Every time someone has asked an extension cord question, the answers have always leaned toward "keep it short". I especially recall several answers to that question relative to 110V MIG units where the advice was "plug it into the wall..". Since I acquired my MM135 last August, I've pretty much run it on a 12/3 x 100' cord that is always plugged in. It's been my "convenience cord" forever in the Gadget Garage. Seemed to work OK, too. I've said that in a lot of posts about cords.
Yesterday, I wanted to weld the 1.5" x .125" legs onto my 2" x .250" frame for the chop saw table. The 100 footer was pulled outside for some lamps I was using to dry paint, so I grabbed a 25' 12/3 off the wall and plugged the 135 into it. When I struck the arc for the first time, I heard something different. Sounded like a LOT of bacon frying on high heat. Looked at the welder - same settings I usually use. So, I tacked up a leg and welded it in place. Larger HAZ than usual, and it looked like a better weld.
You know what's next - got the 100' cord and plugged into it; went for the second leg. Amazing!!! The welder performs SIGNIGICANTLY better on the short cord.
Can I have an ear of corn with this bird??