diff --git a/devices/limesdr/devicelimesdr.cpp b/devices/limesdr/devicelimesdr.cpp
index c091dbc7b..4e10cab52 100644
--- a/devices/limesdr/devicelimesdr.cpp
+++ b/devices/limesdr/devicelimesdr.cpp
@@ -50,7 +50,7 @@ bool DeviceLimeSDR::setNCOFrequency(lms_device_t *device, bool dir_tx, std::size
             return false;
         }
 
-        if (LMS_SetNCOIndex(device, dir_tx, chan, 0, !positive) < 0)
+        if (LMS_SetNCOIndex(device, dir_tx, chan, 0, positive) < 0)
         {
             fprintf(stderr, "DeviceLimeSDR::setNCOFrequency: cannot set conversion direction %sfreq\n", positive ? "+" : "-");
             return false;
diff --git a/plugins/samplesource/limesdrinput/limesdrinputgui.cpp b/plugins/samplesource/limesdrinput/limesdrinputgui.cpp
index b440ab69b..d8385b32b 100644
--- a/plugins/samplesource/limesdrinput/limesdrinputgui.cpp
+++ b/plugins/samplesource/limesdrinput/limesdrinputgui.cpp
@@ -298,7 +298,7 @@ void LimeSDRInputGUI::displaySettings()
     ui->extClock->setExternalClockFrequency(m_settings.m_extClockFreq);
     ui->extClock->setExternalClockActive(m_settings.m_extClock);
 
-    ui->centerFrequency->setValue(m_settings.m_centerFrequency / 1000);
+    setCenterFrequencyDisplay();
     ui->sampleRate->setValue(m_settings.m_devSampleRate);
 
     ui->dcOffset->setChecked(m_settings.m_dcBlock);
@@ -347,11 +347,41 @@ void LimeSDRInputGUI::displaySettings()
 void LimeSDRInputGUI::setNCODisplay()
 {
     int ncoHalfRange = (m_settings.m_devSampleRate * (1<<(m_settings.m_log2HardDecim)))/2;
-    int lowBoundary = std::max(0, (int) m_settings.m_centerFrequency - ncoHalfRange);
-    ui->ncoFrequency->setValueRange(7,
-            lowBoundary/1000,
-            (m_settings.m_centerFrequency + ncoHalfRange)/1000); // frequency dial is in kHz
-    ui->ncoFrequency->setValue((m_settings.m_centerFrequency + m_settings.m_ncoFrequency)/1000);
+    ui->ncoFrequency->setValueRange(
+            false,
+            8,
+            -ncoHalfRange,
+            ncoHalfRange); // frequency dial is in kHz
+
+    ui->ncoFrequency->blockSignals(true);
+    ui->ncoFrequency->setValue(m_settings.m_ncoFrequency);
+    ui->ncoFrequency->blockSignals(false);
+}
+
+void LimeSDRInputGUI::setCenterFrequencyDisplay()
+{
+    int64_t centerFrequency = m_settings.m_centerFrequency;
+    ui->centerFrequency->setToolTip(QString("Main center frequency in kHz (LO: %1 kHz)").arg(centerFrequency/1000));
+
+    if (m_settings.m_ncoEnable) {
+        centerFrequency += m_settings.m_ncoFrequency;
+    }
+
+    ui->centerFrequency->blockSignals(true);
+    ui->centerFrequency->setValue(centerFrequency < 0 ? 0 : (uint64_t) centerFrequency/1000); // kHz
+    ui->centerFrequency->blockSignals(false);
+}
+
+void LimeSDRInputGUI::setCenterFrequencySetting(uint64_t kHzValue)
+{
+    int64_t centerFrequency = kHzValue*1000;
+
+    if (m_settings.m_ncoEnable) {
+        centerFrequency -= m_settings.m_ncoFrequency;
+    }
+
+    m_settings.m_centerFrequency = centerFrequency < 0 ? 0 : (uint64_t) centerFrequency;
+    ui->centerFrequency->setToolTip(QString("Main center frequency in kHz (LO: %1 kHz)").arg(centerFrequency/1000));
 }
 
 void LimeSDRInputGUI::sendSettings()
@@ -455,28 +485,28 @@ void LimeSDRInputGUI::on_record_toggled(bool checked)
 
 void LimeSDRInputGUI::on_centerFrequency_changed(quint64 value)
 {
-    m_settings.m_centerFrequency = value * 1000;
-    setNCODisplay();
+    setCenterFrequencySetting(value);
     sendSettings();
 }
 
-void LimeSDRInputGUI::on_ncoFrequency_changed(quint64 value)
+void LimeSDRInputGUI::on_ncoFrequency_changed(qint64 value)
 {
-    m_settings.m_ncoFrequency = (int64_t) value - (int64_t) m_settings.m_centerFrequency/1000;
-    m_settings.m_ncoFrequency *= 1000;
+    m_settings.m_ncoFrequency = value;
+    setCenterFrequencyDisplay();
     sendSettings();
 }
 
 void LimeSDRInputGUI::on_ncoEnable_toggled(bool checked)
 {
     m_settings.m_ncoEnable = checked;
+    setCenterFrequencyDisplay();
     sendSettings();
 }
 
 void LimeSDRInputGUI::on_ncoReset_clicked(bool checked __attribute__((unused)))
 {
     m_settings.m_ncoFrequency = 0;
-    ui->ncoFrequency->setValue(m_settings.m_centerFrequency/1000);
+    ui->ncoFrequency->setValue(0);
     sendSettings();
 }
 
diff --git a/plugins/samplesource/limesdrinput/limesdrinputgui.h b/plugins/samplesource/limesdrinput/limesdrinputgui.h
index 2bc328dfe..b8966d5ba 100644
--- a/plugins/samplesource/limesdrinput/limesdrinputgui.h
+++ b/plugins/samplesource/limesdrinput/limesdrinputgui.h
@@ -69,6 +69,8 @@ private:
 
     void displaySettings();
     void setNCODisplay();
+    void setCenterFrequencyDisplay();
+    void setCenterFrequencySetting(uint64_t kHzValue);
     void sendSettings();
     void updateSampleRateAndFrequency();
     void updateADCRate();
@@ -79,7 +81,7 @@ private slots:
     void on_startStop_toggled(bool checked);
     void on_record_toggled(bool checked);
     void on_centerFrequency_changed(quint64 value);
-    void on_ncoFrequency_changed(quint64 value);
+    void on_ncoFrequency_changed(qint64 value);
     void on_ncoEnable_toggled(bool checked);
     void on_ncoReset_clicked(bool checked);
     void on_dcOffset_toggled(bool checked);
diff --git a/plugins/samplesource/limesdrinput/limesdrinputgui.ui b/plugins/samplesource/limesdrinput/limesdrinputgui.ui
index 80c5b34ef..8abb76250 100644
--- a/plugins/samplesource/limesdrinput/limesdrinputgui.ui
+++ b/plugins/samplesource/limesdrinput/limesdrinputgui.ui
@@ -35,16 +35,7 @@
    <property name="spacing">
     <number>3</number>
    </property>
-   <property name="leftMargin">
-    <number>2</number>
-   </property>
-   <property name="topMargin">
-    <number>2</number>
-   </property>
-   <property name="rightMargin">
-    <number>2</number>
-   </property>
-   <property name="bottomMargin">
+   <property name="margin">
     <number>2</number>
    </property>
    <item>
@@ -256,7 +247,7 @@
       </widget>
      </item>
      <item>
-      <widget class="ValueDial" name="ncoFrequency" native="true">
+      <widget class="ValueDialZ" name="ncoFrequency" native="true">
        <property name="sizePolicy">
         <sizepolicy hsizetype="Maximum" vsizetype="Maximum">
          <horstretch>0</horstretch>
@@ -281,14 +272,14 @@
         <cursorShape>PointingHandCursor</cursorShape>
        </property>
        <property name="toolTip">
-        <string>Center frequency with NCO engaged (kHz)</string>
+        <string>NCO frequency (Hz)</string>
        </property>
       </widget>
      </item>
      <item>
       <widget class="QLabel" name="ncoUnits">
        <property name="text">
-        <string>kHz</string>
+        <string>Hz</string>
        </property>
       </widget>
      </item>
@@ -1166,6 +1157,12 @@ QToolTip{background-color: white; color: black;}</string>
    <extends>QToolButton</extends>
    <header>gui/externalclockbutton.h</header>
   </customwidget>
+  <customwidget>
+   <class>ValueDialZ</class>
+   <extends>QWidget</extends>
+   <header>gui/valuedialz.h</header>
+   <container>1</container>
+  </customwidget>
  </customwidgets>
  <resources>
   <include location="../../../sdrgui/resources/res.qrc"/>