I have an old filament transformer removed from a homebrew amp that had (2) 4-1000A tubes in it. It is 215VAC input and has 2 separate secondaries 7.5VAC @ 26 amps. I assume both could be placed in parallel for a 3CX3000 tube. Transformer is heavy, price is $75 shipped to your door in the U.S. Tnx & 73, Jim