Hi, I make a CW serial interface, I using this interface with other software, and I want to use with a DX base 2006, I use a DTR PIN, but doesn’t work!! On circuit I use a 4N35, a one diode, and one resistor . Best 73 de IZ7AUH Frank Francesco Giacoia, IZ7AUH Strange Radio Team www.strangeradioteam.com iz7auh at strangeradioteam.com