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Can't turn QSK off

Hi folks,

Using a 6400 (without internal tuner) here with SSDR 3.1.12. While operating CW during the recent RAC Winter contest, I found that I could not turn off QSK. I tried restarting SSDR and the radio and neither had any impact. It also does not matter if N1MM+ is running or not. Any suggestions?

Pierre VE3KTB

Best Answer

  • Tim - W4TME
    Tim - W4TME Administrator, FlexRadio Employee admin
    Answer ✓

    The radio has to be in several different antenna configurations for the radio (the hardware) to be capable of QSK operation. The QSK indicator communicates this hardware capability, not that you are actually operating in QSK mode. Whether or not you are operating in QSK mode is dependent on the CW delay setting.

    How to operate in QSK mode is covered in the SmartSDR Software User Guide, section 23.2 CW Transmitting.


  • KD0RC
    KD0RC Member, Super Elmer Moderator

    Hi Pierre, Did you try changing the CW Delay?


    Len, KD0RC

  • No, I haven't. I have only clicked the Breakin button, and it does change colour. What value should I set the delay to?
  • And I should add that the qsk indicator in the flag does not change.
  • KD0RC
    KD0RC Member, Super Elmer Moderator

    I only get the QSK indicator to change if I turn TX on or off. For 24 WPM, a delay of 200 seems about right. To try it out without transmitting, turn your RF Power to 0, turn Breakin on, and make sure TX is on. Now you can get a feel for how much delay based on your WPM by watching the panadapter. If it jumps between elements, characters or words, you need more delay. If it holds the receiver quiet for too long, you need less.



  • KD0RC
    KD0RC Member, Super Elmer Moderator

    OK, I did find a QSK button at the top of the CWX setup screen. Apparently, it only affects CWX messages and anything you type into the CWX screen. The Delay control affects CWX and the paddles.



  • Lionel
    Lionel Member ✭✭✭

    I use QSK most of the time. Delay at 0, filter set to low latency position.

    Someone gave me a tip to turn on FDX and this made a noticeable difference but I don't know why.

    This keeps me a happy QSK op at 25wpm or so. I've never used CWX.

    I am always RX/TX on Ant 1, usually not split, though QSK works just fine.

    Rarely I increase the delay and effectively exit QSK.

  • Tim, thanks for the explanation on how it works. I had read that section, but I misunderstood the statement "The BREAKIN control allows automatic PTT when the key is pressed" inferring it meant that turning BREAKIN off would mean no qsk.

    I did some tests with the delay setting and determined that at 24 wpm I had no breakin from 40 ms up. I decided on a delay of 50 ms to give some leeway.

    This was all generated because my Heathkit HL2200 has very loud clunking relays that literally caused me to jump when I transitioned from SSB to CW during the RAC contest.

    Thanks to all for your input!


    Pierre VE3KTB

  • Chris WX7V
    Chris WX7V Member ✭✭
    edited August 2021

    It took me a minute to understand QSK as well - I couldn't reduce the Delay to 0 on my 6400 because I had the ATU enabled on 20M and only 1 antenna for TX/RX.

    Increasing the delay value will allow levels QSK between letters or words while sending.

    The current version of the manual says in section 23.2 CW Transmitting:

    QSK is not available for single antenna ATU operation. If the ATU is required during QSK operation, a separate receive antenna port (such as RX-A, RX-B, XVTR-A or XVTR-B) must be employed.

    Also note that in section 29.5 Antenna Options clarifies that the receive antenna cannot be ANT1 or ANT2:

    QSK is not supported with a separate receive antenna if that antenna is connected to ANT1 or ANT2.

    More information in Section 29.13 clarifies:

    PIN diode silent CW QSK operation on ANT1 and ANT2 require that both receive and transmit be on the same antenna or that a dedicated receive-only antenna be used (ideal for QSK) on RX A, RX B, or XVTR. If ANT1 and ANT2 are used separately as receive and transmit antennas, the transmitter reverts to mechanical relay TR switching.


    Chris de WX7V

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