Why am I hearing "DX" over and over on FT8?

Discussion in 'Working Different Modes' started by KB0NAV, Jan 7, 2018.

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  1. W6UV

    W6UV Premium Subscriber QRZ Page

    An Asus Xonar U5 has a dynamic range of 119 dB.
     
  2. SM0XHJ

    SM0XHJ Ham Member QRZ Page

    Sure, but whats the point when what you get from the rig is 90 dB at best.
    I have heard of issues where Windows thinks the rig (or the signalink in this case) is a microphone and applies a 30 dB amplification to the received signal. That would be experienced as a drop of 30 dB in dynamic range after adjusting down the volume to compensate. That might be what you have experienced.
    Whatever sound card is used, it's wise to NOT use the primary soundcard windows use for notification sounds for your rig...
     
  3. W6UV

    W6UV Premium Subscriber QRZ Page

    I know how to configure Windows for digital modes and did not have the 30 dB amp turned on. I did notice much more noise in the audio provided by the SignaLink to Fldigi and wsjt-x than I saw with a better sound card like the Xonar. It's easily visible on those program's waterfalls with the rig connected to a dummy load.
     
  4. SM0XHJ

    SM0XHJ Ham Member QRZ Page

  5. W4NNF

    W4NNF XML Subscriber QRZ Page

    If you don't have a rig with a built in soundcard, or an interface with a built in soundcard, you have to use the computer's internal soundcard same thing that JT Alert is using.
     
  6. W5KI

    W5KI Ham Member QRZ Page

    Noted this issue today ... and had heard it before. Unfortunately, my common sense was still taking a nap and I knew I had set something wrong in JTAlert. Up and down every line of the SETTINGS I went.

    Then I found this thread. Still no light bulb on. I knew that the "DX" was not going out over the air, but it was driving me crazy in the shack ... What had I done to the setup? Finally I re-read this thread a second time. Went back and tuned up freq slightly and listened, then down freq and listened. Announcement changed pitch. Yep, somebody over the air (not me) was causing it.

    Now for a little investigative work. But I'm fairly confident the operator(s) left the rig monitoring .313 and and aren't there to see the brief change to transmit.
     

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