"T i m" wrote in message
...
(How often / easy is that to happen and under what circumstances would
you say? I mean, don't the TV's often ask for your location / 'Region
to (presumably) know what range of frequencies it should be looking
for?)

If 'automatic' tuning doesn't work because it can be confused by which
transmitter(s?) to use, would that mean tuning it manually and what
typically happens after when a re-tune is required?

I imagine it depends on TV firmware as to whether the TV asks for a postcode
to tune to the muxes on transmitter that is designated for that postcode, or
whether it just does a scan from UHF 21 to UHF 68 to see what it can find.
Usually you end up with all the muxes from the *same* transmitter, but I
have seen cases when you get a mixtu before the aerial at my parents'
holiday cottage was upgraded (presumably from grouped to wideband), there
were problems that an auto scan would pick up some muxes from Bilsdale (the
"correct" transmitter for that locality) and some muxes from Emley Moor
(which is miles away over several hills). Until we had the aerial changed
and a kink in the cable that fed the aerial wall-box repaired, I had to
manually tune each mux to prevent it finding Emley. I presume, because of
the old aerial's selective gain in different parts of the UHF spectrum, some
Emley muxes were actually stronger than some Bilsdale ones. There is also
the issue of atmospheric "lift" causing distant signals to be stronger at
certain times, which is a problem if you retune at that time.