Do I need a better antenna?

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MikeAqua

7611 posts

Uber Geek

#144134 8-May-2014 12:57

I am using this entry level UHF antenna.

http://www.dicksmith.co.nz/antennas/dick-smith-hd-uhf-outdoor-antenna-pack-dsnz-l4735

DSE told me it would be OK for our location (The Wood, Nelson). But If the weather is poor - rain or even a lot of cloud on Mt Campbell where the transmitter is, the picture breaks up. This is worse on Choice, Prime, Maori etc.

Our house is about 40km horizontal distance from the Freeview UHF transmitter, with about 1,200m altitude difference.

The current antenna has clear line of sight and it pointing right at the transmitter tower (Mt Campbell) which I can see on good day. The rotation of the antenna is correct. I have quality RG6 cable and good F-Type crimped, sealed connections.

Advice appreciated. Specifically should I try a different antenna and what sort?

Mike

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3344 posts

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Vocus

#1038983 8-May-2014 13:15

You may need a masthead amplifier, from a bit of research there aren't many antennae out there with more gain than the one you've got (assuming the figure is accurate of course).

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Brunzy

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#1039037 8-May-2014 14:20

Better to try & see if you can find a better location on your roof first.
If you have someone that can help , bring up the diagnostics on the set , ie S & Q , first of all move the aerial up/down the mast,
if not enough improvement " take it for a walk on the roof " Perpendicular to the Tx is where you would normally find the greatest variation.
You would probably need to make up an extension cable.

turb

863 posts

Ultimate Geek

#1039070 8-May-2014 14:23

I'd say get a bloke in.

You could spend money fiddling about, and still have the picture break up. Then you'd be back to square one, still not knowing whether you have the alignment absolutely right etc.

The bloke will be more money up front, but at least you know it isn't wasted money, and you know the picture is as good as it possibly can be.

Interests: HTPC, Web App authoring.

turb

863 posts

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#1039072 8-May-2014 14:23

Interests: HTPC, Web App authoring.

turb

863 posts

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#1039086 8-May-2014 14:25

If it's worth saying once, it's worth saying twice!

Or three times @Brunzy

Interests: HTPC, Web App authoring.

Bung

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#1039133 8-May-2014 14:51

ubergeeknz: You may need a masthead amplifier, from a bit of research there aren't many antennae out there with more gain than the one you've got (assuming the figure is accurate of course).

The DSE aerial "Antenna gain: up to 14dB" yet it is recommended for "broadcasts in prime areas". DSE don't seem very confident. I have a similar looking aerial of unknown brand that has no problems getting Wharite Peak near Palmerston North from 60km away

A Freeview Shop 91 element aerial for fringe areas is rated 14-16dB.

B1GGLZ

1961 posts

Uber Geek

#1039181 8-May-2014 15:34

Judging from the Freeview coverage maps you should get a solid signal from Mt Campbell or Kaka Hill.
I would seriously inspect your antenna system for bad joints or water ingress before going for a new antenna.
You say the antenna rotation is correct. I presume you mean polarity is vertical?

Sideface

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#1039183 8-May-2014 15:35

The DSE aerial is entry-level and is recommended for "broadcasts in prime areas".
I don't think that the OP is in a "prime area".
Get a man in before wasting any more money.

Sideface

Apsattv

2138 posts

Uber Geek

#1040464 9-May-2014 02:51

Why are you using MT Campbell? surely KAKA Hill is much much closer and would have a better signal?

Can you confirm in your tuner settings, which frequencys you are actually getting. CH numbers.

It could be that you have actually tuned into the KAKA Hill transmitter off the back or side of your antenna.

Are you also getting Mainland tv on Channel 26 or 27?

MikeAqua

7611 posts

Uber Geek

#1040711 9-May-2014 10:49

Kaka hill is closer but our house is up against the range of hills Kaka is part of and it is round a bluff in that range so we are obscured from it. If you look at the coverage maps you will see a few little dead spots close to the hills where there is no coverage from Kaka Hill. We are in one of those pockets - right below "The Wood" on the freeview coverage map.

No Mainland Channels. According to mainland they broadcast from Observatory Hill, which is in a different direction, to Mt Campbell (edit: Observatory Hill is also horizontal polarity, where as my antenna is set to vertical for Mt Campbell).

I'll check the frequencies tonight.

Mike

B1GGLZ

1961 posts

Uber Geek

#1040729 9-May-2014 11:17

Have you removed any old VHF or other antennae that may be close to your UHF?

MikeAqua

7611 posts

Uber Geek

#1040764 9-May-2014 12:30

B1GGLZ: Have you removed any old VHF or other antennae that may be close to your UHF?

Yes I removed it when I installed the UHF antenna. Cut the old cable back to very near roof level. No other antennae on our roof and we are above all our neighbours.

The antenna is on the ridge line. I'm 6'1" and it's at chest height when I stand next to it. As per earlier post clear line of sight to transmitter verified with a high magnification rifle scope and clear day last week.

I whipped home at lunch time and check the TV info.

I am picking up UHF channels 31, 37 & 39 .

The TV (Sony Bravia) shows the signal as 'strong' and displays a green 100% signal bar for TVNZ and TV3 channels. For Choice, Prime et al it is 'good', yellow and a 75% signal bar. So the signal getting to the TV is actually pretty good.

I've been doing some reading and it seems quite a few people have intermittent trouble with Mt Campbell signal breaking up. It's possible that this is just how it is and it may be the relay of the signal to Mt Campbell that is the problem.

Mike

B1GGLZ

1961 posts

Uber Geek

#1040797 9-May-2014 13:05

MikeAqua:

I am picking up UHF channels 31, 37 & 39 .

The TV (Sony Bravia) shows the signal as 'strong' and displays a green 100% signal bar for TVNZ and TV3 channels. For Choice, Prime et al it is 'good', yellow and a 75% signal bar. So the signal getting to the TV is actually pretty good.

I've been doing some reading and it seems quite a few people have intermittent trouble with Mt Campbell signal breaking up. It's possible that this is just how it is and it may be the relay of the signal to Mt Campbell that is the problem.

OK
According to this chart you should be getting 33, 35, 37.
http://www.rsm.govt.nz/cms/tools-and-services/publications/broadcasting/digital-television-channel-usage
I'd try manual tuning these channels.
Ch31 is Igloo which your TV shouldn't receive as it's DVB-T2. It's tuner is not DVB-T2 capable. My Sony doesn't find Igloo.
If all else fails I'd suggest try another antenna.
Some good info here
http://www.freeviewshop.co.nz/information/technical/aerial-guide-i-49.html

Jaxson

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#1040808 9-May-2014 13:13

MikeAqua:

The rotation of the antenna is correct. I have quality RG6 cable and good F-Type crimped, sealed connections.

Who did the crimping, and what type did they use?

It only takes a small mistake to make a huge difference to the signal degradation.

Does the cable run anywhere else in the building, to a splitter perhaps or to multiple room outlets etc?

Ideally you want to strip it right back to a single run from the aerial to the TV and then start re introducing side branches etc from there.

MikeAqua

7611 posts

Uber Geek

#1040934 9-May-2014 16:57

Oops, I was looking at the wrong piece of paper in my earlier post.

The programme sorting function on my TV shows the following channels and services:

33: TV3, FOUR, C4, Al Jazzera, The Shopping Channel, Te Reo,
41: ONE, 2, ONE+1, 2+1
47: Maori, Prime, Trackside, Choice TV, Sommet Sports, TVSN Shopping, First Light

Manual Tuning doesn't find anything at all 35 or 37. My manual tuning function is limited. I can't force it to a particular channel. All I can do is enter a start channel and a search direction.

Mike

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