diff --git a/USER_MANUAL.html b/USER_MANUAL.html
index ecf1623d7..b21c289a5 100644
--- a/USER_MANUAL.html
+++ b/USER_MANUAL.html
@@ -621,6 +621,7 @@ <h2 data-number="17.1" id="v1.8.12-tbd-2023"><span class="header-section-number"
 <li>Display ‘Digital’ on button when Analog mode is active. (PR #447)</li>
 <li>Set minimum size for Mode box to 250px. (PR #446)</li>
 <li>Notify FreeDV Reporter if only capable of RX. (PR #449)</li>
+<li>Hamlib: allow frequency and mode changes during TX. (PR #455)</li>
 </ul></li>
 <li>Build system:
 <ul>
diff --git a/USER_MANUAL.md b/USER_MANUAL.md
index 2b1dfa731..a0275f9ca 100644
--- a/USER_MANUAL.md
+++ b/USER_MANUAL.md
@@ -879,6 +879,7 @@ LDPC | Low Density Parity Check Codes - a family of powerful FEC codes
     * Display 'Digital' on button when Analog mode is active. (PR #447)
     * Set minimum size for Mode box to 250px. (PR #446)
     * Notify FreeDV Reporter if only capable of RX. (PR #449)
+    * Hamlib: allow frequency and mode changes during TX. (PR #455)
 3. Build system:
     * Bump Codec2 version to v1.1.1. (PR #437)
 4. Miscallenous:
diff --git a/USER_MANUAL.pdf b/USER_MANUAL.pdf
index 3628919ca..3f3acddd3 100644
Binary files a/USER_MANUAL.pdf and b/USER_MANUAL.pdf differ
diff --git a/src/hamlib.cpp b/src/hamlib.cpp
index dbd08921b..87de8d0bb 100644
--- a/src/hamlib.cpp
+++ b/src/hamlib.cpp
@@ -329,12 +329,86 @@ void Hamlib::disable_mode_detection()
 
 void Hamlib::setMode(bool analog, uint64_t frequencyHz)
 {
-    if (m_rig == nullptr || pttSet_ || readOnly_)
+    if (m_rig == nullptr || readOnly_)
+    {
+        // Ignore if not connected 
+        return;
+    }
+
+    if (pttSet_)
+    {
+        // If transmitting, temporarily stop transmitting so we can change the mode.
+        int result = rig_set_ptt(m_rig, RIG_VFO_CURR, RIG_PTT_OFF);
+        if (result != RIG_OK) 
+        {
+            // If we can't stop transmitting, we shouldn't try to change the mode
+            // as it'll fail on some radios.
+            if (g_verbose) fprintf(stderr, "rig_set_ptt: error = %s \n", rigerror(result));
+
+            return;
+        }
+    }
+
+    
+    vfo_t currVfo = getCurrentVfo_(); 
+    rmode_t mode = getHamlibMode_(analog, frequencyHz);
+    setModeHelper_(currVfo, mode);
+
+    if (pttSet_)
+    {
+        // If transmitting, temporarily stop transmitting so we can change the mode.
+        int result = rig_set_ptt(m_rig, RIG_VFO_CURR, RIG_PTT_ON);
+        if (result != RIG_OK) 
+        {
+            // If we can't stop transmitting, we shouldn't try to change the mode
+            // as it'll fail on some radios.
+            if (g_verbose) fprintf(stderr, "rig_set_ptt: error = %s \n", rigerror(result));
+        }
+    }
+}
+
+void Hamlib::setFrequencyAndMode(uint64_t frequencyHz, bool analog)
+{
+    if (m_rig == nullptr || readOnly_)
     {
         // Ignore if not connected or if transmitting
         return;
     }
     
+    if (pttSet_)
+    {
+        // If transmitting, temporarily stop transmitting so we can change the mode.
+        int result = rig_set_ptt(m_rig, RIG_VFO_CURR, RIG_PTT_OFF);
+        if (result != RIG_OK) 
+        {
+            // If we can't stop transmitting, we shouldn't try to change the mode
+            // as it'll fail on some radios.
+            if (g_verbose) fprintf(stderr, "rig_set_ptt: error = %s \n", rigerror(result));
+
+            return;
+        }
+    }
+
+    vfo_t currVfo = getCurrentVfo_(); 
+    rmode_t mode = getHamlibMode_(analog, frequencyHz);
+    setModeHelper_(currVfo, mode);
+    setFrequencyHelper_(currVfo, frequencyHz);
+
+    if (pttSet_)
+    {
+        // If transmitting, temporarily stop transmitting so we can change the mode.
+        int result = rig_set_ptt(m_rig, RIG_VFO_CURR, RIG_PTT_ON);
+        if (result != RIG_OK) 
+        {
+            // If we can't stop transmitting, we shouldn't try to change the mode
+            // as it'll fail on some radios.
+            if (g_verbose) fprintf(stderr, "rig_set_ptt: error = %s \n", rigerror(result));
+        }
+    }
+}
+  
+rmode_t Hamlib::getHamlibMode_(bool analog, uint64_t frequencyHz)
+{
     // Widest 60 meter allocation is 5.250-5.450 MHz per https://en.wikipedia.org/wiki/60-meter_band.
     bool is60MeterBand = frequencyHz >= 5250000 && frequencyHz <= 5450000;
     
@@ -361,24 +435,10 @@ void Hamlib::setMode(bool analog, uint64_t frequencyHz)
     {
         assert(0);
     }
-    
-    vfo_t currVfo = getCurrentVfo_(); 
-    setModeHelper_(currVfo, mode);
-}
 
-void Hamlib::setFrequencyAndMode(uint64_t frequencyHz, bool analog)
-{
-    if (m_rig == nullptr || pttSet_ || readOnly_)
-    {
-        // Ignore if not connected or if transmitting
-        return;
-    }
-    
-    vfo_t currVfo = getCurrentVfo_(); 
-    setMode(analog, frequencyHz);
-    setFrequencyHelper_(currVfo, frequencyHz);
+    return mode;
 }
-  
+
 void Hamlib::setModeHelper_(vfo_t currVfo, rmode_t mode)
 {
     bool setOkay = false;
@@ -596,6 +656,13 @@ void Hamlib::update_mode_status()
 
 void Hamlib::close(void) {
     if(m_rig) {
+        // Stop transmitting.
+        if (pttSet_)
+        {
+            wxString tmp;
+            ptt(false, tmp);
+        }
+
         // Turn off status thread if needed.
         disable_mode_detection();
        
diff --git a/src/hamlib.h b/src/hamlib.h
index ea78c0539..f53342b82 100644
--- a/src/hamlib.h
+++ b/src/hamlib.h
@@ -50,6 +50,7 @@ class Hamlib {
         typedef std::vector<const struct rig_caps *> riglist_t;
 
     private:
+        rmode_t getHamlibMode_(bool analog, uint64_t frequencyHz);
         void update_mode_status();
         void statusUpdateThreadEntryFn_();
         void update_from_hamlib_();