Author Topic: Fitting a TV aerial (Read 1984 times)

Hush · « **on:** March 03, 2011, 01:24:23 AM »

OK I've fitted a few in my time but never taken too much notice of the wiring or it's been already wired up or was so blatantly obvious that I didn't have to think about it.
Anyhow I turned part of my garage into a home gym area and as the daily 15 minutes on the treadmill is pretty boring without some form of stimulation I put a TV out there.
In trying to improve the signal I purchased a new aerial and even though there are only two wires I still can't figure out where they go?

Basic coaxial wiring with the inner copper wire and the outer earth wire, but where the heck do they go? I feel soooo dumb, at the moment I have the earth wire attached to the centre of the aerial and the inner wire attached to the loop section, result...worse than rabbit ear aerial I had before! There are 3 wing nuts on threaded bolts where the 2 wires could go, 2 of these are attached to the aluminium aerial "loop" the other one is part of the main bar that runs the length of the aerial!
To make matters worse, my older brother is probably New Zealand's most eminent expert on aerial technology so I ain't asking him.

demon78 · « **Reply #1 on:** March 03, 2011, 03:52:54 AM »

Sounds to me like the antenna connections are 300 ohm and need to be run to the TV as 300 ohm or you need a transition between 300 ohm and the coax, this coming from an old TV tech and my information may be at least 40 years out of date also different countries any how check out the 300 ohm thing (flat cable with 2 wires one on either side)
Bill the demon.

wardenerd · « **Reply #2 on:** March 03, 2011, 06:50:11 AM »

don't they have satellite tv in NZ?

333 · « **Reply #3 on:** March 03, 2011, 06:58:24 AM »

I'm wondering how old that set must be if it doesn't have a 75 ohm "F" connector.

But if you have 3 terminals, not only do you need a matching balun to go from 75 ohm to 300 ohm, you will need a splitter. The terminals are probably marked with something like "UHF", "VHF", and "Common" or "Ground".

Gordon · « **Reply #4 on:** March 03, 2011, 08:07:55 AM »

Is this what you guys are talking about? Those things we used to use to connect a VCR or video game system to an old TV that didn't have a coax input?

scottly · « **Reply #5 on:** March 03, 2011, 10:12:14 AM »

Here's a pic of an antenna with a matching transformer. The third connection to the main bar is probably for an earth ground, for lightning protection.

Hush · « **Reply #6 on:** March 03, 2011, 10:29:41 AM »

OK I get the ohm thing but what I need to know is do the two wires attach to either end of the loop (which does not make sense to me) or one to the end of the loop and one to the main part of the aerial pole which appears to be the earth?

Gordon · « **Reply #7 on:** March 03, 2011, 10:32:15 AM »

Hey Hush, how's about a cheap DVD player for your garage TV?

Hush · « **Reply #8 on:** March 03, 2011, 10:39:15 AM »

I got one of those, just want better picture on me TV.

Invested in a new 42 inch flat screen this week as old main lounge TV was about to die and the whole country is going Digital as of September 2012.
My step daughter scored me all 3 seasons of "Sons of Anarchy" so big screen came just in time.

dave500 · « **Reply #9 on:** March 03, 2011, 12:01:23 PM »

the outer braid goes under the saddle and the conductor goes into the little grub screw hole,havent seen 300 flat cable for years here,maybe see your local tandy or dick smith shop?one of the screws will be vhf and one is for uhf which is the one youll need i think,do you guys have digital transmission yet?also make sure you have the polarization correct ,look at the other ones on nearby homes,are they vertical like yours is shown or horizontal?

TwoTired · « **Reply #10 on:** March 03, 2011, 12:52:28 PM »

Quote from: Hush on March 03, 2011, 10:29:41 AM

OK I get the ohm thing but what I need to know is do the two wires attach to either end of the loop (which does not make sense to me) or one to the end of the loop and one to the main part of the aerial pole which appears to be the earth?

If you have a loop antenna on your TV, it attaches to it at some point. I'm going to guess that it is two screw terminals. If so, that is a 300 ohm connection.
You will have to remove the loop antenna and use those screw terminals and attach you new antenna to it there.

What you haven't told us is what cabling the antenna came with, or the cable attachment method that the new antenna uses. In the states there are generally two options. 300 ohm or 75 ohm. 75 ohm uses coaxial cable. 300 ohm uses flat twin wire.

If the antenna you bought has two screw terminals, it is 300 ohm also, in which case you need a twin wire length to connect TV to Antenna. Anytime you transition between twin wire and coaxial, you need a balun (which stands for BALanced to UNbalanced) Twin wire is balanced, Coax is unbalanced. The balun does the impedance matching 75 Ohm to 300 Ohm and vice versa.

I don't think I can help more until I know more about the devices you are trying to interconnect and their connection point description. But, you cannot add an antenna to your loop (and expect good results), you must replace it at its connection point.

Cheers,

scottly · « **Reply #11 on:** March 03, 2011, 01:36:43 PM »

Quote from: Hush on March 03, 2011, 10:29:41 AM

OK I get the ohm thing but what I need to know is do the two wires attach to either end of the loop (which does not make sense to me) or one to the end of the loop and one to the main part of the aerial pole which appears to be the earth?

Yes, the 2 wires from the matching transformer attach to either end of the loop. Also, as dave said, your antenna appears to be rotated, at least compared with the US standard. Here's a pic showing the connection to an antenna with a loop as the active element...

Hush · « **Reply #12 on:** March 03, 2011, 09:26:12 PM »

All our TV aerials are set like that with the spikes vertical, I noticed the US ones all seem to be horizontal.
I think I'm getting the picture (well soon will be) I didn't quite understand the relationship between the coaxial cable and the aerial.
I always think 12 volts and apply it like I would to a car/bike, but if the exterior coaxial mesh is another actual aerial wire (not an earth) then yes I have wired it wrong, I'll also get a balun as I think the aerial I bought was for strip cabling not coaxial.
Jezz I'm dumb.

Cheers guys, you have come through when neither Wikipedia or Google could.

Really? · « **Reply #13 on:** March 03, 2011, 09:35:54 PM »

Hah, this thread is like a forum I know that is about old bikes!

scottly · « **Reply #14 on:** March 03, 2011, 09:46:53 PM »

Hey, I cut my eye teeth helping my dad install antennas back in the '60s, before cable reached our town.
Funny story my dad told me; happened when I was still in diapers..
He was installing an antenna on a roof, with an overly "helpful" new guy. They had erected the mast, with the antenna attached, and temporarily tied one of the guy-wires to a vise mounted to the work truck below. At some point, they needed some hardware from the shop, and the eager-beaver dashed down the ladder, jumped into the truck, and sped off, yanking the mast, antenna, and almost my dad off the roof...

dave500 · « **Reply #15 on:** March 03, 2011, 10:49:00 PM »

we have both horizontal and vertical polarization here on the gold coast,two different transmitters,so depending where you are you use the tower that suits you best,your unit looks like an fm/vhf one,if you ring your local tv guy and ask what signal you should be recieving,you might be better off with a uhf dedicated yagi type,or a phased array if ghosting is a problem,digital shouldnt have ghosting.

Hush · « **Reply #16 on:** March 04, 2011, 01:01:05 AM »

Aw shuddup Tipper

faux fiddy · « **Reply #17 on:** March 04, 2011, 01:31:59 AM »

Quote from: Hush on March 03, 2011, 10:39:15 AM

I got one of those, just want better picture on me TV.
Invested in a new 42 inch flat screen this week as old main lounge TV was about to die and the whole country is going Digital as of September 2012.
My step daughter scored me all 3 seasons of "Sons of Anarchy" so big screen came just in time.

Friends had a new digital antenna to replace their old thing when it was mandated in the US a couple years ago. Reception went to sh8 with digital antenna. The joke we made was there's nothing the Gov't does that doesn't FU the free stuff.

dave500 · « **Reply #18 on:** March 04, 2011, 01:48:19 AM »

you got that fiddy,with digital its all or nothing,or a pixelated eye blowing monster!,you must use a premium antenna,good RG6 cable,the old analouge was more forgiving with dodgy connections and such,the old coat hanger out the window days are over,a proper re-orientation of the antenna will do wonders,heavy rain affects digital more than analouge.

faux fiddy · « **Reply #19 on:** March 04, 2011, 02:28:25 AM »

Quote from: dave500 on March 04, 2011, 01:48:19 AM

you got that fiddy,with digital its all or nothing,or a pixelated eye blowing monster!,you must use a premium antenna,good RG6 cable,the old analouge was more forgiving with dodgy connections and such,the old coat hanger out the window days are over,a proper re-orientation of the antenna will do wonders,heavy rain affects digital more than analouge.

Yeah, they eventually added a some cable and raised the antenna to the top of the roof, but like you say, no more twiddling with rabbit ears ease.

Still some stations they can't catch as well as with analogue.

Spanner 1 · « **Reply #20 on:** March 04, 2011, 01:46:59 PM »

Back in the 'olden days' you could receive the elusive BBC in coastal areas around Dublin by installing a high aerial on your roof to pickup the transmitter outside Belfast N.Ireland.
It was low band VHF and the 4 element aerial was about 8ft x 8ft !! If you wanted to see 'Top Of The Pops' at 7pm, you turned on the T.V. at 6pm to allow it to 'warm-up' !! ( Tubes !! )''
Hopefully the pic. would sync.and stop 'rolling' before your show started .... kids these days have it sooo easy

Hush · « **Reply #21 on:** March 04, 2011, 10:25:38 PM »

OK my big brother has finally got back to me, he was trapped in Christchurch when the earthquake struck and norrowly avoided getting flattened when the building he was in collapsed.
A balun (as suggested by a few on here) is the answer to my woes...thanks all for the input.

demon78 · « **Reply #22 on:** March 05, 2011, 05:37:25 AM »

Spanner that's about the time I was fixing TV's, ah tubes, I remember if you got to close to the regulator it would burn a hole in and out, little black dot in your hand never did find the out and the high voltage would zap you like a lightning strike, ah the good old days then Zenith introduced a new model with transistors and the fun began, occasionally the regulator circuit would fail in a certain way and high voltage would go past normal 27.5 KV to around 54+ Kilo Volts at which point it would arc through the picture tube, pop it and come to a smoking stop, one of our customers had it happen to him and his family, said it was impressive as hell all of a sudden the picture got really bright the was a loud pop and fire, smoke blew the breaker etc he was pissed, got watch his new TV for a couple of hours and had to fight with Zenith for a replacement.
Bill the demon.

Spanner 1 · « **Reply #23 on:** March 05, 2011, 08:40:22 AM »

Ah Bill !..... remember when the 100uf capacitor @ the EL84 audio output tube ( the same tube that's used in the famous VOX AC30 guitar amps ) would blow-up and rain down conductive contents all over the circuit board ?.... looked like a day-old chick exploded in the back of the T.V.

... took ages to pick up every tiny piece to avoid shorts on the board.. AND do it in a customers house while the whole family sat around waiting for the TV to be fixed, having already watched TV for 2 days without any sound

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Author Topic: Fitting a TV aerial (Read 1984 times)