diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3301b2c6b..18641b495 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -205,6 +205,8 @@ set (wsjt_qt_CXXSRCS
   NetworkMessage.cpp
   MessageClient.cpp
   LettersSpinBox.cpp
+  HintedSpinBox.cpp
+  RestrictedSpinBox.cpp
   HelpTextWindow.cpp
   SampleDownloader.cpp
   SampleDownloader/DirectoryDelegate.cpp
diff --git a/HintedSpinBox.cpp b/HintedSpinBox.cpp
new file mode 100644
index 000000000..25ffcc718
--- /dev/null
+++ b/HintedSpinBox.cpp
@@ -0,0 +1,55 @@
+#include "HintedSpinBox.hpp"
+
+#include <algorithm>
+
+auto HintedSpinBox::values (values_type values, bool set_min_max) -> values_type
+{
+  // replace any prior values
+  std::swap (values, values_);
+
+  // sort values and make unique
+  std::sort (values_.begin (), values_.end ());
+  auto last = std::unique (values_.begin (), values_.end ());
+  values_.erase (last, values_.end ());
+  if (set_min_max)
+    {
+      setMinimum (values_.front ());
+      setMaximum (values_.back ());
+    }
+  return values;                // return old values
+}
+
+void HintedSpinBox::stepBy (int steps)
+{
+  if (values_.size ())
+    {
+      if (steps > 0)
+        {
+          auto p = std::upper_bound (values_.begin (), values_.end (), value ());
+          if (p != values_.end () && *p <= maximum ())
+            {
+              setValue (*p);
+            }
+          else if (wrapping ())
+            {
+              setValue (values_.front ());
+            }
+        }
+      else if (steps < 0)
+        {
+          auto p = std::lower_bound (values_.begin (), values_.end (), value ());
+          if (p != values_.begin () && *(p - 1) >= minimum ())
+            {
+              setValue (*(p - 1));
+            }
+          else if (wrapping ())
+            {
+              setValue (values_.back ());
+            }
+        }
+    }
+  else
+    {
+      QSpinBox::stepBy (steps); // no values so revert to QSpinBox behaviour
+    }
+}
diff --git a/HintedSpinBox.hpp b/HintedSpinBox.hpp
new file mode 100644
index 000000000..beeb640c1
--- /dev/null
+++ b/HintedSpinBox.hpp
@@ -0,0 +1,53 @@
+#ifndef HINTED_SPIN_BOX_HPP_
+#define HINTED_SPIN_BOX_HPP_
+
+#include <vector>
+
+#include <QSpinBox>
+
+//
+// HintedSpinBox - QSpinBox refinement with an optional sequence of
+//                 discrete hints
+//
+//  The  hint  sequence  values  are  used  as  step  values  and  can
+//  optionally  define the  minimum and  maximum value.   Intermediate
+//  values are  allowed but  the step  up/down arrows  and accelerator
+//  keys will only use the hints.
+//
+//  Ensure that the default minimum  and maximum values are sufficient
+//  to allow initial initialization if done before the hints are set.
+//
+class HintedSpinBox
+  : public QSpinBox
+{
+public:
+  typedef std::vector<int> values_type;
+
+  HintedSpinBox (QWidget * parent = nullptr)
+    : QSpinBox {parent}
+  {
+  }
+
+  // Initialize sequence of values allowed.
+  //
+  // This  spin box  behaves exactly  as  a standard  QSpinBox if  the
+  // sequence of values is empty.
+  //
+  // The minimum and  maximum are automatically set to  the lowest and
+  // highest value provided if required.
+  //
+  // Returns the previous sequence.
+  values_type values (values_type values, bool set_min_max = true);
+
+  // Read access to the values.
+  values_type const& values () const {return values_;}
+
+protected:
+  // override the QSpinBox stepping
+  void stepBy (int steps) override;
+
+private:
+  std::vector<int> values_;
+};
+
+#endif
diff --git a/LettersSpinBox.cpp b/LettersSpinBox.cpp
index 0ee7462ec..9079d8d98 100644
--- a/LettersSpinBox.cpp
+++ b/LettersSpinBox.cpp
@@ -1,43 +1,25 @@
 #include "LettersSpinBox.hpp"
+
 #include <QString>
-#include <QDebug>
 #include "moc_LettersSpinBox.cpp"
 
 QString LettersSpinBox::textFromValue (int value) const
 {
   QString text;
-
-  if(value < 10) {
-    do {
-      auto digit = value % 26;
-      value /= 26;
-      text = QChar {lowercase_ ? 'a' + digit : 'A' + digit} + text;
-    } while (value);
-  } else {
-    if(value==11) text="5";
-    if(value==12) text="10";
-    if(value==13) text="15";
-    if(value==14) text="30";
-//    if(value==15) text="60";
-
-    if(value==21) text="10";
-    if(value==22) text="20";
-    if(value==23) text="50";
-    if(value==24) text="100";
-    if(value==25) text="200";
-    if(value==26) text="500";
-    if(value==27) text="1000";
-  }
+  do {
+    auto digit = value % 26;
+    value /= 26;
+    text = QChar {lowercase_ ? 'a' + digit : 'A' + digit} + text;
+  } while (value);
   return text;
 }
 
-/*
 int LettersSpinBox::valueFromText (QString const& text) const
 {
   int value {0};
-  for (int index = text.size (); index > 0; --index) {
-    value = value * 26 + text[index - 1].toLatin1 () - (lowercase_ ? 'a' : 'A');
-  }
+  for (int index = text.size (); index > 0; --index)
+    {
+      value = value * 26 + text[index - 1].toLatin1 () - (lowercase_ ? 'a' : 'A');
+    }
   return value;
 }
-*/
diff --git a/LettersSpinBox.hpp b/LettersSpinBox.hpp
index 0c73b27ec..aaa37d7fe 100644
--- a/LettersSpinBox.hpp
+++ b/LettersSpinBox.hpp
@@ -22,7 +22,7 @@ public:
   }
 
   QString textFromValue (int) const override;
-//  int valueFromText (QString const&) const override;
+  int valueFromText (QString const&) const override;
 
 private:
   bool lowercase_;
diff --git a/RestrictedSpinBox.cpp b/RestrictedSpinBox.cpp
new file mode 100644
index 000000000..d3201b331
--- /dev/null
+++ b/RestrictedSpinBox.cpp
@@ -0,0 +1,19 @@
+#include "RestrictedSpinBox.hpp"
+
+#include <algorithm>
+#include <utility>
+
+#include <QString>
+
+QValidator::State RestrictedSpinBox::validate (QString& input, int& pos) const
+{
+  // start by doing the standard QSpinBox validation
+  auto valid = HintedSpinBox::validate (input, pos);
+  // extra validation
+  if (QValidator::Acceptable
+      && values ().end () == std::find (values ().begin (), values ().end (), valueFromText (input)))
+    {
+      valid = QValidator::Intermediate;
+    }
+  return valid;
+}
diff --git a/RestrictedSpinBox.hpp b/RestrictedSpinBox.hpp
new file mode 100644
index 000000000..f856e90ce
--- /dev/null
+++ b/RestrictedSpinBox.hpp
@@ -0,0 +1,25 @@
+#ifndef RESTRICTED_SPIN_BOX_HPP_
+#define RESTRICTED_SPIN_BOX_HPP_
+
+#include "HintedSpinBox.hpp"
+
+class QString;
+
+//
+// RestrictedSpinBox - select only from a sequence of values
+//
+class RestrictedSpinBox final
+  : public HintedSpinBox
+{
+public:
+  RestrictedSpinBox (QWidget * parent = nullptr)
+    : HintedSpinBox {parent}
+  {
+  }
+
+protected:
+  // override the base class validation
+  QValidator::State validate (QString& input, int& pos) const override;
+};
+
+#endif
diff --git a/mainwindow.cpp b/mainwindow.cpp
index 04ecf6e04..bed494d5f 100644
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -230,7 +230,6 @@ MainWindow::MainWindow(QDir const& temp_directory, bool multiple,
   m_k0 {9999999},
   m_nPick {0},
   m_frequency_list_fcal_iter {m_config.frequencies ()->begin ()},
-  m_TRperiodFast {-1},
   m_nTx73 {0},
   m_btxok {false},
   m_diskData {false},
@@ -365,6 +364,7 @@ MainWindow::MainWindow(QDir const& temp_directory, bool multiple,
   add_child_to_event_filter (this);
   ui->dxGridEntry->setValidator (new MaidenheadLocatorValidator {this});
   ui->dxCallEntry->setValidator (new CallsignValidator {this});
+  ui->sbTR->values ({5, 10, 15, 30});
 
   m_baseCall = Radio::base_callsign (m_config.my_callsign ());
 
@@ -803,8 +803,6 @@ MainWindow::MainWindow(QDir const& temp_directory, bool multiple,
   on_actionWide_Waterfall_triggered();
   m_wideGraph->setTol(500);
   m_wideGraph->setLockTxFreq(m_lockTxFreq);
-  ui->sbFtol->setValue(m_FtolIndex);
-  on_sbFtol_valueChanged(m_FtolIndex);
   ui->cbShMsgs->setChecked(m_bShMsgs);
   ui->cbSWL->setChecked(m_bSWL);
   ui->cbFast9->setChecked(m_bFast9);
@@ -824,7 +822,6 @@ MainWindow::MainWindow(QDir const& temp_directory, bool multiple,
   if(m_mode=="FreqCal") on_actionFreqCal_triggered();
 
   ui->sbSubmode->setValue (vhf ? m_nSubMode : 0);
-  ui->sbTR->setValue(m_TRindex);
   if(m_mode=="MSK144") {
     Q_EMIT transmitFrequency (1000.0);
   } else {
@@ -862,14 +859,8 @@ MainWindow::MainWindow(QDir const& temp_directory, bool multiple,
   VHF_features_enabled(m_config.enable_VHF_features());
   m_wideGraph->setVHF(m_config.enable_VHF_features());
 
-  progressBar.setMaximum(m_TRperiod);
-  m_modulator->setPeriod(m_TRperiod); // TODO - not thread safe
   connect( wsprNet, SIGNAL(uploadStatus(QString)), this, SLOT(uploadResponse(QString)));
-  if(m_bFastMode) {
-    int ntr[]={5,10,15,30};
-    m_TRperiod=ntr[m_TRindex-11];
-    m_fastGraph->setTRperiod(m_TRperiod);
-  }
+
   statusChanged();
 
   m_fastGraph->setMode(m_mode);
@@ -964,10 +955,9 @@ void MainWindow::writeSettings()
   m_settings->setValue("RxFreq",ui->RxFreqSpinBox->value());
   m_settings->setValue("TxFreq",ui->TxFreqSpinBox->value());
   m_settings->setValue("WSPRfreq",ui->WSPRfreqSpinBox->value());
-  m_settings->setValue("TRindex",ui->sbTR->value());
   m_settings->setValue("SubMode",ui->sbSubmode->value());
   m_settings->setValue("DTtol",m_DTtol);
-  m_settings->setValue("FtolIndex",m_FtolIndex);
+  m_settings->setValue("Ftol", ui->sbFtol->value ());
   m_settings->setValue("MinSync",m_minSync);
   m_settings->setValue ("AutoSeq", ui->cbAutoSeq->isChecked ());
   m_settings->setValue("ShMsgs",m_bShMsgs);
@@ -984,7 +974,7 @@ void MainWindow::writeSettings()
   m_settings->setValue ("WSPRPreferType1", ui->WSPR_prefer_type_1_check_box->isChecked ());
   m_settings->setValue("UploadSpots",m_uploadSpots);
   m_settings->setValue ("BandHopping", ui->band_hopping_group_box->isChecked ());
-  m_settings->setValue("TRindex",m_TRindex);
+  m_settings->setValue ("TRPeriod", ui->sbTR->value ());
   m_settings->setValue("FastMode",m_bFastMode);
   m_settings->setValue("Fast9",m_bFast9);
   m_settings->setValue ("CQTxfreq", ui->sbCQTxFreq->value ());
@@ -1033,8 +1023,7 @@ void MainWindow::readSettings()
   ui->RxFreqSpinBox->setValue(0); // ensure a change is signaled
   ui->RxFreqSpinBox->setValue(m_settings->value("RxFreq",1500).toInt());
   m_nSubMode=m_settings->value("SubMode",0).toInt();
-  m_FtolIndex=m_settings->value("FtolIndex",21).toInt();
-//  ui->FTol_combo_box->setCurrentText(m_settings->value("FTol","500").toString ());
+  ui->sbFtol->setValue (m_settings->value("Ftol", 20).toInt());
   m_minSync=m_settings->value("MinSync",0).toInt();
   ui->syncSpinBox->setValue(m_minSync);
   ui->cbAutoSeq->setChecked (m_settings->value ("AutoSeq", false).toBool());
@@ -1042,9 +1031,9 @@ void MainWindow::readSettings()
   m_bSWL=m_settings->value("SWL",false).toBool();
   m_bFast9=m_settings->value("Fast9",false).toBool();
   m_bFastMode=m_settings->value("FastMode",false).toBool();
-  m_TRindex=m_settings->value("TRindex",0).toInt();
+  ui->sbTR->setValue (m_settings->value ("TRPeriod", 30).toInt());
   m_lastMonitoredFrequency = m_settings->value ("DialFreq",
-     QVariant::fromValue<Frequency> (default_frequency)).value<Frequency> ();
+    QVariant::fromValue<Frequency> (default_frequency)).value<Frequency> ();
   ui->WSPRfreqSpinBox->setValue(0); // ensure a change is signaled
   ui->WSPRfreqSpinBox->setValue(m_settings->value("WSPRfreq",1500).toInt());
   ui->TxFreqSpinBox->setValue(0); // ensure a change is signaled
@@ -1067,7 +1056,6 @@ void MainWindow::readSettings()
   ui->tabWidget->setCurrentIndex(n);
   outBufSize=m_settings->value("OutBufSize",4096).toInt();
   m_lockTxFreq=m_settings->value("LockTxFreq",false).toBool();
-  m_TRindex=m_settings->value("TRindex",4).toInt();
   m_pwrBandTxMemory=m_settings->value("pwrBandTxMemory").toHash();
   m_pwrBandTuneMemory=m_settings->value("pwrBandTuneMemory").toHash();
   {
@@ -1182,7 +1170,8 @@ void MainWindow::dataSink(qint64 frames)
       && !(m_ihsym % 8) && m_ihsym > 8 && m_ihsym <= m_hsymStop) {
     int RxFreq=ui->RxFreqSpinBox->value ();
     int nkhz=(m_freqNominal+RxFreq)/1000;
-    freqcal_(&dec_data.d2[0],&k,&nkhz,&RxFreq,&m_Ftol,&line[0],80);
+    int ftol = ui->sbFtol->value ();
+    freqcal_(&dec_data.d2[0],&k,&nkhz,&RxFreq,&ftol,&line[0],80);
     QString t=QString::fromLatin1(line);
     DecodedText decodedtext;
     decodedtext=t;
@@ -1397,7 +1386,8 @@ void MainWindow::fastSink(qint64 frames)
   strncpy(ddir,dataDir.toLatin1(), sizeof (ddir) - 1);
   float pxmax = 0;
   float rmsNoGain = 0;
-  hspec_(dec_data.d2,&k,&nutc0,&nTRpDepth,&RxFreq,&m_Ftol,&bmsk144,&bcontest,
+  int ftol = ui->sbFtol->value ();
+  hspec_(dec_data.d2,&k,&nutc0,&nTRpDepth,&RxFreq,&ftol,&bmsk144,&bcontest,
          &m_bTrain,m_phaseEqCoefficients.constData(),&m_inGain,&dec_data.params.mycall[0],
          &dec_data.params.hiscall[0],&bshmsg,&bswl,
          &ddir[0],fast_green,fast_s,&fast_jh,&pxmax,&rmsNoGain,&line[0],&dec_data.params.mygrid[0],
@@ -2389,7 +2379,7 @@ void MainWindow::decode()                                       //decode()
   dec_data.params.nfa=m_wideGraph->nStartFreq();
   dec_data.params.nfSplit=m_wideGraph->Fmin();
   dec_data.params.nfb=m_wideGraph->Fmax();
-  dec_data.params.ntol=m_Ftol;
+  dec_data.params.ntol=ui->sbFtol->value ();
   if(m_mode=="JT9+JT65" or !m_config.enable_VHF_features()) {
     dec_data.params.ntol=20;
     dec_data.params.naggressive=0;
@@ -2472,7 +2462,7 @@ void MainWindow::decode()                                       //decode()
     if(m_mode=="JT9") narg[9]=102;            //Fast JT9
     if(m_mode=="MSK144") narg[9]=104;         //MSK144
     narg[10]=ui->RxFreqSpinBox->value();
-    narg[11]=m_Ftol;
+    narg[11]=ui->sbFtol->value ();
     narg[12]=0;
     narg[13]=-1;
     narg[14]=m_config.aggressive();
@@ -4328,7 +4318,7 @@ void MainWindow::on_actionJT9_triggered()
   ui->sbSubmode->setMaximum(7);
   fast_config(m_bFastMode);
   if(m_bFast9) {
-    m_TRperiod=ui->sbTR->cleanText().toInt();
+    m_TRperiod = ui->sbTR->value ();
     m_wideGraph->hide();
     m_fastGraph->show();
     ui->TxFreqSpinBox->setValue(700);
@@ -4472,7 +4462,7 @@ void MainWindow::on_actionISCAT_triggered()
   displayWidgets(nWidgets("100111000000000110000000"));
   m_modeTx="ISCAT";
   ui->actionISCAT->setChecked(true);
-  m_TRperiod=ui->sbTR->cleanText().toInt();
+  m_TRperiod = ui->sbTR->value ();
   m_modulator->setPeriod(m_TRperiod);
   m_detector->setPeriod(m_TRperiod);
   m_wideGraph->setPeriod(m_TRperiod,m_nsps);
@@ -4520,9 +4510,7 @@ void MainWindow::on_actionMSK144_triggered()
   m_bFastMode=true;
   m_bFast9=false;
   fast_config(true);
-  if(m_TRperiodFast<=15) ui->sbTR->setValue(m_TRperiodFast/5+10);
-  if(m_TRperiodFast==30) ui->sbTR->setValue(14);
-  m_TRperiod=ui->sbTR->cleanText().toInt();
+  m_TRperiod = ui->sbTR->value ();
   m_wideGraph->hide();
   m_fastGraph->show();
   ui->TxFreqSpinBox->setValue(1500);
@@ -4542,8 +4530,7 @@ void MainWindow::on_actionMSK144_triggered()
   ui->rptSpinBox->setMaximum(24);
   ui->rptSpinBox->setValue(0);
   ui->rptSpinBox->setSingleStep(1);
-  ui->sbFtol->setMinimum(22);
-  ui->sbFtol->setMaximum(25);
+  ui->sbFtol->values ({20, 50, 100, 200});
   statusChanged();
 }
 
@@ -4634,8 +4621,7 @@ void MainWindow::on_actionFreqCal_triggered()
   switch_mode(Modes::FreqCal);
   m_wideGraph->setMode(m_mode);
   statusChanged();
-  ui->sbTR->setValue(14);
-  m_TRperiod=ui->sbTR->cleanText().toInt();
+  m_TRperiod = ui->sbTR->value ();
   m_modulator->setPeriod(m_TRperiod); // TODO - not thread safe
   m_detector->setPeriod(m_TRperiod);  // TODO - not thread safe
   m_nsps=6912;                        //For symspec only
@@ -4661,8 +4647,7 @@ void MainWindow::switch_mode (Mode mode)
   ui->rptSpinBox->setSingleStep(1);
   ui->rptSpinBox->setMinimum(-50);
   ui->rptSpinBox->setMaximum(49);
-  ui->sbFtol->setMinimum(21);
-  ui->sbFtol->setMaximum(27);
+  ui->sbFtol->values ({10, 20, 50, 100, 200, 500, 1000});
   if(m_mode=="MSK144") {
     ui->RxFreqSpinBox->setMinimum(1400);
     ui->RxFreqSpinBox->setMaximum(1600);
@@ -4718,7 +4703,6 @@ void MainWindow::fast_config(bool b)
   ui->TxFreqSpinBox->setEnabled(!b);
   ui->sbTR->setVisible(b);
   if(b and (m_bFast9 or m_mode=="MSK144" or m_mode=="ISCAT")) {
-    ui->sbTR->setValue(m_TRindex);
     m_wideGraph->hide();
     m_fastGraph->show();
   } else {
@@ -5564,12 +5548,9 @@ void MainWindow::transmitDisplay (bool transmitting)
   }
 }
 
-void MainWindow::on_sbFtol_valueChanged(int index)
+void MainWindow::on_sbFtol_valueChanged(int value)
 {
-  int tol[] = {10,20,50,100,200,500,1000};
-  m_FtolIndex=index;
-  m_Ftol=tol[index-21];
-  m_wideGraph->setTol(m_Ftol);
+  m_wideGraph->setTol (value);
 }
 
 void::MainWindow::VHF_features_enabled(bool b)
@@ -5588,16 +5569,16 @@ void::MainWindow::VHF_features_enabled(bool b)
   }
 }
 
-void MainWindow::on_sbTR_valueChanged(int index)
+void MainWindow::on_sbTR_valueChanged(int value)
 {
-  m_TRindex=index;
 //  if(!m_bFastMode and n>m_nSubMode) m_MinW=m_nSubMode;
   if(m_bFastMode or m_mode=="FreqCal") {
-    m_TRperiod=ui->sbTR->cleanText().toInt();
-    if(m_TRperiod<5 or m_TRperiod>30) m_TRperiod=15;
-    m_TRindex=ui->sbTR->value();
-    m_TRperiodFast=m_TRperiod;
-    progressBar.setMaximum(m_TRperiod);
+    m_TRperiod = value;
+    m_fastGraph->setTRperiod (value);
+    m_modulator->setPeriod (value); // TODO - not thread safe
+    m_detector->setPeriod (value);  // TODO - not thread safe
+    m_wideGraph->setPeriod (value, m_nsps);
+    progressBar.setMaximum (value);
   }
   if(m_monitoring) {
     on_stopButton_clicked();
@@ -5606,10 +5587,6 @@ void MainWindow::on_sbTR_valueChanged(int index)
   if(m_transmitting) {
     on_stopTxButton_clicked();
   }
-  m_modulator->setPeriod(m_TRperiod); // TODO - not thread safe
-  m_detector->setPeriod(m_TRperiod);  // TODO - not thread safe
-  m_wideGraph->setPeriod(m_TRperiod,m_nsps);
-  m_fastGraph->setTRperiod(m_TRperiod);
 }
 
 QChar MainWindow::current_submode () const
@@ -5666,7 +5643,7 @@ void MainWindow::on_cbFast9_clicked(bool b)
   }
 
   if(b) {
-    if(m_TRperiodFast>0) m_TRperiod=m_TRperiodFast;
+    m_TRperiod = ui->sbTR->value ();
   } else {
     m_TRperiod=60;
   }
diff --git a/mainwindow.h b/mainwindow.h
index b5c4dc2d0..a732aa9c6 100644
--- a/mainwindow.h
+++ b/mainwindow.h
@@ -255,8 +255,8 @@ private slots:
   void on_actionMeasure_reference_spectrum_triggered();
   void on_actionErase_reference_spectrum_triggered();
   void on_actionMeasure_phase_response_triggered();
-  void on_sbTR_valueChanged(int index);
-  void on_sbFtol_valueChanged(int index);
+  void on_sbTR_valueChanged (int);
+  void on_sbFtol_valueChanged (int);
   void on_cbFast9_clicked(bool b);
   void on_sbCQTxFreq_valueChanged(int n);
   void on_cbCQTx_toggled(bool b);
@@ -381,11 +381,7 @@ private:
   qint32  m_k0;
   qint32  m_kdone;
   qint32  m_nPick;
-  qint32  m_TRindex;
-  qint32  m_FtolIndex;
-  qint32  m_Ftol;
   FrequencyList::const_iterator m_frequency_list_fcal_iter;
-  qint32  m_TRperiodFast;
   qint32  m_nTx73;
   qint32  m_UTCdisk;
   qint32  m_wait;
diff --git a/mainwindow.ui b/mainwindow.ui
index 25e1b3cb4..d1385cc31 100644
--- a/mainwindow.ui
+++ b/mainwindow.ui
@@ -562,7 +562,7 @@ QLabel[oob=&quot;true&quot;] {
         <item row="0" column="3" rowspan="3">
          <widget class="QStackedWidget" name="controls_stack_widget">
           <property name="currentIndex">
-           <number>1</number>
+           <number>0</number>
           </property>
           <widget class="QWidget" name="page">
            <layout class="QHBoxLayout" name="horizontalLayout_8">
@@ -615,13 +615,7 @@ QLabel[oob=&quot;true&quot;] {
                   </widget>
                  </item>
                  <item row="5" column="0">
-                  <widget class="LettersSpinBox" name="sbFtol">
-                   <property name="maximumSize">
-                    <size>
-                     <width>120</width>
-                     <height>16777215</height>
-                    </size>
-                   </property>
+                  <widget class="HintedSpinBox" name="sbFtol">
                    <property name="toolTip">
                     <string>Frequency tolerance (Hz)</string>
                    </property>
@@ -632,15 +626,18 @@ QLabel[oob=&quot;true&quot;] {
                     <string>F Tol  </string>
                    </property>
                    <property name="minimum">
-                    <number>21</number>
+                    <number>10</number>
                    </property>
                    <property name="maximum">
-                    <number>27</number>
+                    <number>1000</number>
+                   </property>
+                   <property name="value">
+                    <number>10</number>
                    </property>
                   </widget>
                  </item>
                  <item row="9" column="0">
-                  <widget class="LettersSpinBox" name="sbTR">
+                  <widget class="RestrictedSpinBox" name="sbTR">
                    <property name="toolTip">
                     <string>&lt;html&gt;&lt;head/&gt;&lt;body&gt;&lt;p&gt;Tx/Rx or Frequency calibration sequence length&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;</string>
                    </property>
@@ -654,13 +651,13 @@ QLabel[oob=&quot;true&quot;] {
                     <string>T/R  </string>
                    </property>
                    <property name="minimum">
-                    <number>11</number>
+                    <number>5</number>
                    </property>
                    <property name="maximum">
-                    <number>14</number>
+                    <number>30</number>
                    </property>
                    <property name="value">
-                    <number>14</number>
+                    <number>30</number>
                    </property>
                   </widget>
                  </item>
@@ -3011,6 +3008,16 @@ QPushButton[state=&quot;ok&quot;] {
    <header>signalmeter.h</header>
    <container>1</container>
   </customwidget>
+  <customwidget>
+   <class>HintedSpinBox</class>
+   <extends>QSpinBox</extends>
+   <header>HintedSpinBox.hpp</header>
+  </customwidget>
+  <customwidget>
+   <class>RestrictedSpinBox</class>
+   <extends>QSpinBox</extends>
+   <header>RestrictedSpinBox.hpp</header>
+  </customwidget>
  </customwidgets>
  <tabstops>
   <tabstop>logQSOButton</tabstop>