transformer design amd impedance matching

hi........i am ec student....
i want to make a transformer which can be work at 3 MHz frequency.....
primary voltage of 60v and secondary voltage of 12 v nd secondary current 1A....
here i/p signal of 1mhz and 3mhz pulses....
now my circuit works at 1mhz bt didnt work with 3 mhz........
at 1mhz i connected load impedance of 4 ohms my circuit works
bt when i connected to load impedance of 2 ohms ...........my circuit didnt work
so plz help me........
thank you.....
warm regards....rky