Only an 18 year old thread but the M2057 was only made by GE in Owensboro, Kentucky. The M2057 was designed from the start as a RF amplifying tube and not a TV sweep tube. GE first developed the tube labeling it as the Y2057 and you will still find some M2057's labeled Y2057. The (M) in M2057 comes from the Maco company who was integral in the birth of the M2057 to begin with and GE custom labeled many of the M2057's MACO.