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62 posts

Master Geek


Topic # 87231 23-Jul-2011 03:00

Hey guys,

I'm looking for some pointers on how to improve my DVB-T reception.

Equipment:
TV - Sony Bravia KDL-EX500 (built-in FreeviewHD receiver)
Aerials - VHF and UHF (see pics) on the same 1.8m mast connected through Kingray MHU24G amplifier/diplexer by a direct cable to only the above TV. Amp is mounted on the mast about 1m below the lower aerial.
Aerials are probably quite old, I replaced cable going Aerials-to-Amplifier, but Amp-to-TV is still the old one.

Location:
I live in Mairangi Bay - have a look on the map. The lines on the pic point to Waiatarua and Pinehill. My aerials point to Waiatarua (25.5km from me), even though Pinehill is only 2km away. Because that's how it was when I moved in and that's where most neighbours' aerials are pointed.

Problems:
Unable to receive TVNZ signal, but can receive Mediaworks and Kordia quite well.

Notes:
My VHF and UHF aerials are on the same mast. The tricky part is when I first started without touching anything I received TVNZ and Mediaworks, but Kordia was sketchy. Then I put the UHF aerial above VHF (about 60cm between them) and replaced the aerial-to-amp cables. After realigning the aerial I could receive Mediaworks and Kordia well, but not TVNZ. The photos of the TV System Info screen are after the aerials got swapped.

Potential solutions?:
I am thinking of the following solutions:
1) Replace amp-to-TV cable,
2) Put a stronger amplifier in-line
3) Point aerial to Pinehill
4) Call an aerial installer :)

So yeah if anyone is able to offer some insightful advice - that would be awesome!
Cheers





 


On TV1 (TVNZ)


TV3 (mediaworks)


Prime (Kordia)



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148 posts

Master Geek


  Reply # 497006 23-Jul-2011 08:12
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Nice work :-)

Point to Pinehill.

I think because you only use dvb-t, you don't need to worry about extra amplification, but you may consider even just running the uhf signal and taking the vhf out completely.

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  Reply # 497009 23-Jul-2011 08:17
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I first thing I would try is to point the aerial to Pine hill and then retune the channel on your TV (Waiatarua uses different frequency).

The second thing is to consider replacing the cables.

The third thing is to get rid of the VHF aerial together, if you are not planning to watch analogue TV from now.

Last thing to try is to call an installer.

FYI, I am not an expert on this things.  This is just my humble opinion.

Cheers!

 
 
 
 


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  Reply # 497013 23-Jul-2011 08:43
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fatboy: Hey guys,

My VHF and UHF aerials are on the same mast. The tricky part is when I first started without touching anything I received TVNZ and Mediaworks, but Kordia was sketchy. Then I put the UHF aerial above VHF (about 60cm between them) and replaced the aerial-to-amp cables. After realigning the aerial I could receive Mediaworks and Kordia well, but not TVNZ. The photos of the TV System Info screen are after the aerials got swapped.



Try removing the vhf antenna and the amp leaving the UHF by itself at the top of the pole.
I had similar problems with a setup im a valley in Glenfield. No amp but the VHF and UHF antenna  (although separate co-ax leads to the lounge) were interacting with each other (too close to each other) and could barely get any signal at all.
I moved the UHF about 15ft away to top of a separate J-Pole mounted slightly lower down and got 100 + 100 strength and quality. I thought I was going to need an amp but worked OK without and way out of line of sight with the TX at Waiatarua. Also be very careful with alignment. Sometimes a few degrees either way can make a big difference.



62 posts

Master Geek


  Reply # 497026 23-Jul-2011 09:38

Great, thanks guys keep the responses coming :)

Looks like the weather is going to play nice today, so I think I will indeed try pointing at Pinehill.

However can someone tell me how much a tree would influence a signal? There's a large tall tree right in the way. Also, I don't quite have line of sight to Pinehill, but houses are not too tall that way. Ok, so I shall give that a go first maybe even without VHF antenna. Will let you know how I go.

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  Reply # 497031 23-Jul-2011 09:48
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Don't worry about the trees too much at this stage.  Point the UHF aerial to pinehill and remove the VHF one and see how it goes.
Smile

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  Reply # 497037 23-Jul-2011 10:25
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Try adjusting the gain whilst someone is looking at the diagnostics , if no good ,then remove the VHF & repeat whilst moving the UHF up / down the mast



62 posts

Master Geek


  Reply # 497162 23-Jul-2011 18:06

Unfortunately didn't get a chance to do anything to the aerials today, hopefully tomorrow.

But before that can someone confirm whether the UHF antenna needs to be horizontal when installed on the mast and how important is it for the signal strength/quality?

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  Reply # 497193 23-Jul-2011 19:32
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Both pinehill and waitarua are horizontal, that is critical. The tree will not be helping and it will depend on how wet it is as to how it affects it.

Those kingrays with their unshielded PCBs and crap terminals are pretty bad. IMO take the antenna straight to the UHF, forget the amp and as a result its indoor injector and go straight to the reciver with a single cable run of decent stuff and see how it goes.

I have just had to troubleshoot why I was getting massive problems on the mediaworks mux in the garage and it was replacing an old saddleclamp splitter under the house with a straight thru connection that solved it. Those things are horrible.




Richard rich.ms



62 posts

Master Geek


  Reply # 500361 1-Aug-2011 14:48

Sorry for a bit of a delay in updating the problem, however I'm happy to report that it is now resolved! WooT!!!! Cool

What I did:

To improve reception:
- removed VHF aerial off altogether, since it would be obsolete in a year anyway
- removed Amp/diplexer
- replaced cable going Aerial --> TV

Necessary changes/laziness:
- put a splitter behind the TV, to connect PlayTV
- ran out of cable so had to put in 1 connection in the cable going Aerial --> TV (splitter)
- did not change orientation of the UHF aerial, so still pointing to Waiatarua (I live in Mairangi Bay)
Notes: all connections were crimped F-connectors, apart from the ones on the aerial itself, which was a clamp-type one.

Outcome:
Judging by the System info screen in the TV the reception is around 75-80% strength-wise and 100%quality. All channels worked fine for the last week with no pixelating on TV or PlayTV so far Smile

Overall:
Even though I'm not too sure which of the changes did the trick, however I'm highly suspect of the Amp/diplexer (due to the above mentioned flaws in connector/PCB design) or interference from the VHF aerial. But I'm stocked to have this fixed, and THANKS TO EVERYONE for your helpful suggestions! Laughing!

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  Reply # 500564 1-Aug-2011 21:08
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- put a splitter behind the TV, to connect PlayTV


Do you need to inject power to the splitter?  FYI, I don't know much about these things, so I might be talking rubbish.

By the way, do you have an idea how old is the UHF antenna.

Anyway, it is good to know the problem is sorted!



62 posts

Master Geek


  Reply # 500629 2-Aug-2011 01:50

No, I used a passive splitter. I don't think I need a powered/amplifying(?) one, since it seems to work fine now, and it would be quite a hassle having another plug/wire behind the tv.

As to the age of the UHF aerial: at a guess 8-10 years, but definitely more than 5, since that's how long we lived in this house and we didn't put the aerial up there. Why are you asking?

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