Which model did you get and what was the price? What is the voltage at the electrodes, ac or dc? What is the amperage through the cables? Is there a tech sheet with a schematic?
I'm going to attempt to make a brazer out of a rewound microwave oven transformer or two. I experimented with one MOT, two wraps of an old battery jumper cable as the secondary. I got about 3 volts from the cable, and 12 amps through the primary, the secondary amperage was too high for my meter to measure. I tried it on 1/4 inch copper, it got hot enough to melt plumbing solder but not hot enough to melt 45% silver brazing rod. A third wrap of the secondary raised the voltage but caused too much amperage through the primary. The cable got really hot and eventually shorted out at the transformer. I'm thinking maybe a second transformer with some way to limit the amperage might do it.