TIS with 696

[mcattell]

I've connected the GTX330 Transponder to the 696 serial input but not sure how to tell if it's working. The 696 is set-up for TIS and indicates that it is waiting for data on that port. From reading the 330 manual it may not be sending a TIS stream if a valid stream isn't available. But I'd still like to know if everthing is connected correctly now while I can still easily get to it instead of waiting until I fly the airplane. Does anyone know if there's a way to test this connection without a good signal to the transponder? I can actually see radar sweeps when I enable the transponder but I don't want to run it too long and get a visit from the FAA. I could have a friend circle the house in their airplane but that may not work if I can't get a solid signal in the shop. There must be an easier way. Neither the 696 nor the 330 manuals were of much help on this matter.