Welcome to the forum drw!
We usually don't answer questions in this section, but I will let you know about that one. For more info, please post a thread in the gyro section under helicopters.
You need a Rx with the 3GX, be it a full size Rx like the AR6210 or just a satellite plugged directly into the 3GX. If using satellites, you will control the gyro gain on channel 7. If you are using a full Rx, then you will use the Gear channel for the gyro gain. Hope this helps.