I have a DEC LK250 in the cupboard. Basically it's like the LK201, except with PS/2 connectivity. When I didn't have any computers with PS/2 ports any more, I bought a USB converter, but it never worked properly. Possibly the antique beast required too much current.
That's certainly the case with my current clacky keboard, a budget ADX gaming one. I've had to use a powered hub for it (there's a LED for every key). But as well as decent keyswitches, the key legends are moulded in, not painted on. I hate it when they wear off.