Scott - many thanks for your very helpful post. If there was a thanks button facility on this forum, I'd click it!
I don't doubt there are real differences, e.g. between an entry level Clarke and a Portamig, and you help me understand what they might be. At some point, I hope to enhance one of my cheap MIG welders to see if I can turn it into something more like a Portamig.
Heavy-duty wire feeder - definitely
Copper transformer and choke windings - I don't doubt the better duty cycle but does copper really "make the weld more consistent" i.e. somehow better quality?
More power settings - 16 vs 4 or 6 - I can see the advantage here, and that would probably involve winding my own transformer, unless I could add a pre-transformer, like to take 240V AV down to, say, 180V AC before it even enters the MIG welder transformer. I might be able to add more adjustments within that pre-transformer.
Noise filtering - Caps on AC line and rectifier to surpress noise - I would certainly add these but I thought Malcolm said the Portamigs don't have capacitors.
You say that "adding caps to a MIG that was not designed for it will increase the minimum current significantly". How is a transformer 'designed to take capacitors, exactly? Could I build that factor into my pre-transformer or a revised reactor, perhaps?
Any MIG I use or modify/build MUST be able to weld thin metal. That would be its main application in my range of options. On anything heavier, I'm sure I'll be happy to continue using my arc welders.
