You need to go to the website http://www.digitaluk.co.uk/coveragechecker/ and enter your postcode and house number, tick the detailed view box to find out what you ought to be able to receive and from which transmitter.
That site tells me that Felixstowe will only give you "BBCA"* (UHF channel 45), "D3&4"* (51) and "BBCB HD"* (53). From these you will not be able to get BBC4 HD. You should be able to get BBC4, and be able to record it.
Sudbury has BBCA (44), D3&4 (41), BBCB HD (47) and others. You would not be able to get BBC4 HD from here. BBC4 should be available.
You mention getting BBC HD and ITV on UHF channel 28. I cannot find any reference to any transmitter close to you that broadcasts BBC HD on channel 28. There is a transmitter at Aldeburgh that has BBCA (28), D3&4 (23) and BBCB HD (25)
You say you can watch BBC4 live. Is this through the Humax or directly on your TV?
Do you know where you are getting the BBC HD channels from? Whilst watching a channel press OK then i+ on the remote and a box appears - the last line should start Ch53, or Ch47, or Ch25 (or maybe something else). You should be able to determine which transmitter you are using. You may then be able to manually tune BBCA and D3&4 for that transmitter.
( * BBCA - standard definition versions of BBC1, BBC2, BBC4, BBC News, BBC Parliament, CBBC, CBeebies, BBC RB 1 and radio;
D3&4 - standard def ITV, ITV2, ITV4, Channel 4 ,Film 4, E4, More 4, Channel 5 and a couple of "+1" channels;
BBC B HD - BBC1 HD, BBC2 HD, ITV HD, Channel 4 HD, Channel 5 HD, CBBC HD and Film 4+1 (not HD))
| Sat 12 Aug 2017 19:38:36
#5 |