tech request: school us on tig welding?

I was looking into this a while ago, and I was told that to use an arc-welder as a TIG power source for welding steel, it has to be a DC arc welder. A lot of cheaper arc welders are AC only.

That hasn't been mentioned in this thread yet, so can anyone confirm if it is true ?

 

I have a 140 amp tig and i really like it together with a self darkening helmet it is a pleasure to use . No noise no sparks no hot bits running down the gap in your shoes no fumes no smoke need I go on mine is lift start and a breeze to use it sure pumps out some heat when you wind it up on the thick stuff
****** gas company are a pack of rogues tho :-(