dkl65:
plug a cable into an input then touch just the center conductor on the connector at the other end
What does that mean? Plug it into a wall outlet, set the radio to no particular channel, then touch the antenna? I want to do it as long as it causes no damage!
No, we are not plugging anything into the wall! I'll use a stereo receiver for example. Well go ahead and plug the receiver into the wall as usual to power it. Now most will have audio line inputs, probably several different ones that can be selected via a switch or something on the front panel. May be labeled CD or AUX or whatever. Typically some audio component will be connected to these inputs with an RCA cable like this: http://www.outletpc.com/c8206.html
So get a cable like that, turn the receiver on, turn the volume all the way down so the speakers don't get damaged, pick an input and plug the cable into it, select that input via the receiver's front panel. Now, touch only the center conductor on the end of the cable that's not plugged into the receiver and slowly turn the volume up. You should hear a buzz coming from the speakers when you touch the cable.