This provides c. 92% household coverage across the UK, but does not include smaller the relay transmitters, known as “Freeview Light” or “Freeview Lite”.
Quite simply Free Light is a reduced version of Freeview with significantly less TV stations than a full Freeview service, (around 15 channels, at last count!).
As of September 2022, channels that are on the same DTT multiplex as UK Radio Portal include:
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If you can received the above channels, then you should be able to receive UK Radio Portal on channel 277.