Pineapple standards converter.

[ppppenguin]

There are many ways to make a modulator. The modern method is software defined radio. I did a quick and dirty experiment with an FPGA and DAC . Just a 1kHz sine wave on a 15MHz carrier but it was proof of principle. Frank Cuffe has also done some experiments.

I don't know if anyone has used one of the commercially available SDRs to do 405.

One thing that should be possible with SDR is vestigial sideband. If taking DIY approach in FPGA the Weaver or 3rd method for making SSB can be adapted for VSB.