This Collins 516F-2 DUAL PRIMARY Power Transformer, is custom made in the USA, for a 120/230/240 VAC 50/60 hz Primary. The secondary voltages are the same as factory specifications.NOTE: This modern Transformer is made for use with Solid State Rectifiers. There are no taps for the 5 volt filaments on the 5U4 and 5R4, so solid state replacements must be used. The slightly increased voltage due to the use of solid state rectifiers is very slight and should not cause a problem. The saturation of the transformer with the increased current of the 5 volt filaments would be more of a detriment. This will allow you to use your Collins 516F-2 Power supply in virtually any country. Depending on your line voltage, you can select between the three color coded primary wires.The transformer uses Grain Oriented steel for the core or M-6 as the industry refers to it. This will make the transformer run much cooler than regular steel and will allow operation on 50 or 60 hzIt is more expensive to build but is of the highest quality.There were very few 516F-2 Power supplies made with a dual 120 / 240 volt AC primary so this is a great find!This is an exact drop in transformer with the exact same mounting hole so there is no need for any modifications.There is a sheet included with each transformer with the color codes and voltages of the wires.I have only a limited number of these transformers available so please do not hesitate to order.