No Channel 25 but everything else 99%

AndyBuzz

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Hi - can anyone provide some pointers ?

Since digital changeover I get a perfect and v strong signal except on Channel 25 - this carries ITV3, Quest etc. Auto search misses it, forced manual search puts it in memory - then the quality is circ 30% and no signal or total break-up. I live on South of the IOW (PO382LP), my nearest transmitter is Rowridge. I can see it - all brightly lit up at night.
I've been up ladders, moving the aerial, rotating it - whilst the wife shouts the quality number out of the window !
Is this likely interference from France ?
Though I've looked all sorts of places - I cannot find a digital advice line that I can ask.
Anyone know the phone number of an engineer at Rowridge ? !

Or seriously - where's the best place to go for advice ?

Many thanks
 
My first guess would be that you have too much signal getting to the TV. You are in one of those rare areas where the Wolfbane signal predictor actually recommends a set-top aerial. You may need to get yourself an attenuator to fit in the aerial lead.

Edit: Maplin in Newport have attenuators (6dB and 12 dB) in stock at the moment if that does seem necessary.


Very unlikely to be anything that an engineer at the transmitter can help with, nor interference from France.
 
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Try rotating the aerial to vertical polarisation if you haven't yet as that will equalise the COMs signal levels vs the PSBs (Hp psb=200 com=50; Vp all 200 - units are kW max erp). It will also vary the reflections off the foreground and or trees which may improve ch25?

Of course you have removed all amplification and fed the aerial direct into the TV? Amplifiers can add noise reducing quality and / or cause tuner overload issues that also appear as quality problems.

Overload? Errrmm .... possibly not at 8km - 5 miles distance from a non-omni transmit antenna... it will be restricted towards France and hence Chale/Ventnor also. I don't entirely trust Wolfbane predictions personally, and if the old analogues didn't cause overload issues why would the new digitals?... However, the cost of an attenuator isn't great (the fuel will be more) see TV Attenuators - Amplifiers & Distribution | Screwfix.com and may be the solution you need?
 
Overload? Errrmm .... possibly not at 8km - 5 miles distance from a non-omni transmit antenna... it will be restricted towards France and hence Chale/Ventnor also.
Looking at the location with Streetview, it really is a genuine "line of sight" (just up the road where the bushes are lower the mast is clearly visible), so even were it a low power transmitter (say 5kW) the signal would be pretty enormous at that distance. Not much potential for reflections though (apart from the Chillerton Down mast).
 
Thanks guys for replies - and looking at the maps !

I'll do some further experiments and get back. Yes - the experiment I did with the wife yelling the quality out of the window was with the aerial plugged straight into the back of the tv - and nothing else switched in near it. (there was only the humax so unplugged it)

I've got 2 other locations to try.

I'll look up the maplin part numbers of the aerials I've tried to let you know.

I'll also borrow a set-top aerial - I've got 2 stashed away somewhere.
 
(there was only the humax so unplugged it)

The Humax must use an hdmi lead to the TV. This may sound odd but try switching off the Humax and removing the hdmi lead from the TV. Interference from hdmi connections is very common and often affects just one mux frequency.

If that fails, why not try a cheap set top aerial? If that cures Ch 25 reception you probably do have too much signal from the external one. If an internal aerial gives weak or no signal on any channel you are not suffering from overload.
 

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