I just resurrected an HP 58503A and have been using it successfully for the last few days with the GPSCon program. I would prefer to use Lady Heather, but can't seem to get it configured properly. My system is a Windows 10 PC with a USB to serial cable at COM3. The serial protocol on the 58503A is 9600,8,N,1. I've added /3 for the COM port to the startup command line. All other config file parameters are unchanged from the default. When I start LH it finds the 58503A and identifies it as a SCPI receiver, but then it hangs with no position data or time data, and the PC speaker chimes continuously at slightly slower than once per second. The only way to exit the program is to kill the process with the task manager. There are no other programs vying for the COM port. Any and all help is appreciated! Thanks, Stan