in this manual. The fault could also arise if the output volume is zero, which could be due to the
audio output channel being muted somewhere in your PC audio settings.
2 flashes:
QDX is receiving audio from your PC. But the volume is insufficient to trigger the key-down
(transmit) action. Remember that there is a “Rise Threshold” setting in the QDX Configuration
terminal application, which defaults to 80% of maximum value. If the amplitude of the audio
sinewave coming from the PC is less than 80%, key-down will never be triggered.
It is therefore highly recommended to set the audio output level of the PC to 100%. Unfortunately
this simple recommendation can be the cause of great confusion. The exact places to set the
volume varies also depending on the operating system (Windows, Linux, Mac). But in principle
there are THREE places on the PC that all affect the output channel volume, and all three need to
be set to 100%:
1. The output volume of the software application itself, for example the “Pwr” slider in the
bottom right area of the WSJT-X screen; these should always be left at maximum.
2. The output device corresponding to QDX must be set at 100% also. In Linux Sound
Manager (XUbuntu 18.04 example shown), the Output Devices tab for QDX should have its
slider set to 100% as per the example below. Don’t set it to more than 100%!
3. The “Master Volume” control of the PC should also be set to 100%. There is such a setting
in both Windows and Linux (and most likely Mac too). In Linux, clicking the loudspeaker
icon at the bottom right of the screen shows which audio device is being used for the
default sound output; selecting QDX will show you the master volume level, and it needs to
be set to 100% (not more, not less). There’s a similar thing on Windows OS.
QDX operating manual; firmware 1_04
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