Now you will hear the inactivity alarm.. Loud and Clear..

About the total radio ON timer. I believe you have a timer in the "STAT2" menu. Press and hold the menu button, a popup will come up, scroll down to "Statistics" then move right twice (I think), and at the top of the screen there is a redio ON timer.
I don't think there is an option to log it though.. Perhaps ask Mike if he can add it as an option..

João