I am posting this here to help out fellow hams in a similar situation. Note that I am sticking to listing my particular settings, not getting into why it needs to be one way or another. You might also be interested in my other guide on using JT65 HF with a 590SG. Windows OS: Win 7 Be sure to install the Kenwood virtual COM port driver CP210x and save your radio settings with ARCP590G in case you want to go back. Both are free downloads from the Kenwood download page. FLDIGI: version 3.22.01 Radio firmware version: 1.01 (now is a good time to update. Be sure to follow the Kenwood update instructions precisely!) The radio is connected to the PC with just one USB cable. Go into Control Panel, Hardware and Sound, Device Manager and take note of the COM port of Silicon Labe 210x USB to UART driver under Ports. If there is a yellow exclamation mark at that entry the driver is not working right for whatever reason. Then it gets tricky and you will have to experiment with removing, reinstalling the driver. Sometimes a reboot helps. It's Windows, what can I say ;-) Pertinent radio settings (menu number:value) ============================ 77:50 76:ON 72:4 71:3 70:FRONT 69:USB 68:38400 67:9600 PROC: Off DATA: Off AGC: F RX & TX EQUALIZER: Off FLDIGI SETTINGS =========== CONFIGURE - SOUND CARD ================= SOUND INPUT DEVICE - SOUND OUTPUT DEVICE USB AUDIO - USB AUDIO (exact name may vary) PORT AUDIO: CHECKED CONFIGURE - RIG CONTROL / HARDWARE PTT ============================= PTT ON RIGHT AUDIO CHANNEL: CHECKED (IMPORTANT!) DEVICE: ENTER COM PORT NUMBER FROM DEVICE MANAGER'S PORT FOR THE VIRTUAL COM PORT DRIVER USE RTS: CHECKED USE SEPARATE SERIAL PORT PTT: CHECKED (MAY NOT MATTER) CONFIGURE - RIGCAT ============== RIG DESCRIPTION FILE: TS-590S.XML (DOWNLOAD FROM THE FLDIGI WEBSITE. http://www.w1hkj.com/xmlarchives.html ) USE RIGCAT: CHECKED DEVICE: COM PORT AS MENTIONED ABOVE BAUD RATE: 38400 STOP BITS: 1 CAT COMMAND FOR PTT: CHECKED DTR +12V: CHECKED RTS/CTS FLOW CONTROL: CHECKED Press the initialize button and see if FLDIGI now shows the correct radio frequency. If not, the COM port (or other settings) may not be right. Note that FLDIGI may work OK for RX/TX even if the cat commands are not functional. If you are also running HRD and/or other software that needs a COM port the setup gets more complicated. That is is beyond the scope of this guide. This guide is just for getting Fldigi to work with your radio. There are a bunch of settings to adjust the program for optimal use, the manual and google is your friend. If somebody can post the equivalent menu numbers for a 590S this guide might be of use for that radio as well. Good luck and have fun!