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6600 reboot required to correct WSJT FT8 distortion on Transmit

AG4Q Member ✭✭
edited April 2022 in DAX

My 6600 runs almost 24X7. After days with everything working great, FT8 transmit will be be badly distorted, occupying far too much bandwidth (perhaps up to 2 KHz). When this happens, rebooting the 6600 resolves the issue. Closing and restarting SSDR or WSJT does not resolve the problem.

Is this a known problem? Does anyone else have this problem?

Sometimes I get clicks in in the FT8 TX signal, but those are usually resolved by closing and reopening WSJT.

Best Answers

  • Bob K8RC
    Bob K8RC Member ✭✭✭
    Answer ✓

    I have the same problem.

    Try just shutting down DAX then immediately restarting it.

    That does the trick for me in far less time than it takes to reboot the radio.

  • Tim K9WX
    Tim K9WX Member ✭✭✭
    Answer ✓

    I have a similar problem from time to time, occurring after I have had SSDR running for multiple days.

    Here is my normal FT8 signal:

    And my corrupted FT8 signal:

    Flex has suggested a procedure that may help diagnose and correct this problem, see https://helpdesk.flexradio.com/hc/en-us/articles/202118698-Using-LatencyMon-to-collect-DPC-Latency-Data

    I have downloaded and installed Latency Monitor on a PC which I feel is as up to date as it can be in terms of BIOS, software drivers, OS etc. and find that I still get bad latency scores and a corrupted TX signal. Whether or not that is the cause of my problem is anyone's guess. So I have learned to live with it.

    Tim K9WX

  • bahillen
    bahillen Member ✭✭✭
    Answer ✓

    To recover from this you don’t need to shut down DAX or anything else. Just click the DAX TX button to off then back on. The issue is resolved for another few days.

    As a matter of operation I click the button every day or two and never a problem.

    The problem often for me was unless I was listening to the tx audio and heard the distortion or was looking at the waterfall I spew out 1500 watts of QRM.

    it seems that with all the software in our software and drivers resetting that function would be a quick fix.

    This may have been addressed and is in a next release. Wishful thinking. Hope my resolution works for all of you. Restarting DAX killed all of the wsjt information while off and on of Audio TX stream didn’t even miss the the QSO.


    Bill W9JJB


  • John KB4DU
    John KB4DU Member ✭✭✭✭

    Yes it’s a well known bug in Dax, has been for years. Flex claims it’s on the list, but like hundreds (or maybe thousands) of others, no effort to fix it. Just guessing, it’s a buffer overflow or somethng similar.

  • AG4Q
    AG4Q Member ✭✭

    Thanks everyone for the helpful comments.

    I now have an easier way to recover from the problem without shutting down the radio.

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