Pavel, I tried the BTECH.py file you posted to the KT8900 group and received the same error. I am going to see if I can find a 32bit system around here to run portmon on and do a data capture. May be a day or two.
I have also tried it both in frequency mode and in channel mode, as the Sainsonic gt-890, Btech uv-2501, and as the Waccom Mini-8900, as well as the QYT KT8900 with the exact same results.
Attached is the debug.log from chirp
Frank Ketterman
AC0XV
Molon Labe!