Biggest parameters to watch are gate charge, input capacitance, and turn-off time.
Every power MOSFET will have a max frequency at which the gain falls to unity.
That is, the power out will equal the power input.
The 7530 seems to have roughly a four-to-one power gain, so that "unity gain" frequency is above 27 MHz.
And a great many of the high-power MOSFETs will have an upper frequency limit of a few MHz or maybe ten. Not so useful at 27.
And that's the tricky part. The published specs don't reveal this directly.
But it's related to "Gate charge", "Fall time", or turnoff time and "Miller capacitance".
Still haven't learned how to translate the specs they give you for a MOSFET they sell to use as an on/off switch to specs that will predict RF performance.
And if you have a gadget that measures gate charge and Miller capacitance, that would be cool.
Just finding a 7530 that's not blown out would permit measurement of the gate capacitance. Shouldn't be too tricky to set up that one with a normal capacitance meter.
Would give you a number you can compare to the published specs for a possible substitute.
Pretty sure Eric won't be telling us what the original type number was for that part any time soon.
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