I have been using an SSR but it limits the operating frequency and feels unneeded. The SSR being used right now is this one from automation direct
The point of not using an SSR would be to achieve a higher frequency than 50-60Hz, which is what the data sheet lists as the operating frequency for them.
This would also be a way to save costs by not requiring a separate circuit to drive a 48v device, either by an SSR or the mosfet selection I'm proposing.
I do not understand your concerns.
For a bed heater the frequency range you listed is fine. Bed heaters rated for line voltage (110/220 VAC) are usually more powerful which is a good thing.
Since the SSR connects directly to the bed heater output on the Duet it is about as simple as it can be.
What do think you would improve by doing what you propose?
Hi Fred. I never said I wanted to be driving a bed heater from the V_bed line, but rather I wanted to drive 48v at a higher frequency (ideally 1-2khz range). This is an exploration at the possibility.