diff --git a/devices/bladerf2/devicebladerf2shared.cpp b/devices/bladerf2/devicebladerf2shared.cpp
index d33c1a3da..7339a7021 100644
--- a/devices/bladerf2/devicebladerf2shared.cpp
+++ b/devices/bladerf2/devicebladerf2shared.cpp
@@ -18,6 +18,10 @@
 
 MESSAGE_CLASS_DEFINITION(DeviceBladeRF2Shared::MsgReportBuddyChange, Message)
 
+const float  DeviceBladeRF2Shared::m_sampleFifoLengthInSeconds = 0.25;
+const int    DeviceBladeRF2Shared::m_sampleFifoMinSize = 75000; // 300 kS/s knee
+const int    DeviceBladeRF2Shared::m_sampleFifoMinSize32 = 150000; // Fixed for interpolation by 32
+
 DeviceBladeRF2Shared::DeviceBladeRF2Shared() :
     m_dev(0),
     m_channel(-1),
diff --git a/devices/bladerf2/devicebladerf2shared.h b/devices/bladerf2/devicebladerf2shared.h
index fbb2c9c55..43474d7fa 100644
--- a/devices/bladerf2/devicebladerf2shared.h
+++ b/devices/bladerf2/devicebladerf2shared.h
@@ -79,6 +79,10 @@ public:
     int m_channel; //!< allocated channel (-1 if none)
     BladeRF2Input *m_source;
     BladeRF2Output *m_sink;
+
+    static const float m_sampleFifoLengthInSeconds;
+    static const int   m_sampleFifoMinSize;
+    static const int   m_sampleFifoMinSize32;
 };
 
 
diff --git a/plugins/samplesink/bladerf2output/bladerf2output.cpp b/plugins/samplesink/bladerf2output/bladerf2output.cpp
index fe1d38575..87a3f2331 100644
--- a/plugins/samplesink/bladerf2output/bladerf2output.cpp
+++ b/plugins/samplesink/bladerf2output/bladerf2output.cpp
@@ -645,6 +645,37 @@ bool BladeRF2Output::applySettings(const BladeRF2OutputSettings& settings, bool
     struct bladerf *dev = m_deviceShared.m_dev->getDev();
     int requestedChannel = m_deviceAPI->getItemIndex();
 
+    if ((m_settings.m_devSampleRate != settings.m_devSampleRate) || (m_settings.m_log2Interp != settings.m_log2Interp) || force)
+    {
+        BladeRF2OutputThread *bladeRF2OutputThread = findThread();
+        SampleSourceFifo *fifo = 0;
+
+        if (bladeRF2OutputThread)
+        {
+            fifo = bladeRF2OutputThread->getFifo(requestedChannel);
+            bladeRF2OutputThread->setFifo(requestedChannel, 0);
+        }
+
+        int fifoSize;
+
+        if (settings.m_log2Interp >= 5)
+        {
+            fifoSize = DeviceBladeRF2Shared::m_sampleFifoMinSize32;
+        }
+        else
+        {
+            fifoSize = std::max(
+                (int) ((settings.m_devSampleRate/(1<<settings.m_log2Interp)) * DeviceBladeRF2Shared::m_sampleFifoLengthInSeconds),
+                DeviceBladeRF2Shared::m_sampleFifoMinSize);
+        }
+
+        m_sampleSourceFifo.resize(fifoSize);
+
+        if (fifo) {
+            bladeRF2OutputThread->setFifo(requestedChannel, &m_sampleSourceFifo);
+        }
+    }
+
     if ((m_settings.m_devSampleRate != settings.m_devSampleRate) || force)
     {
         forwardChangeOwnDSP = true;
@@ -663,7 +694,7 @@ bool BladeRF2Output::applySettings(const BladeRF2OutputSettings& settings, bool
             }
             else
             {
-                qDebug() << "BladeRF2Output::applySettings: bladerf_set_sample_rate(BLADERF_MODULE_RX) actual sample rate is " << actualSamplerate;
+                qDebug() << "BladeRF2Output::applySettings: bladerf_set_sample_rate: actual sample rate is " << actualSamplerate;
             }
         }
     }
@@ -684,7 +715,7 @@ bool BladeRF2Output::applySettings(const BladeRF2OutputSettings& settings, bool
             }
             else
             {
-                qDebug() << "BladeRF2Output::applySettings: bladerf_set_bandwidth(BLADERF_MODULE_RX) actual bandwidth is " << actualBandwidth;
+                qDebug() << "BladeRF2Output::applySettings: bladerf_set_bandwidth: actual bandwidth is " << actualBandwidth;
             }
         }
     }
@@ -736,25 +767,7 @@ bool BladeRF2Output::applySettings(const BladeRF2OutputSettings& settings, bool
         m_deviceShared.m_dev->setBiasTeeTx(settings.m_biasTee);
     }
 
-    if ((m_settings.m_gainMode != settings.m_gainMode) || force)
-    {
-        forwardChangeTxBuddies = true;
-
-        if (dev)
-        {
-            int status = bladerf_set_gain_mode(dev, BLADERF_CHANNEL_TX(requestedChannel), (bladerf_gain_mode) settings.m_gainMode);
-
-            if (status < 0) {
-                qWarning("BladeRF2Output::applySettings: bladerf_set_gain_mode(%d) failed: %s",
-                        settings.m_gainMode, bladerf_strerror(status));
-            } else {
-                qDebug("BladeRF2Output::applySettings: bladerf_set_gain_mode(%d)", settings.m_gainMode);
-            }
-        }
-    }
-
-    if ((m_settings.m_globalGain != settings.m_globalGain)
-       || ((m_settings.m_gainMode != settings.m_gainMode) && (settings.m_gainMode == BLADERF_GAIN_MANUAL)) || force)
+    if ((m_settings.m_globalGain != settings.m_globalGain) || force)
     {
         forwardChangeTxBuddies = true;
 
@@ -821,7 +834,6 @@ bool BladeRF2Output::applySettings(const BladeRF2OutputSettings& settings, bool
             << " m_log2Interp: " << m_settings.m_log2Interp
             << " m_devSampleRate: " << m_settings.m_devSampleRate
             << " m_globalGain: " << m_settings.m_globalGain
-            << " m_gainMode: " << m_settings.m_gainMode
             << " m_biasTee: " << m_settings.m_biasTee;
 
     return true;
@@ -860,9 +872,6 @@ int BladeRF2Output::webapiSettingsPutPatch(
     if (deviceSettingsKeys.contains("biasTee")) {
         settings.m_biasTee = response.getBladeRf2OutputSettings()->getBiasTee() != 0;
     }
-    if (deviceSettingsKeys.contains("gainMode")) {
-        settings.m_gainMode = response.getBladeRf2OutputSettings()->getGainMode();
-    }
     if (deviceSettingsKeys.contains("globalGain")) {
         settings.m_globalGain = response.getBladeRf2OutputSettings()->getGlobalGain();
     }
@@ -895,7 +904,6 @@ void BladeRF2Output::webapiFormatDeviceSettings(SWGSDRangel::SWGDeviceSettings&
     response.getBladeRf2OutputSettings()->setBandwidth(settings.m_bandwidth);
     response.getBladeRf2OutputSettings()->setLog2Interp(settings.m_log2Interp);
     response.getBladeRf2OutputSettings()->setBiasTee(settings.m_biasTee ? 1 : 0);
-    response.getBladeRf2OutputSettings()->setGainMode(settings.m_gainMode);
     response.getBladeRf2OutputSettings()->setGlobalGain(settings.m_globalGain);
 }
 
diff --git a/plugins/samplesink/bladerf2output/bladerf2outputsettings.cpp b/plugins/samplesink/bladerf2output/bladerf2outputsettings.cpp
index 2a69e969b..b7f808c01 100644
--- a/plugins/samplesink/bladerf2output/bladerf2outputsettings.cpp
+++ b/plugins/samplesink/bladerf2output/bladerf2outputsettings.cpp
@@ -30,8 +30,7 @@ void BladeRF2OutputSettings::resetToDefaults()
     m_centerFrequency = 435000*1000;
     m_devSampleRate = 3072000;
     m_bandwidth = 1500000;
-    m_gainMode = 0;
-    m_globalGain = -20;
+    m_globalGain = -3;
     m_biasTee = false;
     m_log2Interp = 0;
 }
@@ -42,7 +41,6 @@ QByteArray BladeRF2OutputSettings::serialize() const
 
     s.writeS32(1, m_devSampleRate);
     s.writeS32(2, m_bandwidth);
-    s.writeS32(3, m_gainMode);
     s.writeS32(4, m_globalGain);
     s.writeBool(5, m_biasTee);
     s.writeU32(6, m_log2Interp);
@@ -64,7 +62,6 @@ bool BladeRF2OutputSettings::deserialize(const QByteArray& data)
     {
         d.readS32(1, &m_devSampleRate);
         d.readS32(2, &m_bandwidth);
-        d.readS32(3, &m_gainMode);
         d.readS32(4, &m_globalGain);
         d.readBool(5, &m_biasTee);
         d.readU32(6, &m_log2Interp);
diff --git a/plugins/samplesink/bladerf2output/bladerf2outputsettings.h b/plugins/samplesink/bladerf2output/bladerf2outputsettings.h
index 29132165a..333aa750d 100644
--- a/plugins/samplesink/bladerf2output/bladerf2outputsettings.h
+++ b/plugins/samplesink/bladerf2output/bladerf2outputsettings.h
@@ -24,7 +24,6 @@ struct BladeRF2OutputSettings {
     quint64 m_centerFrequency;
     qint32 m_devSampleRate;
     qint32 m_bandwidth;
-    int m_gainMode;
     int m_globalGain;
     bool m_biasTee;
     quint32 m_log2Interp;
diff --git a/plugins/samplesink/bladerf2output/bladerf2outputthread.cpp b/plugins/samplesink/bladerf2output/bladerf2outputthread.cpp
index 87fd1cfdd..f02ab126b 100644
--- a/plugins/samplesink/bladerf2output/bladerf2outputthread.cpp
+++ b/plugins/samplesink/bladerf2output/bladerf2outputthread.cpp
@@ -92,10 +92,10 @@ void BladeRF2OutputThread::run()
                 if (m_nbChannels > 1) {
                     callbackMO(m_buf, DeviceBladeRF2::blockSize);
                 } else {
-                    callbackSO(m_buf, 2*DeviceBladeRF2::blockSize);
+                    callbackSO(m_buf, DeviceBladeRF2::blockSize);
                 }
 
-                res = bladerf_sync_tx(m_dev, m_buf, DeviceBladeRF2::blockSize, NULL, 10000);
+                res = bladerf_sync_tx(m_dev, m_buf, DeviceBladeRF2::blockSize, 0, 10000);
 
                 if (res < 0)
                 {
@@ -166,7 +166,7 @@ void BladeRF2OutputThread::callbackMO(qint16* buf, qint32 samplesPerChannel)
     for (unsigned int channel = 0; channel < m_nbChannels; channel++)
     {
         if (m_channels[channel].m_sampleFifo) {
-            callbackSO(&buf[2*samplesPerChannel*channel], 2*samplesPerChannel, channel);
+            callbackSO(&buf[2*samplesPerChannel*channel], samplesPerChannel, channel);
         } else {
             std::fill(&buf[2*samplesPerChannel*channel], &buf[2*samplesPerChannel*channel]+2*samplesPerChannel, 0); // fill with zero samples
         }
@@ -182,42 +182,57 @@ void BladeRF2OutputThread::callbackMO(qint16* buf, qint32 samplesPerChannel)
     }
 }
 
-//  Interpolate according to specified log2 (ex: log2=4 => decim=16)
+//  Interpolate according to specified log2 (ex: log2=4 => decim=16). len is a number of samples (not a number of I or Q)
 void BladeRF2OutputThread::callbackSO(qint16* buf, qint32 len, unsigned int channel)
 {
-    SampleVector::iterator beginRead;
-    m_channels[channel].m_sampleFifo->readAdvance(beginRead, len/(1<<m_channels[channel].m_log2Interp));
-    beginRead -= len;
-
-    if (m_channels[channel].m_log2Interp == 0)
+    if (m_channels[channel].m_sampleFifo)
     {
-        m_channels[channel].m_interpolators.interpolate1(&beginRead, buf, len*2);
+        float bal = m_channels[channel].m_sampleFifo->getRWBalance();
+
+        if (bal < -0.25) {
+            qDebug("BladeRF2OutputThread::callbackSO: read lags: %f", bal);
+        } else if (bal > 0.25) {
+            qDebug("BladeRF2OutputThread::callbackSO: read leads: %f", bal);
+        }
+
+        SampleVector::iterator beginRead;
+        m_channels[channel].m_sampleFifo->readAdvance(beginRead, len/(1<<m_channels[channel].m_log2Interp));
+        beginRead -= len;
+
+        if (m_channels[channel].m_log2Interp == 0)
+        {
+            m_channels[channel].m_interpolators.interpolate1(&beginRead, buf, len*2);
+        }
+        else
+        {
+            switch (m_channels[channel].m_log2Interp)
+            {
+            case 1:
+                m_channels[channel].m_interpolators.interpolate2_cen(&beginRead, buf, len*2);
+                break;
+            case 2:
+                m_channels[channel].m_interpolators.interpolate4_cen(&beginRead, buf, len*2);
+                break;
+            case 3:
+                m_channels[channel].m_interpolators.interpolate8_cen(&beginRead, buf, len*2);
+                break;
+            case 4:
+                m_channels[channel].m_interpolators.interpolate16_cen(&beginRead, buf, len*2);
+                break;
+            case 5:
+                m_channels[channel].m_interpolators.interpolate32_cen(&beginRead, buf, len*2);
+                break;
+            case 6:
+                m_channels[channel].m_interpolators.interpolate64_cen(&beginRead, buf, len*2);
+                break;
+            default:
+                break;
+            }
+        }
     }
     else
     {
-        switch (m_channels[channel].m_log2Interp)
-        {
-        case 1:
-            m_channels[channel].m_interpolators.interpolate2_cen(&beginRead, buf, len*2);
-            break;
-        case 2:
-            m_channels[channel].m_interpolators.interpolate4_cen(&beginRead, buf, len*2);
-            break;
-        case 3:
-            m_channels[channel].m_interpolators.interpolate8_cen(&beginRead, buf, len*2);
-            break;
-        case 4:
-            m_channels[channel].m_interpolators.interpolate16_cen(&beginRead, buf, len*2);
-            break;
-        case 5:
-            m_channels[channel].m_interpolators.interpolate32_cen(&beginRead, buf, len*2);
-            break;
-        case 6:
-            m_channels[channel].m_interpolators.interpolate64_cen(&beginRead, buf, len*2);
-            break;
-        default:
-            break;
-        }
+        std::fill(buf, buf+2*len, 0);
     }
 }
 
diff --git a/plugins/samplesource/bladerf2input/bladerf2input.cpp b/plugins/samplesource/bladerf2input/bladerf2input.cpp
index 0eba5ae8b..6060311b1 100644
--- a/plugins/samplesource/bladerf2input/bladerf2input.cpp
+++ b/plugins/samplesource/bladerf2input/bladerf2input.cpp
@@ -735,7 +735,7 @@ bool BladeRF2Input::applySettings(const BladeRF2InputSettings& settings, bool fo
             }
             else
             {
-                qDebug() << "BladeRF2Input::applySettings: bladerf_set_sample_rate(BLADERF_MODULE_RX) actual sample rate is " << actualSamplerate;
+                qDebug() << "BladeRF2Input::applySettings: bladerf_set_sample_rate: actual sample rate is " << actualSamplerate;
             }
         }
     }
@@ -756,7 +756,7 @@ bool BladeRF2Input::applySettings(const BladeRF2InputSettings& settings, bool fo
             }
             else
             {
-                qDebug() << "BladeRF2Input::applySettings: bladerf_set_bandwidth(BLADERF_MODULE_RX) actual bandwidth is " << actualBandwidth;
+                qDebug() << "BladeRF2Input::applySettings: bladerf_set_bandwidth: actual bandwidth is " << actualBandwidth;
             }
         }
     }
diff --git a/sdrbase/dsp/samplesourcefifo.h b/sdrbase/dsp/samplesourcefifo.h
index 1374e3d57..5d33eba14 100644
--- a/sdrbase/dsp/samplesourcefifo.h
+++ b/sdrbase/dsp/samplesourcefifo.h
@@ -43,7 +43,7 @@ public:
 
     void write(const Sample& sample);                        //!< write directly - phase 1 + phase 2
 
-    /** returns ratio of off center over buffer size with sign: negative real lags and positive read leads */
+    /** returns ratio of off center over buffer size with sign: negative read lags and positive read leads */
     float getRWBalance() const
     {
         int delta;
diff --git a/swagger/sdrangel/api/swagger/include/BladeRF2.yaml b/swagger/sdrangel/api/swagger/include/BladeRF2.yaml
index 3d5c16dc2..d8816fa23 100644
--- a/swagger/sdrangel/api/swagger/include/BladeRF2.yaml
+++ b/swagger/sdrangel/api/swagger/include/BladeRF2.yaml
@@ -51,8 +51,6 @@ BladeRF2OutputSettings:
       type: integer
     bandwidth:
       type: integer
-    gainMode:
-      type: integer
     globalGain:
       type: integer
     biasTee: