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Fat bottom Trump
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  # 2044071 26-Jun-2018 13:04
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To be honest, I completely forgot about that other thread. My apologies. I fear this is another symptom of advancing age. I had given up on the UHF for the time being, then bought a new receiver that includes UHF which put it back in my mind again and I decided to look for a solution. I forgot that I had already done this. My brain plays tricks on me from time to time. 

 

To get to your point, I have carefully checked the antenna for movement in relation to reception quality and have never been able to find the slightest connection. There is no observable movement at all except in very strong winds, and even then only very little. Reception quality sometimes is perfect even when strong winds are blowing and sometimes crap when it is completely windless. I can't find any connection there. Also, reception was excellent for many years when I also had no guy wires or other support. Naturally I can't rule anything out completely, but antenna movement just doesn't seem to be the issue.

 

 

 

 





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  # 2044097 26-Jun-2018 13:37
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Judging from all the comments so far and looking at your setup and location I'd suspect just plain variation in signal propogation from the Tx causing fluctuations in signal strength. UHF can be very fickle in this respect. It's usually caused by variations in wx patterns, atmospheric ducting, temperature inversion and many other things beyond our control. Rather like getting rain fade on satellite reception.

 

Definitely worth trying a masthead amp right up at the antenna and maybe try a phased array instead.

 

 


 
 
 
 




Fat bottom Trump
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  # 2044113 26-Jun-2018 14:05
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I'm inclined to agree with you. I don't have the technical expertise to properly analyse this but atmospheric ducting seemed to make sense when I read about it. Especially as there is no apparent link to weather or other variables. Sometimes it just works well, sometimes it doesn't, and that is about all. Of course there would not be a problem if I could boost the signal a little.

 

I have thought about improving the antenna but don't know if it would make enough difference to be worth it. I would like to try the masthead amp and probably will at some point, but it involves not only bringing the antenna down, but putting it back again just to test and I'm nervous about the reliability of the amp. If it dies for any reason, everything stops and the antenna has to be brought down again to replace or remove it. There is no fall-back to passive operation.

 

I started this thread (and the other one I forgot about) to garner information, in the hope of finding a fix, but in any case to improve my insight and understanding of the issue. In that I have certainly succeeded. I feel I understand the problem much better and I really appreciate all the helpful comments. At this time I will confine myself to small experiments with antenna direction but when the weather improves I will consider a better antenna and masthead amp. I prefer to make any changes that involve bringing the antenna down all at once.

 

Thanks again for all the suggestions.

 

 





I reject your reality and substitute my own. - Adam Savage
 


Banana?
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  # 2044121 26-Jun-2018 14:19
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All I've ever seen go wrong with Masthead amps is the power supply for the injector - which is in the house.




Fat bottom Trump
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  # 2044123 26-Jun-2018 14:20
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Good to know. Thanks.

 

 





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  # 2044507 27-Jun-2018 04:27
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Is the antenna really looking straight into those 2 trees?

 

 




Fat bottom Trump
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  # 2044638 27-Jun-2018 10:46
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No, the trees do not actually obscure it. Possibly a few branches as I can not look from the antenna's height position, but no major obstruction. I realise the trees could have an effect. What I don't get is the variation. Sometimes the signal seems perfect, at least in terms of picture quality (it is never as strong on the TVNZmux), other times it constantly pixelates. There seems to be no relation between this and wind or other weather conditions. I cannot establish any pattern at all.

 

 





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  # 2044665 27-Jun-2018 11:20
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Rikkitic:

 

 What I don't get is the variation. Sometimes the signal seems perfect, at least in terms of picture quality (it is never as strong on the TVNZmux), other times it constantly pixelates. There seems to be no relation between this and wind or other weather conditions. I cannot establish any pattern at all.

 

EMF propagation , particularly fringe coverage is a fairly dark art,  To get a handle on what is really happening you will probably need a field strength meter/spectrum analyser and a bunch of time to record levels based on conditions..

 

Atmospherics can play a part, and also if the LOS is really low to the ground trees Kms away could have an impact, heck in the days of Analouge UHF the neighbour putting a new roof on his shed behind your house was often a lovely source of ghosting.... 

 

 


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  # 2044719 27-Jun-2018 13:30
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You should realize that the beamwidth of that antenna doesnt just pick up in a direct straight line. Im pretty sure it will be those large trees to blame, wet trees , dry tree , branches moving in the wind, etc

 

20 km distance isnt even fringe reception..

 

Do you have a google pin for your house location? it would be fun to play on google earth to see the path to the MT Erin tower.

 

 

 

 

 

 

 

 




Fat bottom Trump
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  # 2044785 27-Jun-2018 14:14
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Don't really want to publish my precise location but would be happy to PM it. I'm pretty sure the reception maps say we can't get any signal.

 

 

 

 





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Fat bottom Trump
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  # 2044852 27-Jun-2018 16:03
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I have been playing on Google Maps today and the Mt Erin transmitter is about 17 kms from us LOS. There is a range of low hills nearby blocking our LOS to Mt Erin, otherwise we would have perfect reception.

 

 





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  # 2044862 27-Jun-2018 16:26
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Rikkitic:

 

There is a range of low hills nearby blocking our LOS to Mt Erin, otherwise we would have perfect reception.

 

 

What's on the hills, bush or is it just grassland?




Fat bottom Trump
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  # 2044865 27-Jun-2018 16:31
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Rocky grassland, cropped bare. No bush to speak of.

 

 





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  # 2045124 28-Jun-2018 06:10
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Can you check the BER (Bit error rate) in the tuning menus somewhere?

 

 


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  # 2045134 28-Jun-2018 07:36
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When you say LOS blocked by low hills, how high are they? Mt Erin is apparently 490m.

In my location I'm about 60km from the transmitter. When I replaced the aerial I went with the same high gain type but going on signal level reported by set I possibly could have used a smaller aerial. If the long aerial twists I lose the highest frequency mux while the others hang on.

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