One of our esteemed Beta testers developed a cable that connects the Hardrock-50 ACC port to the Flex-1500's Flexwire I/O (see Hardrock-50 - Flex-1500 PTT canle.pdf below). We now support automatic band change with PowerSDR software. You will need firmware version 2.0B or higher running in the HR50 so upgrade the firmware if necessary. If you amp is S/N 1199 or lower you will need to modify the rear panel PCB as described in the Band Switching Modifications V2.pdf below. Leave the HR50 connected to the computer's USB port.
When you are updating the firmware, remember the Comm Port number that the HR50 enumerates as because we will need it in the next step. Start PowerSDR, select SETUP and click the CAT Control tab. On the CAT Control frame, select the port that the HR50 uses and if you haven't changed the HR50's USB Baud Rate in the menu, set the baud rate to 19200, then check the Allow Kenwood AI Command box, then the Enable CAT and click OK.
The HR50 will now follow the band selected by PowerSDr.
Starting in late 2017 we updated the rear panel to have an electrically isolated USB connection. This eliminates potential ground loops the cause problems with the Flex-1500 and other SDR's. If you have an older amp, we now provide a update kit to add isolated USB to any Hardrock-50.
https://hobbypcb.com/products/hf-radio/hardrock-50-rear-panel-kit