AB-15: How to unscrew stuck upper/lower halfs?

[A45WV]

I have a NOS unused AB-15 aux antenna base. Does anyone have any good methods to unscrew the bottom from the top half? Mine is stuck beyond hand tight (or at least my 60 yo hand tight?). Given the ceramic insulator, I don't want to put any tools near it.

[rickf]

If you have an old serpentine fan belt you can quickly and easily use that as a strap wrench to grip one half of the porcelain. Loop it around and then turn the part that is looped around in a clockwise direction around the antenna so that part of the belt is ticked under the rest of it. Now you have something you can really grip onto that will tighten onto the porcelain tighter as you pull tighter. But it is softer than the porcelain so it will not break it. It has been so long since I had mine apart I forget the mechanics of how they go together.