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Retune 21-3-18 (Rowridge) - lost Com 8 (Resolved)

peterworks

peterworks

Ye Olde Bowler
After the retune today I cannot get Com 8 - it was fine (though a little weak) before.
My TV manages to get it at a signal strength of 10-14 pct and quality about 50 to 60 pct.
Com 7 appears fine.
This is what I should be getting:
Capture21-03-2018-17.15.09.jpg
Anyone else on this transmitter seeing this problem ? I am on the Isle of Wight approx 15 miles from the Rowridge.
 
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I notice someone else is possibly having a problem with Sutton Coldfield and COM7/8 2 Muxes/Channels vanished at retune - Still not back. I'm wondering whether the idea of COM7/8 being a single frequency network (every transmitter having COM7 on same frequency etc) hasn't been thought through and tested properly. Is there another transmitter nearby also with COM8 on UHF 56? Could it be that the transmitters are interfering with each other (oo-er!) instead of working together as a SFN?
 
From the Freeview site:
Freeview said:
I’ve retuned but I’m still missing some channels. What do I do?

Retuning your Freeview TV or box should restore your channels in most cases. However, in some cases you may need a new aerial to continue watching all available services. For more information or help with this call the Freeview Advice Line on freephone 0808 100 0288. Support may be available where a new aerial is required.
Click to expand...
 
peterworks said:
After the retune today I cannot get Com 8 - it was fine (though a little weak) before.
Click to expand...
What group aerial have you got? Sounds like you need a wideband and you have a group A.
My TV manages to get it at a signal strength of 10-14 pct and quality about 50 to 60 pct.
Click to expand...
Very marginal then.
You could try a masthead amp., which will probably lift you above threshold, but it seems a bit iffy on your existing aerial.
Com 7 appears fine.
Click to expand...
Well it would because, at the moment, it is still in band for your aerial.
I am on the Isle of Wight approx 15 miles from the Rowridge
Click to expand...
Is the IoW that big then? I've never been (apart from before my memory!) and vaguely thought Rowridge was central-ish.
Must look at the map again.
 
EEPhil said:
Is there another transmitter nearby also with COM8 on UHF 56?
Click to expand...
CP and Mendip (oops, not yet). But they're miles away.
Could it be that the transmitters are interfering with each other (oo-er!) instead of working together as a SFN?
Click to expand...
If outside the Guard Interval, then yes, but they'll be so weak at that distance it's not going to be significant. My money's on the aerial.
 
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prpr said:
What group aerial have you got? Sounds like you need a wideband and you have a group A.
Click to expand...
It was only installed two years ago but I will check tomorrow.
All other frequencies are 60-70 strength and 100 pct quality so would be reluctant to use a masthead amp.
The IoW is about 23 miles wide and Rowridge is slightly West of centre. I live on the East coast.
 
peterworks said:
After the retune today I cannot get Com 8 - it was fine (though a little weak) before.
Click to expand...

I am about 30 miles roughly ENE from Rowridge. Post-retune signal strength of channels on COM8 is pretty much unchanged (around 50 percent with 100 percent quality). I'm fairly sure the aerial is wide-band, installed 10yrs ago. Sorry this doesn't help fix your problem but it does add weight to the theory that your aerial may be unsuitable for CH56.
 
Thanks prpr for your analysis and thanks alanofcleeves for your confirmation that all should be okay.
Have checked and have a red stopper on aerial so it is a group A. I seem to recall that was the recommendation for Rowridge at the time (December 2014).
peterworks said:
installed two years ago
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Oh how the memory plays tricks ! Was actually over three years ago.

Will source a wideband...
 
I would probably go for a log periodic as they have less windage - 28 element is a standard size for a log. Vision and Blake are usually good, but there are others. Looks like you can get group T aerials now, so I'd probably go with one of those.
Stay away from the cheap crap and the big blingy stuff (IMHO).
Depends on your definition of "reasonably".
 
peterworks said:
Can anyone recommend a reasonably priced wideband aerial please ?
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If you are paying somebody to fit it, the cost of the hardware is a minor proportion of the overall cost. If you are doing it yourself, the last thing you want is to have to do it again any time soon. Buy cheap, pay twice. Pay more than strictly necessary and what is the loss? Only a few quid.

Go for quality every time (and that doesn't mean what you can source from B&Q).
 
A Log periodic is by far your best bet.
Something like THIS or THIS in the loft. I have a similar one to the latter (Labgear Compact Log) on my eves and it works a treat.

Is not group T what they used to call Wideband (W)?
 
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Thanks Trev - my current aerial is in the loft and gives excellent reception (except for Com 8 :(). Will go for the loft version you have linked to.
 
Trev said:
Is not group T what they used to call Wideband (W)?
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Group W is for frequencies 21 to 68, while group T is for frequencies 21 and 60.
The theoretically it should be possible to manufacturer the group T with a slightly higher gain as it does not also have to be concerned with reception of Ch61 to Ch68.

If someone is after a group T I'm not sure that there is anything stopping a manufacture from just labeling the existing W aerial as T unless the gain they quote does not apply to any of the cH21-ch61 frequencies, in which case they would also have to change their tech spec to reflect a lower gain.
 
I got a big (18 element) Blake DMX ? from ATV for our Rowridge reception. That was about 2 years ago. I can't recall whether it's grouped or wideband but I suspect w/b. We're about the same distance as you from the tx (Dibden Purlieu) but we use an amplifier as well - a bit of land and a lot of trees in the way :) .
 
Just been checking reception - I had given up even tuning Com8 as it had nothing we wanted, but I checked reception for channel 56 and got absolutely zilch, like it was non-existent. That doesn't seem to bode well for Com7 moving from 31 to 55 in May, even allowing for power disparities. I wonder if it'll need another new aerial?

I notice L-SOT has moved from 29 to 37 (which used to be Com8) - not sure why they moved Com8 then :confused:
 
Trev said:
Is not group T what they used to call Wideband (W)?
Click to expand...
T has (or should have) a filter of some sort to try and get rid of the 800 MHz stuff, but I suppose that is less relevant now that 700 MHz is being cleared. Still, it's better to filter out the crap you don't need, especially if you're going to amplify anywhere in the chain.
 
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