How can I keep the radio on in my 2002 chevy silverado?

[cody]

I have an '02 chevy silverado and I work out of it all the time and I like to put the windows down and leave the radio on but with the feature it has for not draining the battery, the accessory power cuts off after a certain amount of time and I have to turn the key to turn it back on. I was wondering if there was any way that I could wire up constant power to the radio by either running a fused wire from the battery or another 12v always on wire in the truck that way i would not need a key for radio. The wire going to the radio would have a switch so it could be turned on or off without the key in the ignition.

Thanks for any help.