I usually wrap the barrel and threads of the N connector with several layers of paper, and hold it in a small vise. The paper protects the threads and slows heat loss to the vise while soldering.

Solder the shield of the .141 coax balun to the connector as shown.

Next, trim the solder cup of the N connector a bit, and solder one end of the dipole into it. Making a small bend into the cup of the pin is helpful.

Last, bend the center conductors of the balun under and around the ends of the dipole and solder as shown. Be careful to leave a small gap between the outer conductor of the balun and the ends of the dipole (about 2 mm).