Hi J69
see my below thread I had the same issue and it turned out to be the radio requiring GPS data before transmitting, i did want to hook the VHF to my GPS so I had to turn all the setting options to off and then turn on the options that i wanted that did not require GPS data and it worked perfectly after i did that. No where in my manual did it indicate the VHF would not transmit with the GPS not connected and the menus not turned off, it took me about 25 mins to turn every option to off and then turn them on 1 by 1 until the issue occurred again, very frustrating.
Re: lowrance Link 5 VHF radio
got it sorted today, went to the options menu and turned everything off one by one.
then started turning each option on one at a time, problem seemed to be the GPS Data option, once it was off the radio transmitted fine.
BigE