UHF aerial recommendation

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dale77

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Topic # 54447 17-Dec-2009 23:38

Hi,

I'm thinking of trying to improve my Freeview HD, PRIME reception (irritating micro-pauses) by getting a new aerial. Which one should I replace my old UHF aerial with?

Any suggestions? I'm thinking the current large UHF aerial is not selective enough on the incoming UHF frequencies, and this is what is causing my signal issues. PRIME is bad, 1,2,3 are 99% fine.

Thanks

Dale

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Reply # 283591 17-Dec-2009 23:41

I have a gizmo, Cant knock it,

I in fact have 2 on my house :) http://www.lincrad.co.nz/pshow.php?category_id=90&sub_cid=87&cat_name=&sub_cat_name=%27Gizmo%27%20%20-digital%20ready-%20%20aerials

Jaxson

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Reply # 283643 18-Dec-2009 09:39

Actually the Gizmo is a compromise to receive UHF and VHF signals. That made it ok for traditional analogue TV where channels were broadcast across both, but digital terrestrial broadcasts are solely UHF, so the Gizmo is no longer the best choice.

Something like this is your best bet:
http://www.dse.co.nz/dse.shop/4b2a96f70394e8f4273fc0a87f3b071e/Product/View/L4735

For optimum results you would want to feed this type of aerial directly to your freeview HD device using quality RG6 Coax and F type crimp/compression fittings. Do not try and feed this into a diplexor with a VHF aerial etc.

rscole86

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Reply # 283645 18-Dec-2009 09:42

Where do you live?
Can you see any transmitters around you? use,http://www.lincrad.co.nz/transmittersites.html to help locate them.
The size of UHF antenna you need will be based on how far you are from a UHF transmitter.

Nimma

91 posts

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Reply # 283789 18-Dec-2009 14:47

Lars at Freeviewshop.co.nz is very helpful and he has a range of UHF specific aerials/brackets/masthead amplifiers etc. I'd probably give him a shout.

Deev8

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Reply # 283824 18-Dec-2009 16:00

dale77: Which one should I replace my old UHF aerial with?

It's not a straightforward issue, and one size certainly doesn't fit all.

Its worthwhile reading through some of the material on this website: Aerials and Television It's a British site, so ignore any information about specific transmitters. However the basics of UHF reception are the same anywhere, and there is lots of good information there.

Spyware

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Reply # 283853 18-Dec-2009 18:10

dale77: Hi,

I'm thinking of trying to improve my Freeview HD, PRIME reception (irritating micro-pauses) by getting a new aerial. Which one should I replace my old UHF aerial with?

Any suggestions? I'm thinking the current large UHF aerial is not selective enough on the incoming UHF frequencies, and this is what is causing my signal issues. PRIME is bad, 1,2,3 are 99% fine.

Thanks

Dale

1,2,3 analog PAL are VHF channels in most of NZ so high chance you don't even have a UHF aerial. Maybe you could describe it, length of elements etc.

EDIT: On second thoughts maybe you are talking about the DVB-T muxes so ignore the above.

Ross

Spark FibreMAX using Mikrotik CCR1009-8G-1S-1S+

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dale77

291 posts

Ultimate Geek

Reply # 283907 18-Dec-2009 21:51

Jaxson: Actually the Gizmo is a compromise to receive UHF and VHF signals. That made it ok for traditional analogue TV where channels were broadcast across both, but digital terrestrial broadcasts are solely UHF, so the Gizmo is no longer the best choice.

That was my thought as well. Unless VHF will be resurrected fro digital transmission later down the track.

dale77

291 posts

Ultimate Geek

Reply # 283908 18-Dec-2009 21:52

rscole86: Where do you live?
Can you see any transmitters around you? use,http://www.lincrad.co.nz/transmittersites.html to help locate them.
The size of UHF antenna you need will be based on how far you are from a UHF transmitter.

I live in South Brighton, Christchurch. 11km from the Sugarloaf transmitter that covers all of Canterbury.

dale77

291 posts

Ultimate Geek

Reply # 283909 18-Dec-2009 22:03

Deev8:It's not a straightforward issue, and one size certainly doesn't fit all.

My needs are for a Freeview HD focussed aerial, which is good at pulling in the signal from Sugarloaf 11km away, while ignoring all other signals, from the analogue UHF retransmitter down at south shore, to the neighbour's arc welding kit...

Aerial will input signal into the HVR2200 tuner in my HTPC.

The dick smith hd uhf kit for $99 might be a goer. Any other recommendations?

dale77

291 posts

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Reply # 283912 18-Dec-2009 22:14

Nimma: Lars at Freeviewshop.co.nz is very helpful and he has a range of UHF specific aerials/brackets/masthead amplifiers etc. I'd probably give him a shout.

Thanks, they have 21, 47 and 91 element UHFs. My current ancient aerial (which was already installed when we moved in over 10 years ago) would be in the 91 element range. The dohickeys hanging off the back of the aerial have recently fallen off. Strangely this doesn't seem to have effected reception at all.

We are only 11km from the massive sugarloaf transmitter, admittedly in a traditionally dubious analogue reception area (behind large trees on the spit).

Spyware

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Reply # 283913 18-Dec-2009 22:19

I would try repointing your current antenna, without a suitable BER measuring device may be difficult to judge result though.

Ross

Spark FibreMAX using Mikrotik CCR1009-8G-1S-1S+

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dale77

291 posts

Ultimate Geek

Reply # 283917 18-Dec-2009 22:38

Spyware: I would try repointing your current antenna, without a suitable BER measuring device may be difficult to judge result though.

I did get a guy out and matters were improved with the current aerial, basically we took an existing VHF aerial out of the loop and ran a new cable direct from the UHF aerial to the HTPC. We also tweaked direction slightly, but this was not done "scientifically" via BER. In my experience the installers are a bit new to the digital terrestrial stuff...

Repointing is not something I want to do often (we have a high peaked roof) and for a number of reasons I think the current large aerial is not selective enough and may be overloading the HTPC tuner with interference signals.

WildBill

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Geek

Reply # 284127 20-Dec-2009 03:18

dale77:
Thanks, they have 21, 47 and 91 element UHFs. My current ancient aerial (which was already installed when we moved in over 10 years ago) would be in the 91 element range. The dohickeys hanging off the back of the aerial have recently fallen off. Strangely this doesn't seem to have effected reception at all.

We are only 11km from the massive sugarloaf transmitter, admittedly in a traditionally dubious analogue reception area (behind large trees on the spit).

Hi Dale 77,

The "dohickeys" on the back of a UHF aerial are reflectors which (naturally) reflect the signal back onto the balun. They are most effective in areas 70-80 Kms away from the transmitter where you can see the transmitter but the signal is starting to loose it's strength so you want to gather every little bit of signal you can. In Canterbury we would be talking about out by Methven, etc.

The only thing that "wears out" on a UHF aerial is the balun (where the cable screws in) so I'd suggest that, unless the balun on your aerial is really rusted out, nothing is going to work better than your 91 element directional aerial 11 kms from Sugarloaf! - so if you've just replaced the cable and are running it directly to the TV, your problem is something else - trees! - and that's why the Sky installer would have installed the 91 element aerial in the first place because 11 kms from Sugarloaf a wet handkerchief should pick up a signal - so he would have only installed a big aerial if he had to!

If you have a thick belt of large, dense trees between your house and the transmitter then that will definately be your problem. I'd suggest concentrating on trying to move your aerial so the trees aren't in your "line of sight". The UHF signal has very similar properties to a light beam and you think what happens when you shine a torch at trees - the light splatters and dissipates - and that's what's probably happening to your UHF signal. Amplifying it will make a bit of a difference but usually if trees are your problem then shifting the aerial or trimming the trees are your only options.

Cheers, Wild Bill

dale77

291 posts

Ultimate Geek

Reply # 284135 20-Dec-2009 08:57

nothing is going to work better than your 91 element directional aerial 11 kms from Sugarloaf! - so if you've just replaced the cable and are running it directly to the TV, your problem is something else - trees! - and that's why the Sky installer would have installed the 91 element aerial in the first place because 11 kms from Sugarloaf a wet handkerchief should pick up a signal - so he would have only installed a big aerial if he had to!

Possibly the installer 10+ years ago couldn't be bothered thinking about which UHF size was required, so he just bought the biggest one. There have been some strange things about our aerial setup here, for a long time we have just been assuming it was well tuned at the point we arrived and attached our TV. The original setup was a power amped VHF aerial + the 91 element UHF. With an analogue TV Tuner in the HTPC we had terrible trouble getting any picture, and it turned out the signal was actually so strong is freaked out the tuner! The only way to get picture on the tuner was to attenuate the signal by 8db! Also, with the VHF powered job completely out of the loop, VHF reception is still fine on the lead from the UHF!

I'm encouraged that you reckon a wet hanky should get signal, cos as I said above I have this hunch that my problems might be too much signal, my poor tuner is getting blinded by the light! Perhaps I should just grab a $100 21-element job and try that?

If you have a thick belt of large, dense trees between your house and the transmitter then that will definately be your problem. I'd suggest concentrating on trying to move your aerial so the trees aren't in your "line of sight". The UHF signal has very similar properties to a light beam and you think what happens when you shine a torch at trees - the light splatters and dissipates - and that's what's probably happening to your UHF signal. Amplifying it will make a bit of a difference but usually if trees are your problem then shifting the aerial or trimming the trees are your only options.

Cheers, Wild Bill

Unfortunately we're right in behind them trees, which are away on public land on the south brighton domain.

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Reply # 284139 20-Dec-2009 09:21

You don't mention what analog UHF looks like. DVB-T transmitters are lower power than most analog channels. DVB-T from Sugarloaf is 47 dBW (50 kW) on channels 47, 49 and 50. Analog channel with similar power is CTV on channel 44 @ 44 dBW or 25 kW. The main UHF analog channels are way more powerful with Sky, Prime and Maori TV on 64 dBW. I would use CTV analog as a reference which is certainly snowy at that power in Belfast at 16 km.

Ross

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