Sorry for the question, I figured it out the 50/60 Hz statement means that it will work in either 50 Hz or with 60 Hz since it is completely electronic and has no motor in the construction.
Many moons ago Mexico City and visinity was part of Compania de Luz y Fuerza Motriz, if my memory serves me right the original owners were British, they provided 110 Ac 50 cycles (that was what they called them) power being generated at the Necaxa dam.
The rest of Mexico was all 120 v 60 cycles from the Comicion Federal, as far as I remember, today Mexico City is 120 v 60Hz.
Thanks ya all for the info, at least now I know the peed of the dinamos.
navegator