Just because a radio is TSO in USA, do not presume that it will be ok over here, for example some VAL radios are not approved here in the UK. Call the CAA they have an approved list or will investigate the radio for you, I have the number somewhere if it is needed, but you can get the info from the main CAA number and ask for radio dept. The PFA only approve CAA approved radio's, it is to do with band width transmission i.e the transmission not leaking onto another frequency.
Will.