hawhill is right.I am telling from my experience.The voltage in Tx Rx was 2.8v when I measured and everybody here talks about 1.8v.As I said you might not need the adapter you need an usb cable and the instructions here.
https://www.mobileread.com/forums/sho...0&postcount=25
When you hit 3 do it from the developers menu alt+E=3 give password and continue from usb in Linux.Maybe I am wrong as I typed from the hyperterminal in the serial adapter but I think I understand the process now.I followed this instructions and was success.In the end I ended up spending the same money as buying a used one in Craig list buy the fun it was worth it.