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Permalink Reply by Peter Johnson on February 23, 2015 at 12:24

I to are having problems with TVNZ ch. 1, 2, 1+1, and 2+1.  This started about xmas  2014 but I put it down to old stranded cables used when the house was built 1989.  I have since replaced the main outlet with RG59 but no difference.

On my Sony TV it shows, when you go to tech. section, the signal strength of each channel.  TV 1 (2) a bar and it is saying good, 2/3 length, but if I go to TV 3 the bar is green and is green along the full length.

On Sunday 22-2-1015 about 8:30 pm TV 1 pixelated about three times but was only across the middle, most upsetting as I thought the TV was breaking down.

I have always had good reception as I am 7 km in direct line and I can clearly see the transmitting aerials on Kopukairua.

Now what?  Peter J.

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Permalink Reply by Biggles on February 23, 2015 at 13:44

What sort of antenna are you using?

You should be using rg6 cable, not rg59.

Occasional pixellation is not uncommon even with strong signals. We are line of sight to Waiatarua (17km) and have a 47 el antenna with full green bars on the Sony. We still get the odd bit of pixellation now and then (usually around 6pm) which I think is due to atmospherics and/or signal reflections from aircraft. It's fairly rare though.

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Permalink Reply by Peter Johnson on February 23, 2015 at 16:06

Thanks for reply.  I was told by an aerial tech to use 59 as RG 6 is "messy" to terminate easily.  The UHF aerial was previously on Te Aroha, over 40km but  T A could be seen on a good clear day, changed direction and to vert. about 6-8 months ago.  Has 7 "X" elements on it.

Peter J.

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Permalink Reply by nzdtv.com on February 23, 2015 at 16:25

Then you need a new tech giving out bad info like that!

rg59 cable has a huge signal loss at UHF frequiencys

replace it

 

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Permalink Reply by Peter Johnson on February 23, 2015 at 16:54

Ok thanks,  estimate it is about 26-28m from wall to UHF aerial plus make up some wall to TV leads with the RG 6.  Would a new aerial with more elements help?  The line of sight is only 7km and only TVNZ.

Do you have an address so I can talk to them about the low signal from Kopukairua?

Peter J. 

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Permalink Reply by Biggles on February 23, 2015 at 17:00

Your Aerial Tech is obviously unprofessional. RG6 is easy to terminate and RG59 is rubbish cable at UHF. I used screw on f29 connectors on my rg6 but crimp connectors are far superior. I'd recommend you replace the whole co-ax run and terminate correctly with f connectors. Also check the antenna has clean corrosion free connectors.

Be aware also that many short cables that connect from the wall socket to the TV are rubbish at UHF. Over the years I've had a few brand new ones that wouldn't even work with VHF analogue.

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Permalink Reply by nzdtv.com on February 23, 2015 at 17:22

Wait, I reread above and you say you are also using a masthead amp? you should not need a masthead amp being only 7K away. Your issue may actually be that you have too much signal.

A real shonkey setup by the sound of things.

Replace you cables with rg6 first if that doesnt fix it remove the mast head amp.

Maybe consider getting someone to come in and fix it

 

 

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Permalink Reply by Peter Johnson on February 23, 2015 at 19:00

I donot have a masthead amp.  Will change cables to RG 6 but why is it only TVNZ which is bad??

Peter J.

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Permalink Reply by nzdtv.com on February 23, 2015 at 19:12

Sorry my mistake about the masthead amp. Each mux (group of channels) broadcast on their own frequency. Most antennas do not have a flat signal gain across the channel that they cover, gain might be good on low end channels but on the higher ones it might drop off  meaning you have poor signal on one group of channels such as the TVNZ when it reaches your tv set.. 26 meters of RG59 is easily enough to lose most of the signal received by your antenna.

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Permalink Reply by Biggles on February 23, 2015 at 19:17

Only TVNZ is bad because you have a problem which is affecting only the TVNZ mux. There are many possible causes for one mux to be affected more than others. Without inspecting your installation and checking signal strength and quality with sophisticated equipment it's impossible to diagnose the problem. Generally it is a result of poor antenna installation and cabling or some sort of interference affecting just the one mux channel. Do you have Sky with an rf modulator? That could easily wipe out just one mux. Have you still got the old VHF antenna connected with the UHF antenna? If you are only 7km from the Tx and can see it you can probably get a signal with an indoor antenna. When I setup Freeview here in North Shore I was able to get a picture on all channels off Waiatarua with just a bit of wire stuck in the antenna socket.

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Permalink Reply by Peter Johnson on February 23, 2015 at 19:40

Thanks again.  The old anlog aerials were removed soon after some changes were made to Kopukairua, about 9 months ago.  Donot have Sky and never will.  I checked the security of the aerial mast to the roof recently but when it clears a bit I will recheck the aerial connection on the aerial. 

Peter J.

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Permalink Reply by Peter Johnson on February 24, 2015 at 16:59

Hello gentlemen, Biggles and nzdtv, through your kind help my low signal problems appear to be fixed.  I replaced the aerial cable with RG6 and also replaced a lead (it had no brand on it) with an RG6 and confirmed any other leads were also RG6.

All channels on the Sony TV show -450 on something called AGC so picture much improved.

Thanks again,  Peter J.

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