I have an HX-50 sitting in the "to do" pile. They are a neat looking transmitter. After looking at the skizmatic, I think they could be made into a pretty versatile low powered exciter for linear AM service. I think they will make somewhere around 10-15w of DSB am.
I will eventually post my findings here on AMfone when I find that mystical, elusive thing called "a round tuit"
The Slab Bacon