diff --git a/DXLabSuiteCommanderTransceiver.hpp b/DXLabSuiteCommanderTransceiver.hpp
index e23c32a58..c039857bc 100644
--- a/DXLabSuiteCommanderTransceiver.hpp
+++ b/DXLabSuiteCommanderTransceiver.hpp
@@ -33,7 +33,7 @@ public:
 protected:
   void do_start () override;
   void do_stop () override;
-  void do_frequency (Frequency, MODE = UNK) override;
+  void do_frequency (Frequency, MODE) override;
   void do_tx_frequency (Frequency, bool rationalise_mode) override;
   void do_mode (MODE, bool rationalise) override;
   void do_ptt (bool on) override;
diff --git a/HRDTransceiver.cpp b/HRDTransceiver.cpp
index 5b3d937bf..b0c3c1c09 100644
--- a/HRDTransceiver.cpp
+++ b/HRDTransceiver.cpp
@@ -13,6 +13,10 @@
 namespace
 {
   char const * const HRD_transceiver_name = "Ham Radio Deluxe";
+
+  // some commands require a settling time, particularly "RX A" and
+  // "RX B" on the Yaesu FTdx3000.
+  int constexpr yaesu_delay {250};
 }
 
 void HRDTransceiver::register_transceivers (TransceiverFactory::Transceivers * registry, int id)
@@ -445,6 +449,10 @@ void HRDTransceiver::set_button (int button_index, bool checked)
   if (button_index >= 0)
     {
       send_simple_command ("set button-select " + buttons_.value (button_index) + (checked ? " 1" : " 0"));
+      if (button_index == rx_A_button_ || button_index == rx_B_button_)
+        {
+          QThread::msleep (yaesu_delay);
+        }
     }
   else
     {
@@ -840,7 +848,7 @@ QString HRDTransceiver::send_command (QString const& cmd, bool no_debug, bool pr
       // required on some radios because commands don't get executed
       // correctly otherwise (ICOM for example)
       QThread::msleep (50);
-    }
+   }
 
   if (!recurse && prepend_context)
     {
diff --git a/HRDTransceiver.hpp b/HRDTransceiver.hpp
index 43341874a..87a9a439b 100644
--- a/HRDTransceiver.hpp
+++ b/HRDTransceiver.hpp
@@ -41,9 +41,9 @@ protected:
   // Implement the TransceiverBase interface.
   void do_start () override;
   void do_stop () override;
-  void do_frequency (Frequency, MODE = UNK) override;
-  void do_tx_frequency (Frequency, bool rationalise_mode = true) override;
-  void do_mode (MODE, bool rationalise = true) override;
+  void do_frequency (Frequency, MODE) override;
+  void do_tx_frequency (Frequency, bool rationalise_mode) override;
+  void do_mode (MODE, bool rationalise) override;
   void do_ptt (bool on) override;
 
   // Implement the PollingTransceiver interface.
diff --git a/HamlibTransceiver.hpp b/HamlibTransceiver.hpp
index 8e7f8d8fe..567ac3dbe 100644
--- a/HamlibTransceiver.hpp
+++ b/HamlibTransceiver.hpp
@@ -33,9 +33,9 @@ class HamlibTransceiver final
  private:
   void do_start () override;
   void do_stop () override;
-  void do_frequency (Frequency, MODE = UNK) override;
-  void do_tx_frequency (Frequency, bool rationalise_mode = true) override;
-  void do_mode (MODE, bool rationalise = true) override;
+  void do_frequency (Frequency, MODE) override;
+  void do_tx_frequency (Frequency, bool rationalise_mode) override;
+  void do_mode (MODE, bool rationalise) override;
   void do_ptt (bool) override;
 
   void poll () override;
diff --git a/OmniRigTransceiver.hpp b/OmniRigTransceiver.hpp
index 729543c8a..f2b4e3528 100644
--- a/OmniRigTransceiver.hpp
+++ b/OmniRigTransceiver.hpp
@@ -35,7 +35,7 @@ public:
 
   void do_start () override;
   void do_stop () override;
-  void do_frequency (Frequency, MODE = UNK) override;
+  void do_frequency (Frequency, MODE) override;
   void do_tx_frequency (Frequency, bool rationalise_mode) override;
   void do_mode (MODE, bool rationalise) override;
   void do_ptt (bool on) override;
diff --git a/TransceiverBase.hpp b/TransceiverBase.hpp
index 8430ad498..673736380 100644
--- a/TransceiverBase.hpp
+++ b/TransceiverBase.hpp
@@ -98,8 +98,8 @@ protected:
   virtual void do_frequency (Frequency rx, MODE = UNK) = 0;
   virtual void do_post_frequency (Frequency, MODE = UNK) {}
 
-  virtual void do_tx_frequency (Frequency tx = 0, bool rationalise_mode = true) = 0;
-  virtual void do_post_tx_frequency (Frequency, bool /* rationalise_mode */ = true) {}
+  virtual void do_tx_frequency (Frequency tx = 0u, bool rationalise_mode = false) = 0;
+  virtual void do_post_tx_frequency (Frequency = 0u, bool /* rationalise_mode */ = false) {}
 
   virtual void do_mode (MODE, bool rationalise = true) = 0;
   virtual void do_post_mode (MODE, bool /* rationalise */ = true) {}