I am using Phone Action - set Radio on/off to control the radio. Which seems to be working on my nexus 7 (2013). I see the connection drop when I select off.
I have a tasker program that toggles this setting because I use wifi most of the time and dont really want to waste battery, etc.
What I want is some way to know the state of the radio so I can do tasks based on whether it is on or off as opposed to checking for a 3g connection, I really want the radio on/off state.