I have a Trailblazer 302 (model just before the 302 air pac) I am trying to TIG off off of it. I can TIG carbon steel great but when I go over to Aluminum on AC it just arcs a flaze with no heat and burns out the tungsten. Im using 2% thorated. Some one told me that I need a frequencey box but i thin this machine has it built in. Any suggestions?