Explicitly allow the Fox to transmit after the Tx frequency has been set at least 3 kHz from the main FT8 sub-bands.

widgets/mainwindow.cpp

@@ -4916,6 +4916,7 @@ void MainWindow::guiUpdate()
             MessageBox::warning_message (this, tr ("Fox Mode warning"), message);
           });
           break;
+          if(qAbs(kHzdiff) > 2999) m_bTxTime=true;  // allow Tx again
         }
       }
     }