Thanks for that smcm, handy info about the 5mm cable and also the LMR-400, I'll phone the marine electronics place in the morning and see if they have 5mm or one of the other places in town as that will let me work with it at the weekend. I am only trying the supplied antenna on shed roof if it is a nice day (Non starter up here then) Just a case of siting it on for as long as it takes me to see what kind of coverage I can get. This is just so I have some idea as to site of outside aerial, I think it will prob end up on pole on gable of house. Loft space seems like an easy option if I could get longer USB cable.
Sandy