Class D amplifier as RF current generator

[dmills]

Any efficient amplifier can be blown-up by large reflected power from a resonant load.

An alternative IS, as Dan says, to put 90% of your power in a big resistor, tapped so maybe 10% of power goes to a happy load, and no huge hunks of reflected power can pass back to the amplifier. For your system, use a 600W 50r resistor in series with a 25W 2r resistor, your L-C tapped across the 2r.

I am not sure I would do it that way, but instead use a switched 10db 50 ohm pad (50 ohms in and out) so that during tune up the amplifier sees negligible reflected power but in operation you get full power into the load.

Of course if you can tolerate less then full power a 3 or 6db 50 ohm pad between the amp and the matching transformer left in circuit full time will provide substantial protection to the amplifier at the cost of 500 or 750W of waste heat and only 500 or 250W being delivered to the load.

73 Dan.