According to the WSJT-X manual in section "5. Transceiver Setup" AGC should be turned off:
"Use the receiver gain controls and/or the computer¡¯s audio mixer controls to set the background noise level (scale at lower left of main window) to around 30 dB when no signals are present. It is usually best to turn AGC off or reduce the RF gain control to minimize AGC action."
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73, DB2OO - Joerg
