It took me a week to figure this out so it's good to document for my own future reference.
First off it I tried the WSPR 2.0 software for Windows from K1JT and the CAT control would not respond at all to the Flex radio and PowerSDR.
When I switched to the WSJT-X software (ver 1.7.0) from K1JT that did work with CAT and appears to be a much more versatile program working with many other modes like JT65 (not just WSPR).
Flex Radio settings under PowerSDR v2.7.2
- 2x VAC lines active in settings. Input VAC1, Output VAC2, Sample Rate 48000
- 2x CAT COM ports active. COM10 for primary CAT, COM12 for PTT.
- ATU = On
- AF = 100
- AGC-T = 120
- Drive = 1 or 5 watts depending on output choice
- SQL = -160
- DIGU mode selected for all bands being used by WSPR
- 4k filter selected for all bands being used by WSPR
- Virtual Audio Cable software installed and configured for 1 pair of cables (1 and 2)
- vspMgr Virtual COM Ports installed and configured for 2 pairs (10-11) (12-13)
- Start Menu to Control Panel to Sound
- Line 1 = 48000 Hz, Level 75
- Line 2 = 48000 Hz, Level 75
- Callsign = VA7AEJ
- My Grid = DO00mf
- Rig = Kenwood TS-2000
- Serial Port = COM11
- Baud Rate 115200
- PTT Method = CAT - COM13
- Mode = None (other choices cause CAT errors)
- Split operation - None (other choices cause CAT errors)
- Soundcard Input = Line 2 - Mono
- Soundcard Output = Line 1 - Mono
- Enable TX = On
- Input dB scale = drag slider until audio levels sit at approx 30db
- Pwr output = leave at full (top)
- Output level = 30 dBm 1 W or 37 dBm 5 W
Issue = Waterfall in WSJT-X displays solid red vertical lines and makes no contacts.
Answer = No audio reaching the WSJT software, check that VAC is enabled in PowerSDR.