I've finally got FT8 working on my #trusdx! All it took was plugging it into a ~20 year old laptop. I'm running it via audio only, no CAT control. Even managed to make a contact! And I can see myself reported on PSKreporter.
The real reason that this works (I think) is because the T42 has separate headphone and mic jacks, rather than a combined TRRS jack. @conor pointed out a while ago that the splitter I was using with my other computer was probably the problem and he is most likely correct.
Made a few more FT8 contacts today. I'm limiting myself to <500mW for the time being as the #trusdx needs to see low SWR at full power (5W) to avoid cooking the finals and I don't have a tuner for it.
@N9DRB
After wrestling with those combi-plugs (headphone and mic in one) unsuccessfully, I got an external USB thingy. I shelled out some money and got myself a https://www.thomannmusic.com/behringer_u_phoria_um2.htm (from the German part of that company) and did not regret it. You may get away with cheaper stuff. (Now, my most recent rig has an USB soundcard built in.)
@conor