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Weird CW problem

Hi everybody.

I am a new user of SmartSDR and am experiencing a weird problem on CW. I use semi break-in with 500 ms delay, as I have always done on all my radios, and everything works fine with my Flex 6400, except...

Every time the radio goes into TX, it seems to still be receiving for maybe 100/200 milliseconds. This is really strange. To make myself clear, in the headphones I hear my first or first two CW characters together with the RX audio. Then the rx audio goes away and I continue normally with my CW sidetone.

I am sure I am doing something daft, and would appreciate any wisdom.

73 Pete MM0TWX


  • Pete Parisetti
    Pete Parisetti Member ✭✭

    Actually... I realise that when I key the transmitter with the MOX button, I still hear noise in the headphones, as if the receiver was still on, with the antenna disconnected. With the TUNE button that does not happen. Stranger and stranger....

  • KD0RC
    KD0RC Member, Super Elmer Moderator

    Hi Pete, I cannot recreate this issue with my Flex 6400 running V I do get the same effect when I click the MOX button. It might be a good thing to try a factory reset. First, export your profiles to be sure that they are safe, then do the reset (from the SmartSDR Software User Guide v3.x):

    FLEX-6300, FLEX-6400/M, FLEX-6600/M Reset Procedure

    With the radio powered off, press and hold down the power button until the Power LED blinks white, then release the power button. Allow the radio to continue booting normally.

  • KD0RC
    KD0RC Member, Super Elmer Moderator

    Something just dawned on me... Are you keying the rig from the key jack on the back of the radio or from a Maestro? Are you remote or local to your radio?

  • Pat_W5WTH
    Pat_W5WTH Member ✭✭

    If you are remote from a Maestro this, unfortunately, is the way it is. If you have everything plugged into the Flex directly I don’t think you should see that problem.

    My Maestro workaround (I think is ridiculous that I have to do) is to manually press the MOX button before I start sending CW and manually release it when done. I don’t do this all the time as the problem you mention only happens at initial key down. Once you “get going” the long delay you have set helps. During a ragchew I will typically do the manual MOX work around.

    You will kinda get used to it, but you shouldn’t have to. I wish Flex could correct it.

  • Pete Parisetti
    Pete Parisetti Member ✭✭
    edited March 2021

    Thanks both. Nope, no Maestro involved. No remote control. Key connected to the back of the 6400 and that's it.

    Unless there is a setting that somehow tells the system it is being remotely controlled?

    I will try the reset option.


  • MichaelCaditz
    MichaelCaditz Member, Unconfirmed
    Did this issue get resolved? I am considering purchasing a 6400. My main mode of operation will be CW.
  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin

    There are many ways you can configure the radio to work CW.

    The best performance is by using the Audio Systems and CW keying directly connected to the back of the radio. The CW sidetone is generated via the speaker/headset connections on the physical radio.


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