It might be a good idea to mention SDR latency in a message that appears during the VarAC installation process. I've run into several hams using Flex and other SDR transceivers who were not aware that the issues they were experiencing with VarAC were due to latency. I've noticed that the TX/RX collisions that occur due to latency are usually detectable by the receiving station working the ham with an SDR and I usually send an email to let them know what the potential issue might be.
The other alternative would be to have Jose modify the VARA modem.
I use 600Hz filter on my 6500, only ever had issues when connecting to a SunSDR, but my 7300 also had issues with the Sun. But the new VARA HF and VarAC has made this an issue of the past.
Tony and I just a QSO and all seemed to go well, need to test these changes another day or two then will post the complete changes in Win11 I have done which seems to have helped, these should also apply to windows 10 as well. Thanks, Tony, for the test and qso
My rate has jumped some 80% + percent since we worked with those changes Gary. One Thing I have found out is Windows 11 has some issues with Audio Latency! I am currently using 11 and can verify that! I have made some changes with some registry settings and a few other tweaks which has helped even more. Had a nice chat earlier today with Russ in Florida for about 10 minutes or so and things went well here. I'm using A SunSDR2DX , with Winturd11. Key thing would be to ask the other user if that have upgraded to 4.5.5? if there still on 4.5.0 it will certainly have a bit more latency for SDR rigs. One thing I also suggest if your using VAC (virtual Audio Cable) with windows 11 try and use the WASAPI drivers and not the MME or other variants- here is a good article regarding this audio latency and win10 and win11 Low Latency Audio - Windows drivers | Microsoft Docs
The changes from VARA HF 4.5.0 to 4.5.5 were to address latency issues with SDR's. You do not see versions 4.5.1 to 4.5.4 in Jose's change log as several of us were beta testing the timing issues with the help of Irad. There were also some beta VarAC before 3.0.2 to help with this.
Because of this we now have several Flex 6xxx, Flex 5000 and SunSDR's now able to do SDR to SDR connects with some great results.
I am having no issues at all with my Flex 6500, and I have made a few QSO's.
Who is still having an issue?