and a better option than a portable table top aerial.

Dave
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Old 24-04-2006, 17:26
kev
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Originally Posted by Barry.Williams
Rmoving the black insulation ? Why ? It does not carry the signal. It serves to protect the cable and to provide. Removing it may also alter the impdence of the cable.
It is also designed (unless its the cheapest crap) to block out unwanted frequencies - such as band IV and V TV! Removing the cover would theoretically allow more signal in.

Anyways, the shops are now open so get down to poundland and spend a quid and your sorted until the proper antenna is installed (if it's immienent) or do what I did and get a log periodic from Maplin and wire that up - in the loft if you can, or as i've done on top of the wardrobe.
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Old 24-04-2006, 22:51
Barry.Williams
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Originally Posted by kev
It is also designed (unless its the cheapest crap) to block out unwanted frequencies - such as band IV and V TV! Removing the cover would theoretically allow more signal in.

Anyways, the shops are now open so get down to poundland and spend a quid and your sorted until the proper antenna is installed (if it's immienent) or do what I did and get a log periodic from Maplin and wire that up - in the loft if you can, or as i've done on top of the wardrobe.
The insulation does not do that. Its the outer screen that helps protect the feeder cable from noise pickup. Removing the outer sheath will also allow mositure to get into the foam insulation which will not do a lot for the signal.
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Old 24-04-2006, 23:06
pioneer_dtr
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Originally Posted by Captain Cod
Maplins do a servicable one for about a fiver. If it doesn't work, you can use it as a coathanger
you lot are having a laugh

Originally Posted by jay_2k2
If it was for analogue I'd say use the wire tray out of the grill
do you need to remove the sausages first?
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Old 25-04-2006, 06:54
Barry.Williams
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Originally Posted by pioneer_dtr
you lot are having a laugh

do you need to remove the sausages first?
No but you have to pre heat it to 250C first to get optimum reception from it.
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Old 25-04-2006, 13:38
terrytoye
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I know for some, the mysteries of wireless communication may seem like a black art, but for me, having been involved with communication engineering for over 30 years, it is not.

Coaxial cable is, (even though it doesn't look it), waveguide.
The only difference is that there's a centre conductor in coax but none in waveguide. (WG is used to connect high performance microwave antennae to their transceivers).

So, as has been mentioned, if you don't terminate the coax correctly it wont work correctly. It will not be 'balanced' along its length and will pick up all sorts of signals from anywhere. ie interference from your neighbors' 'crap' electrical equipment.
You must connect, either a proper antenna or open up the coax so that the inner and outer are at right angles to the feed and of the correct length to match the frequency you wish to receive. This simple dipole is not very good for TV as each TV group covers such a wide frequency. It is necessary to fit some kind of antenna which is designed to work over a greater bandwidth.
There is no doubt that using good quality coax (preferably CT100 Sat coax), and a reasonable antenna, will give least problems.
Remember, in fringe areas you will often experience 'ghosting'. This can arise from the same transmission arriving later by a reflected route. Often only one channel in a group is affected. This is 'supposed' not to be such a problem with DTT. Anyway, large, single group antennae are often good for reducing these problems as their acceptance angle is much less.

I live at the bottom of a 'valley', in Blandford in Dorset. I have to get my DTT freeview from the Isle of Wight. It's a long way and the signal is way down below what will normally work. Most near me cannot receive it. I can. Adopt the principle of getting the best signal into the antenna and ONLY then putting an amplifier on to the system as close as possible to the antenna as you can.

Enough for now,

Terry Toye
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Old 25-04-2006, 18:17
Geordie_Cy
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Originally Posted by d_w321
Alas I have no wire coat hangers

using some co-axial cable, and a connector, I've plugged into the tv. and at the other end of the cable I've made a loop 5" diameter.

Because a 5" loop is resonant at which freq?
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Old 25-04-2006, 18:45
Eye2006
 
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Originally Posted by d_w321
Alas I have no wire coat hangers

using some co-axial cable, and a connector, I've plugged into the tv. and at the other end of the cable I've made a loop 5" diameter.
I played around with it, and put it in the best position. 5/10 - good sound, fuzzy picture. help!



NB I'm waiting for my landlord to complete the new aerial on the roof.

The supermarkets are closed, and i'm missing the snooker

Times are hard, so the pub is out of the question, a botch needed
Yet again someone else has no location.On this occasion I will assume you are in bikini Bottom.

Right go down to Argos and get a standard Digital ariel.Problem is solved.If not then get a powerful booster.Alternatively use a fork and jam it in the ariel hole.That should do something.
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Old 25-04-2006, 20:45
Redcoat
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I've never tried this myself, but in theory it could work. If you only have the coax-cable, strip the insulation. How much of this will depend on what group of channels there are that you want to receive - try around 13cm as a good compromise (Group A will require a little more, Group C/D a little less). Be careful not to cut the braid, which are the masses of thin wires underneath the insulation.

Once the insulation is stripped, take the braid and straighten it out. Cut the plastic or foam covering below it (not a straight cut!) to then expose the inner conductor.

Now make sure that the inner conductor and braid are 180 degrees apart and that they don't touch each other (important!)

You now very much have a DIY dipole! use a bit of tape, blu-tack or something to either hold it to a wall or straight object.
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Old 25-04-2006, 21:35
Captain Cod
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Originally Posted by Barry.Williams
No but you have to pre heat it to 250C first to get optimum reception from it.
Well only partly true. You'll have no bother getting Red Hot TV. But if you want to watch Frost, on ITV, you'll need to turn the gas down.
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Old 25-04-2006, 21:44
Adam McGuinness
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Originally Posted by Barry.Williams
No but you have to pre heat it to 250C first to get optimum reception from it.
No wonder my signal keeps dropping... Mine only goes up to 220C
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