I'd like to experiment with the gnuradio nrsc5 (HD-Radio) encoder module, and I'm wondering if it would be practical to build a rudimentary I/Q modulator on a breadboard. Or would the output of something like that be so non-linear that it's just not practical? I've got no RF design experience, so I'm just spit-balling and hoping somebody more experienced will chime in.
Does that sound naive? Or is there a version of the Chinese ready-made DDS VFO modules that will already do what I'm talking about, and I just don't realize it?
I was thinking of just taking the I and Q output from a sound card and feeding them into a pair of MC1496 balanced modulators, then combining that into some sort of output transformer, maybe with an op-amp depending on what the output levels are like. I'm sure it will need some filtering to remove all the nasties created by all the mixing and combining, and that will have to be trial and error. Initially, I'd probably use a 2-channel signal generator for the quadrature carriers, but if it works like I hope it will, I'd probably add a VFO with some type of phase shift circuit on one branch.
I've seen several articles and YouTube videos about doing demodulation in this way, so I just assume the reverse would work.