I need maximum transmission hence have to make something that supplies plenty of current.
Then none of the suggestions so far will work.
You need to feed the filtered PWM output into the gate of a FET with the load connected between the source and ground. Connect the drain to your 500mA capable power supply. The voltage does not matter but the higher it is then the hotter the FET will get because it will be running in linear mode and be burning off the power not used by your device.