Just purchased CMT-G1BiP. Set up the FM and AM radio presets. seemed Ok but then noticed that when returning to the FM or AM function from other functions - notably the DAB or USB that had not correctly operated (DAB didn't lock to station or USB was 'Not Supported' the unit behaved as though there was no antenna (ie loud static/noise/hum). Found that I had to, leave the function selected, go fully into Standby and then turn back on before the unit accepted the antenna input. Is this a 'feature' of this unit or is unit faulty and needs returning to seller?