Can anyone tell me why all of my BBC digital channels have no signal at night or the early morning, but work again during the day!? thanks

This could be too much signal thanks to the Freeview retunes going on. Your aerial is more sensitive at some frequencies, so there's more signal power higher up the frequency range.

A simple and inexpensive diagnosis tool is a variable attenuator. The MA1620 on this page is perfect for that job:
Splitters amplified splitters and attenuators

It will give you a way to reduce the signal level at one TV without affecting the other TVs in the house.

sometimes you can have weaker signal, and pictures freeze...
it can be caused by bad weather, by thunderstorms, heavy rain....
you can't do anything about it, just get stronger antena....it can improve your gain from signal, but never for 100%

check to make sure there is no crack or liquid getting into your distributor cap.

I have run into this problem a couple of times, once a loose connection at the LNB, other times it has been due to moisture build up (dew) in the loose connections, check all connections from the LNB through the tuner, and any other devices involved (a line map maybe?) that will most likely resolve the problem.

Check for any damage to the cap or on the wiring if no damage is visable replace the cap.

You may lose some channels when you retune the TV as the channels have been rearranged. To locate them look at the EPG although you may still find that some channels are no longer available on FREEVIEW. See the following link for additional information

http://www.freeview.co.uk/_retuneinfo/

If the above process does not work then check the link above for additional information and also visit the accompanying site links below to find more information for your model of TV / FREEVIEW box.

For troubleshooting the retune procedure visit http://tvretune.co.uk/troubleshooting/

For specific model information visit http://tvretune.co.uk/productmanuals/

Hi, exact same problem. Can anyone help??

just solved the problem
with the variable attenator fitted i did a rescan still didnt work
but when i did a rescan to the restore factory settings it now works

First I would move the box closer to the booster (amplifier) if its furthest away from it. Do you have another box you can swap out in that location to see if the problem is the signal for some reason? I am not familiar with the boxes but, is it possible at 11 PM they are doing guide updates or possible software updates at that time? I know that here in the U.S. our two satelitte companies do guide and software updates but, those usually occur in the early morning hours of 2 AM. Hopefully that helps.

What brand of tv is it ? You could have a bad tuner or a change in the voltage supply line feeding the tuner . What type of antenna do you have ? outdoor or rabbit ears ? Also does it retain the channel line up or does it clear them as well ?