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TV tuning issue


RickS

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This is driving me crazy!

I have a bog standard log periodic aerial on a pole and it works fine - mostly. I have to turn it or jiggle the wire occasionally for a couple of channels but usually pretty good.

I tried a new (cheap but small) aerial today and got nothing after auto tuning, but now I have lost quite a few channels - the ones you actually watch rather than the jewellery channel (!). etc

The problem I think is that originally I tuned the TV at home and got all the channels i wanted so using it on the boat meant the tuning was there but not always perfect - hence the wire jiggling etc.

Is it just a case of moving the aerial and auto-tuning until I get the channels I want or is there a better way.

Would one of those compact omni-directional aerials work better?

Thanks 

 

Just to add - I am getting everything except channels 1 - 10

Edited by RickS
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Where is the boat, could you be in the area for an infill transmitter? They often have fewer channels and some/many are vertically polarized rather than the horizontal for the main transmitters.

 

The twisting of the cable makes me suspect that you may have water in the cable or some other form of damage. Unless the boat is on the same transmitter as your home you will have to do a re-tune. Different transmitters use different frequencies, even on DTV.

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Maybe obviously, but the log periodic aerial must point directly at the transmitter if in a poor signal area.  If the cable needs waggling about, it sounds like either the connectors are dirty/corroded or the cable has an internal cracked core, in which case you need a new cable.

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Sandy Heath transmitter is horizontally polarised, You need the antenna oriented like this, not like this.

 

1 hour ago, RickS said:

Would one of those compact omni-directional aerials work better?

Almost certainly not. A log periodic pointed correctly at the transmitter will outperform an omni directional. This assumes everything else is good. Cable, connections etc.

Getting the aerial higher may help you. Trees and buildings in the way absorb signal.

The cable and connections have to be good first. Any other changes will be useless if these are poor.

 

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28 minutes ago, Jen-in-Wellies said:

 

The cable and connections have to be good first. Any other changes will be useless if these are poor.

 

Had this last week with my Moonraker, hardly any channels being picked up. I had to remake the coax connection to it, 

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When ever you move the boat (and therefore the telly) you need to point the aerial to the best transmitter and in the correct polarization (normally horizontal for main transmitters but sometimes vertical for relays) then retune the telly. Even moving half a mile can mean you need a retune.

To find the location of the transmitter I use an app on my phone called UK Aerial Alignment.

 

As all above have said clean connections are a must.

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If you have a smart phone try using the 'UK Aerial Alignment' app from Google Play. I used it all over the Midlands and North West last year and could usually get at least one or two of the major channels. I find it works better if you stand away from the boat.

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44 minutes ago, Midnight said:

If you have a smart phone try using the 'UK Aerial Alignment' app from Google Play. I used it all over the Midlands and North West last year and could usually get at least one or two of the major channels. I find it works better if you stand away from the boat.

I use the same App and find that I have to stand well away from any steel boats. 

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1 hour ago, Midnight said:

If you have a smart phone try using the 'UK Aerial Alignment' app from Google Play. I used it all over the Midlands and North West last year and could usually get at least one or two of the major channels. I find it works better if you stand away from the boat.

Anything that depends on a magnetic compass for direction will work better well away from a metal boat!

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Thanks all, and apologies for not responding sooner.

Eventually, after much turning the aerial and re-tuning again and again,... and again, I finally managed to get it back to how it was. What a faff!

I appreciate what several are saying about less than perfect cable and connectors, but I should have explained  myself better. Now that the channels are tuned, if one gets a bit of interference, I can improve it by pushing or pulling more or less cable through the gland (I know that sounds wrong). It seems to interact with the metal pole that the aerial is attached to, rather than wiggling the wire, which was a poor choice of word.

I was hoping that someone might say that the more compact omnidirectional aerial were much better as, at the moment, the aerial pole goes through a hole in the lip of the cabin roof that extends over the well deck. I have just had a new cratch cover fitted which, of course, covers that hole, so I have loosen one corner of the cover, which defeats the point somewhat and looks a bit naff. So i was hoping another aerial type might be better so i could just pass the cable through the hole and up under the cover - hope that makes sense.

What would be the best way of still using the log periodic whilst still having the cover on properly?

Thanks again for your help 

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You seem to be resistant to the idea that it could be a problem with the cable, but what you are describing sounds very like a problem with the cable...

A coaxial cable shields the signal travelling down the central conductor. It should be pretty immune to proximity to other things, like poles. A break in the central conductor could make, or break with varying degrees of signal transmission depending on small amounts of movement.

Try a new cable and connectors between aerial and TV, just run it through a window for now. See if it improves matters. A cheap thing to check and replace if it turns out to be the thing.

Edited by Jen-in-Wellies
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1 hour ago, Jen-in-Wellies said:

You seem to be resistant to the idea that it could be a problem with the cable, but what you are describing sounds very like a problem with the cable...

A coaxial cable shields the signal travelling down the central conductor. It should be pretty immune to proximity to other things, like poles. A break in the central conductor could make, or break with varying degrees of signal transmission depending on small amounts of movement.

Try a new cable and connectors between aerial and TV, just run it through a window for now. See if it improves matters. A cheap thing to check and replace if it turns out to be the thing.

 

Could not say it better.

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1 hour ago, Jen-in-Wellies said:

You seem to be resistant to the idea that it could be a problem with the cable, but what you are describing sounds very like a problem with the cable...

A coaxial cable shields the signal travelling down the central conductor. It should be pretty immune to proximity to other things, like poles. A break in the central conductor could make, or break with varying degrees of signal transmission depending on small amounts of movement.

Try a new cable and connectors between aerial and TV, just run it through a window for now. See if it improves matters. A cheap thing to check and replace if it turns out to be the thing.

Thanks Jen. Not resistant, just didn't think it might be the cable as I had mis-represented myself by the term wiggling. Having read your post, I shall revise my thinking.

 

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15 hours ago, Jen-in-Wellies said:

You seem to be resistant to the idea that it could be a problem with the cable, but what you are describing sounds very like a problem with the cable...

A coaxial cable shields the signal travelling down the central conductor. It should be pretty immune to proximity to other things, like poles. A break in the central conductor could make, or break with varying degrees of signal transmission depending on small amounts of movement.

Try a new cable and connectors between aerial and TV, just run it through a window for now. See if it improves matters. A cheap thing to check and replace if it turns out to be the thing.

 

 

A couple of years ago with my basic Log aerial I meticulously re-worked the connections to make sure they were perfect and at the same, perhaps this was overkill, but I upgraded the cable to Quadshield coaxial as well. The difference was truly remarkable.  When out and about cruising all over the country it went from getting a signal only 20% of the time to about 90% afterwards, and often when I moor up I don't even have to direct or raise the aerial. 

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54 minutes ago, Grassman said:

 

 

A couple of years ago with my basic Log aerial I meticulously re-worked the connections to make sure they were perfect and at the same, perhaps this was overkill, but I upgraded the cable to Quadshield coaxial as well. The difference was truly remarkable.  When out and about cruising all over the country it went from getting a signal only 20% of the time to about 90% afterwards, and often when I moor up I don't even have to direct or raise the aerial. 

Quadshield coax doesn't have any lower loss than good-quality conventional coax (note -- good quality) and is more expensive, thicker and harder to bend and route and get into connectors.

 

It's only useful in cases where there are very high levels of interference (e.g. a noisy inverter close to the cable).

 

If this wasn't the case with Grassman, he'd have got the same result with new good-quality coax (especially low-loss if the cable is long) and connectors. Don't forget that low-loss coax is also bigger diameter than the thin (especially cheap) stuff, because physics... 😉

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On 19/01/2022 at 10:48, IanD said:

Quadshield coax doesn't have any lower loss than good-quality conventional coax (note -- good quality) and is more expensive, thicker and harder to bend and route and get into connectors.

 

It's only useful in cases where there are very high levels of interference (e.g. a noisy inverter close to the cable).

 

If this wasn't the case with Grassman, he'd have got the same result with new good-quality coax (especially low-loss if the cable is long) and connectors. Don't forget that low-loss coax is also bigger diameter than the thin (especially cheap) stuff, because physics... 😉

I think that was my problem. The aerial cable runs under the gunwale alongside the electric and HDMI cables and the quadshield sorted it.

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2 hours ago, Grassman said:

I think that was my problem. The aerial cable runs under the gunwale alongside the electric and HDMI cables and the quadshield sorted it.

If an STB or TV (whatever is being used to receive the signal) has meters which show signal level and signal quality separately (a lot of DTV receivers do, but not all), a weak signal and a stronger signal with interference show up differently and this can help diagnose what is wrong -- quadshield will fix interference (low quality strong signal) but not a weak signal (needs better aerial and/or lower-loss cable).

 

Glad the quadshield worked for you though 😉

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2 minutes ago, MtB said:

Surely the best way around all this is to watch telly on a computer?

Could be -- presumably with an external aerial, as everyone recommends to get a better signal?

 

So guess how the external aerial connects to the Wi-Fi router... 😉

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