JohnH77 – 53 minutes ago  » 

Are both the signal strength and quality very stable? Or do they vary and increase and decrease as you look at them? If so, you have reflections or co-channel interference.

What is your postcode? Check which channels you should be tuning to at http://www.digitaluk.co.uk/coveragechecker/ – be sure to select Detailed View.

As suggested above do a manual retune of the correct transmitter after deleting all saved TV stations. Delete any stations with 800 numbers – they are duplicates.

The whole point of doing a manual tune is to exclude getting channels in the 800’s. They aren’t duplicates. They may or may not be the correct channels from the best transmitter. It entirely depends on the UHF channels used by the two (or more transmitters in range).

Only if the highest UHF channel used by the desired transmitter is lower than the lowest used by any of the others would it be safe to just delete channels in the 800s.

Scanning starts at UHF 21 and goes up to 68.

When a valid Mux is found the channels within it are stored at the correct lower lcns. When a duplicate is found which may or may not be the correct one the channels within the duplicate mux are stored in the 800’s.

This will always happen in the UHF channel range in all transmitters in range overlap in some way. If you know what transmitters are involved it’s very easy to predict what will happen.

Use Excel to create 3 columns

Col 1 Transmitter Name

Col 2 UHF MUX

Col 3 Mux Name

When all of them are entered select the whole table and sort in ascending order on Col 1

You can instantly see which MUX will be incorrectly tuned.

Artificial example based on Sutton Coldfield, Ridge Hill and Lark Stoke all of which can be used in some areas of my home town (Redditch).

Here is the unsorted data Sut ton Coldfield, Ridge Hill and then Lark Stoke

Transmitter UHF MUX

Sutton Coldfield 43 PSB1

Sutton Coldfield 46 PSB2

Sutton Coldfield 40 PSB3

Sutton Coldfield 42 COM 4

Sutton Coldfield 45 COM5

Sutton Coldfield 39 COM 6

Sutton Coldfield 55 COM 7

Sutton Coldfield 56 COM 8

Ridge Hill 28 PSB1

Ridge Hill 25 PSB2

Ridge Hill 22 PSB3

Ridge Hill 33 COM 4

Ridge Hill 24 COM5

Ridge Hill 27 COM 6

Ridge Hill 55 COM 7

Ridge Hill 56 COM 8

Lark Stoke 26 PSB1

Lark Stoke 23 PSB2

Lark Stoke 30 PSB3

Lark Stoke 33 COM 4

Lark Stoke 35 COM5

Lark Stoke 48 COM 6

Note Sutton Coldfield and Ridge Hill use the same UHF channels for COM 7 and the same for COM 8 (55 and 56),

This is because thew two transmitters use a SFN (single frequency network for com 7 and com . Differentiating between them basically depends on the distance to either transmitter at your location.

Here’s the table sorted by UHF channels

Transmitter UHF MUX

Ridge Hill 22 PSB3

Lark Stoke 23 PSB2

Ridge Hill 24 COM5

Ridge Hill 25 PSB2

Lark Stoke 26 PSB1

Ridge Hill 27 COM 6

Ridge Hill 28 PSB1

Lark Stoke 30 PSB3

Ridge Hill 33 COM 4

Lark Stoke 33 COM 4

Lark Stoke 35 COM5

Sutton Coldfield 39 COM 6

Sutton Coldfield 40 PSB3

Sutton Coldfield 42 COM 4

Sutton Coldfield 43 PSB1

Sutton Coldfield 45 COM5

Sutton Coldfield 46 PSB2

Lark Stoke 48 COM 6

Sutton Coldfield 55 COM 7

Ridge Hill 55 COM 7

Sutton Coldfield 56 COM 8

Ridge Hill 56 COM 8

You can see that none of the Mux will be first found on the same transmitter so deleting all the 800’s will achieve nothing.

Subset

Transmitter UHF MUX

Ridge Hill 22 PSB3

Lark Stoke 23 PSB2

Ridge Hill 24 COM5

Ridge Hill 25 PSB2

Lark Stoke 26 PSB1

Ridge Hill 27 COM 6

Ridge Hill 28 PSB1

Lark Stoke 30 PSB3

So PSB 3 will be found first from Ridge Hill and then PSB 2 from Larl Stoke. A duplicate for PSB 2 is next found from Ridge Hill on UHF 25, this MUX is already stored from Lark Stoke so all the channels on this multiplex get 800 plus lcn’s.

I’ll leave it readers to figure out where the other MUX channels finish up

JohnH77 – 3 minutes ago  » 

Graham

As you see we are in violent agreement. I was editing my post to

Quote:

6 Check you have no 800 numbered stations. Doing a manual tune ensures you do not have any.

while you were posting yours

Off topic: Do we have any definite answer to whether the EPG gets messed up if you have one station (eg C4) from a main transmitter and another of that same station (another C4) as an 800 number from a repeater or other main transmitter?

It doesn’t matter if the source is a relay of a main transmitter or the main transmitter itself. Relays use different channel UHF channel numbers (rebroadcast using a different carrier) and usually change from Horizontal to Vertical polarisation to assist with the aerial rejecting unwanted breakthrough from the parent transmitter. So in effect each relay is a different transmitter re the epg.

It’s not so much the transmitter that’s the issue but the complications of getting series/programme CRIDS and accurate recording signals for the same content from multiple lcn’s.

The same applies re the UH channel range of each transmitter.

In the table I provided Lark Stoke is a relay of Sutton Coldfield and in fact shares it’s UHF channels with Bromsgrove (and if I remember correctly the Wrekin). The 3 transmitters form a SFN.

https://en.wikipedia.org/wiki/Single-frequency_network

From your post:

1 All looks OK

2. The Humax has a very sensitive tuner which can be overloaded if you are close to the transmitter so buy an attenuator and try it.

See Variable Attenuator, Black (or Black/Silver colour, identical item) – Alters & varies Television signal

at https://www.amazon.co.uk/Variable-Attenuator-Silver-colour-identical-Multi/dp/B000LB0QC0/ref=sr_1_11?adgrpid=54796173004&hvadid=259058072812&hvdev=c&hvlocphy=9045647&hvnetw=g&hvpos=1t1&hvqmt=e&hvrand=14757891325792507335&hvtargid=kwd-310685949498&keywords=tv+attenuator&qid=1553096696&s=gateway&sr=8-11&tag=googhydr-21

or

Philex Variable TV Signal Attenuator

at https://www.amazon.co.uk/dp/B00L24G962/ref=dp_cerb_1. They are only a few pounds.

Please tell us your full postcode if you want more appropriate advice.

Jenonnet – 6 minutes ago  » 

Thank you so much for all your help and suggestions. Unfortunately I don’t really understand a lot of it, at 68 years old is a bit confusing to get your head round.

I don’t know how to tell which way the aerial should be pointing but it must be ok because when it’s connected straight to the TV all the channels work perfectly, it’s only when it’s connected to the humax box that I have the problems with the BBC channels. So that tells me the aerial is in the correct location and pointing the right way, otherwise the problems would be the same when connected straight to the TV. It’s always worked very well when connected straight from the aerial to the TV and all the channels worked perfectly well. That being the case, would I be right in thinking it has to be something to do with the box and not the aerial?

The best clue you have is looking at your neighbours aerials. If they have the elements horizontal they are likely to be pointing at a main power transmitter, if vertical one of the relay transmitters served by the main power transmitter. Your aerial should point the same way and match the vertical/horizontal alignment.

If you know how to grab a copy of window, then best plan is to fill in your postcode and house number and tick the detailed view here Don’t forget the detailed view..

At least tell us the colour of the reception boxes (green is best). and name of the transmitter at the top of the list.

In the table at the top of the list alongside the top transmitter it will tell you the distance from the transmitter and the compass bearing (direction), If you can post these as well especially the distance.

This is my result for the Sutton Coldfield Transmitter. Note the green results except for the lower power COM7 and COM 8 mux.

It possible your transmitter has recently changed the frequency of the Multiplex to value your aerial is not suitable to receive. If so you might be able to get it fixed for free if your only source of TV reception is by your aerial.

If you are close to a main power transmitter it’s possible the more sensitive tuners in the Humax are being overloaded by too high a signal which the TV tuner can cope with.

In this event a cheap adjustable box connected to the Aerial coax can reduce the level.

[attachment=71803,1236]

Suitable attenuator

Unplug the aerial and connect it to the matching socket on the attenuator. The other connector should plug in to the aerial socket on the Humax box.

Tune to a channel you can watch say a HD one.

Press the Freeview play button move to settings and press OK

Move to channel settings and right to signal test and press OK

You should see two values for tuner 1, one signal strength and the other signal quality (quality is the most important it should be 100% and steady).

Reduce the signal strength watching the quality doesn’t go down.

Tune to a channel you are having problems with. Find the lowest signal strength before the quality starts to drop. Increase a bit to give some margin.

Can you now watch all the channels ?

Jenonnet – 2 minutes ago  » 

Thank you both so much. I will purchase an attenuator and follow your instructions then report back.

I emailed Humax support days ago but haven’t heard a thing yet, so I’m really pleased I’ve got some good advice from you all on here, it’s much appreciated.

If you need to manual tune to Waltham post again, there is more info you need.

1 How to delete all your existing Radio and TV channels and start with none,

2 Some Mux require the modulation settings to be set to DVB-T and others (for Waltham BBC-HD, COM 7 and COM 8 to DVB-T2).