I took my Vans RV-10 up on its first flight this past Saturday. I was talking to ATC on their frequency and to my father on the ground with a handheld tuned to 123.45 ('fingers'). Mostly I was keeping my father informed as to what I was doing and how the plane was behaving, but 10 minutes in someone broke in with a curt 'Get off this frequency!' It's my understanding that the frequency range 123.325 to 123.475 is reserved for civilian flight testing, so I'm not sure who I was intruding on or if that person had any business telling me what he did. What's the proper frequency I should be using to communicate with my ground crew while flight testing?