Hey Joe, I don't have experience with the Hi-Freq box you mentioned but about 15yrs ago I use a lincoln Hi-Freq box for a bullet whole patch in a local Fire Truck. I was louder than what I was used to in a typical machine but it did the trick for the bullet whold, however I have my doubts about quality consistant welds, weld after weld.
If you find a Hi-Freq box that your're impressed with please let me know, Iwould like to have one for my Lincoln Ranger 250 GXT portable machine.
Lincoln 250 GXT
Lincoln 225 Buzz Box
Miller 250 Syncrowave
WeldCraft Flex V-17 for Linc. 250
WeldCraft water cooled for Syncro.
Victor (Baby) cuttin