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280 posts

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Topic # 83484 17-May-2011 17:54
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Hi,

I want to split my UHF upto 4 ways.  I have got an old UHF aerial (guessing it is an old sky one) pointing to pinehill on the shore.  With a direct feed with old coaxial to a built in tuner I got a signal strength of 100 and quality between 50 and 60 depending on the channel.

I have run brand new sky approved cable from the aerial to a central point in the garage with my patch panel etc plugged into a 4 way splitter, with 2 feeds currently coming out, 1 to the tv with the built in tuner and 1 to the bedroom to a yet to be purchased HD STB. Everything is terminated with compression F connectors.  On the TV I can only get mediaworks and prime, no TVNZ, here are the respective strength and quality readings:

TNVZ S 26 Q 0
Mediaworks S 22 Q 57
Prime S26 Q 22

If I remove the splitter and use a straight connector I get all channels with the following

TVNZ S 50 Q 75
Mediaworks S 46, Q 100
Prime S 54 Q 100

There are also other other stats (Pre Viterbi, Post Viterbi, C/N, 5s, UEC, AGC) if they help.

I'm guessing that all my connections and cabling is fine, due the results if my remove the splitter.

So obviously the splitter is the problem.  Does the fact that the feed in the bedroom isn't connected to a receiver, or that there are 2 un-terminated connections on the splitter create the problem.  Or is there just not enough signal to split? Or is the aerial not quite alligned properly.
If there isn't enough signal to split, will a new aerial fix the problem or will it need amplifing somewhere?

Thanks

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  Reply # 470199 17-May-2011 18:20
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Yes and yes to the problems.

If you get a distribution amp, it terminates the antenna and then provides a robust 75 ohm output so it can better deal with non terminated outlets etc. with it direct to the antenna you will have reflections going all over the place up and down the cable reflecting off the unterminated jacks etc.

IMO they are really essential to getting things working well.




Richard rich.ms

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  Reply # 470295 17-May-2011 21:58
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richms: Yes and yes to the problems.

If you get a distribution amp, it terminates the antenna and then provides a robust 75 ohm output so it can better deal with non terminated outlets etc. with it direct to the antenna you will have reflections going all over the place up and down the cable reflecting off the unterminated jacks etc.

IMO they are really essential to getting things working well.

+1

And the amp also boosts the signal strength to compensate for the extra cable length and the splitter. Not sure how powerful the amp needs to be since your signal seems pretty weak already, so you might need a better aerial as well. I'm not an expert on aerials at all, maybe Richms has suggestion?




Qualified in business, certified in fibre, stuck in copper, have to keep going  ^_^

 
 
 
 


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  Reply # 470327 17-May-2011 22:51
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Considering you have an "old UHF antenna" it may be prudent to get a new one. The old one may be somewhat corroded and have poor joints? The old one I had here (also North Shore) was corroded and the PC board int the connector box kept filling up with water every time it rained. Not good for the signal. The new one is much better.
If a new antenna with the new coax doesn't work then progress to an amplifier or perhaps one antenna and coax run for each appliance?
Theoretically all outputs from the splitter should be terminated in 75 ohms with either an appliance or a 75ohm resistor.
Don't know your location but have you tried pointing at Waiatarua or SkyTower?
I presume you have the correct polarisation on the antenna? Waiatarua is Horizontal and I think Pinehill may be too. SkyTower is vertical.

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  Reply # 470330 17-May-2011 22:52
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Biggest you can is the usual idea for UHF when you have line of sight. More gain means less off axis crap getting in causing issues with amps and front ends. Its quite unusual to get too much signal, and if you do (like you live out west auckland) you can just whack an attenuator on it to get rid of it.

If its not line of sight then a less directional one like the phased arrays can work better as it will not have the same variance in signal levels as the tree or whatever in the way blows around.




Richard rich.ms



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  Reply # 476364 31-May-2011 20:00
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I'm in Torbay, so pinehill is definetly closer (only 4km's in a straight line), although there is only about 15 degrees difference to where I would have to point the aerial to be at the sky tower.  I don't seem to have a direct line of sight, i.e. I can't see the transmitter when I stand on the roof with binoculars.  


I'll try a new aerial at some point,  does more elements translate to size?


  

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