Yes, I understand the ironless / transformerless concept. I also plan to use no transformers (step-up or step-down) or inductors in my design.

An advantage of DDS is that it is programmed via SPI, so a jumper change or RS232 command could make changes to waveform shape and frequency.

Pulse transformers and driver ICs appear to cost about the same here in Midwest US. I chose the driver ICs because they could be driven with logic level inputs regardless of the FET design.

It looks like more research money is going into 250V and 600V FETs and IGBTs than into any other voltage ratings, so that's where I have chosen to focus my designs.

Do you anticipate problems with running a system like this continuously (for months or years at a time)? Even if the FETs were well heatsinked and stay cool, I would anticipate continuous operation would degrade their lifetime.

Good luck guys.

Bryan