[Amps] Power transformer

[Ku4uk at aol.com]

I have an old Berkshire Transformer BTC-4905 It's putting out 3000 v on  110 
volt. But want to run it on 220 v. The way it's wired now. the two out side 
wires were the wires  being used  for what I thought was 220 v with the two 
wires in the center tied together. However when I put 220 v on the two out 
side leads I only get  about fifteen hundred volts. Any good tips on how to 
check the windings ? Are anyone know about this transformer? Thanks   Leon 
ku4uk at aol.com