An important update to this post - as it turns out, the sound output format change was a red herring - that is not the solution. The solution that provided flawless ongoing operation with my station was to revoke exclusive control of the soundcard device - see the attached image for the setting that I unchecked within Windows Sound Control Panel for my SignaLink USB output. I hope this helps someone! Station is: Kenwood TS-570D, Signalink USB, HRD 6.8.0.372, VSPE 1.3.6.970, VarAC 8.2.0, Windows 10 Pro. I have PTT configured via VOX with no problems. Frequency control is via CAT with Kenwood Generic, connected to a virtual serial port created within VSPE. See my other post regarding this: https://www.varac-hamradio.com/forum/varac-hf-discussion-forum/hrd-varac-vspe-rig-control-logging-ts-570d-signalink

Awesome, thanks, Irad. Your reply helps me better understand a possible reason that I was having trouble with CAT PTT control while using HRD. I have things configured now to use VOX for PTT and it is working flawlessly for me. One thing that I did within Windows that seemed to solve a frustrating problem that I was having, in which I would have no RF output during PTT/TX triggering, was that I revoked exclusive app-control of the sound device (in my case a Signalink USB interface), as well as ensuring I do not have HRD's DM780 running at the same time as VarAC. Image below shows the config setting within Windows Sound Control Panel for the device. Station is: Kenwood TS-570D, Signalink USB, HRD 6.8.0.372, VSPE 1.3.6.970, VarAC 8.2.0, Windows 10 Pro. Thanks for all of your excellent effort to make your awesome VarAC software available & creating a new fun mode of communication! Now that I have v.8.2.0 working well for my station, I am going to try out the update. 73 de KG9NI

Excellent! Thanks!

The solution for me was to change the interface/soundcard output sound format to 16-bit 44100Hz CD quality sound. That was all it took! Good luck!

Hi Irad - I am also very interested in an eventual solution that allows VarAC and HRD to play nicely together. If I can be of any assistance to you as an intermediary, I will be happy to try to help. 73 de KG9NI