Zenith K731 - New Project - New Questions

Thank you BOTH on your replys. I have let it run for quite a while today about 4 or so hours and it's still chugging along. The volume shifts from time to time, only once getting way louder than it was when I first turned it on. Still no audio from AM though. Does this unit have to an external antenna or is internal one suffecient? I figure it needs an antenna to get maximum reception but I figured I could at least hear a local close oldie station without one.

Also, I remember a little about a friend messing with those old sweep tube amplifiers on the cb band. Every time he would mess with it, he bled down those huge capacitors eliminating a rather nasty shock. Is this needed with this particular radio?

Thanks again,
Mike