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Very Distorted Transmit SSB Signal on 6700

Fred, AB1OCFred, AB1OC Member
edited January 20 in FLEX-6000 Signature Series
I am seeing a great deal of distortion of the Tx signal when operating SSB audio on my 6700. I'm attaching an image of my Tx waveform from my waterfall which illustrates the problem -


It appears that the signal is badly "chopped up". I have had other stations monitor my signal on the air and confirm the problem. I am seeing this on all bands in SSB mode using either the direct microphone input, a PC audio input from my client PC and from my Maestro with a directly connected microphone. The radio has only a dummy load connected to the output with Tx power = 1 (minimum) or above. I have tried restarting both the DAX app, the client PC, and the radio (power cycle) but nothing seems to help. The radio just has a microphone, ethernet cable and a dummy load connected. The ethernet infrastructure here is wired GigE with a single, enterprise-grade switch between the radio and the client PC running SmartSDR. I am not sure how long this problem has been going on but I just recently noticed it. We are running SmartSDR v2.1.33.106 here.

Network diagnostics as follows -
Network Status: Excellent
Latency: 1 ms
Max Latency: 34 ms
0 packed dropped....

Please help as we have a remote GOTA event scheduled at a local Ham Fest here in a little over 1 week and we were planning to use the 6700/Meastro combination for our GOTA.


  • Mike-VA3MWMike-VA3MW FlexRadio Employee, Community Manager admin
    edited April 2019
    Hi Fred

    Thanks for the screen shot.

    Any idea when this started?

    I noticed that you have a profile of Torbie Remote Digital.  Can you try a different profile?  Maybe the default one?

    What are you using for a Mic?  What type of element?

    The one idea I have is to do an export on your profiles just to save them and a reset of the radio.  

    You do have the PC Audio link turned on.  Could it be a feedback loop in the sounds cards.  Does it go away with Monitor turned off and/or PC Audio also turned off?

    Your mode is also set to DIGU and not USB.  The more I look at this, you are in a digital mode and your description talks of being in SSB.


    FLEX-6700 and FLEX-6500

    1. Power off the radio
    2. Press and hold the OK button
    3. Momentarily press the Power button to start the radio
    4. Continue holding the OK button until the display counts down to 0, the Power LED turns WHITEand the CALIBRATING... the message is displayed.
    5. Allow the radio to continue booting normally.
  • Jim GilliamJim Gilliam Member
    edited April 2018

    Everyone should invest in a dummy load to eliminate one possible cause.

    Jim, K6QE

  • Fred, AB1OCFred, AB1OC Member
    edited April 2018
    Error on my part to leave radio in DIGU upper on this band. I did a Factory Reset on the radio. The microphone is a Yaesu MD-200 with a Dynamic Element. I have tried the HM microphone/maestro with the same result. Here is the Tx waveform with the PC Audio off after the factory reset in USB mode -


    If anything, the problem is worse.

  • Fred, AB1OCFred, AB1OC Member
    edited April 2018
    Radio is on a dummy load for the above demonstrations of the problem.
  • Fred, AB1OCFred, AB1OC Member
    edited April 2018
    I really just noticed this today. I did just expand the width of my signals so it may have been going on for awhile and I did not notice it because the display of my Tx signal was much narrower.
  • Fred, AB1OCFred, AB1OC Member
    edited April 2018
    Just switched to the Default Microphone and Tx profiles. That did not help.
  • Martin AA6EMartin AA6E Member ✭✭
    edited January 20
    Possible weird power supply trouble?  Try a different supply.  Check DC voltage, contacts.
  • Fred, AB1OCFred, AB1OC Member
    edited April 2018
    Tried running from a large Lipo battery - no improvement.
  • Mike-VA3MWMike-VA3MW FlexRadio Employee, Community Manager admin
    edited April 2019
    I have converted this to a HelpDesk support ticket.  If anyone else is experiencing an issue similar to this one, please submit a HelpDesk support ticket for issue resolution.

  • Hank WolflaHank Wolfla Member
    edited October 2018
    I have the same problem with my 6500.  This problem seems to hit many people, and so far I have not seen any formal response from Flex and a willingness to help.  Smart SDR license was a waste of my money for SSB.  Hank K9LZJ
  • Mike-VA3MWMike-VA3MW FlexRadio Employee, Community Manager admin
    edited April 2019
    Hi Hank, if it is an issue with many people, they have not reported it to us.   Moving from V1 to V2 would not have an impact on your transmitted audio.

    I would recommend that you run a test with the supplied hand Mic and see if have the same issue.  You can monitor yourself running in FDX on a second slice.   We do this to make sure we start with a simple setup and expand out from there.

    We do want to work with you on this, so if you find that you have this issue after the above test, please get a support ticket opened so we can work to resolve it.

    Let us know how you make out.  
  • N8SDRN8SDR Member
    edited October 2018
    What struck me as odd is why the mic gain is cranked as high as it is with  that mic.. 

  • Bill -VA3WTBBill -VA3WTB Member ✭✭✭
    edited October 2018
    Looks like simple distortion to me. The EQ settings are likely over driving the PROC, and the mic level is pining the 0 on mic level,,back it down so it peaks at -5 at the most.

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