Using SunSDR2 DX with the stealth loop.
Upgrade the ATU to v4.0.9
Connect null modem cable to the ATU and computer
Configure ATU to use CAT MODE 3
In SunSDR CAT menu enable ECATv1
Now the loop is tuning either by FULL AUTO, SEMI AUTO or DISABLED depending on what you want.
73 de LA3QMA
Just want to inform that i have made a program for SunSDR (Expert Electronics)
Based on CAT MODE 3 CML_409 and SunSDR2 or SunSDR3 you can connect a RS232 Serial Nullmodem Cable to your ATU and to a computer.
Start my software with parameters like COMPort and i.e localhost:50001
Now when you change frequency on the SDR software it's sending the QSY information to the ATU.