Today I finally got the DECstation 5000/240 with a TURBOchannel Extender cable from the Mesa Electronics clearout back in May. Details here if anyone is interested: https://robs-old-computers.com/2017/07/15/decstation-5000240/
Unfortunately I didn't get a cable to connect the Extender to the main machine. I have a feeling they are hard to come by, does anyone have one that is surplus to requirements or know where I can get one? Thanks Rob
