I like to record opera from Radio 3 but the 80 minute limit on mini
disks is a bit limiting.

Got a Nicam vcr? The sound quality's pretty good, though you're
unlikely to be able to bypass AVC.

Or record to your computer. If you're using Windows XP with NTFS file
system, the filesize limit in FAT32 won't be a factor. Do a test
recording first, just to be sure.