How do I solder splice awg #6 wire to Amphenol (T) Ten-6 coax cable to use as a 1/2 wave dipole cb antenna?

I've tried a soldering gun@140 watts, but can't seem to get the awg#6 hot fast enough, to get the solder going. I would like to insert the braided (unbraided then hand twisted) coax outer mesh copper shield, and its center conductor, each into two separate awg#6 cable lengths (both halves of the dipole antenna), like a pencil into a sharpener. I keep getting cold welds though I've tried different types of solder and SP-30 paste flux. The soldering gun (140 watts) gets the wire hot but not enough it seems, though I can feel the heat traveling down the wire. How can I get this heavy gauge wire to accept the flux for a good splice (Electrical/Mechanical), before I melt or crystallize the insulator within the thinner coax cable? Would this give the best type of connection? Is awg#6 "too big" for use as a dipole antenna? Lastly, is there such a thing as a 5/8 wave homebrew dipole (horizontal) for use on both 10 and 11 meter band?