diff --git a/libm65/map65a.f90 b/libm65/map65a.f90
index ab3a677e6..a9164b26d 100644
--- a/libm65/map65a.f90
+++ b/libm65/map65a.f90
@@ -270,10 +270,16 @@ subroutine map65a(dd,ss,savg,newdat,nutc,fcenter,ntol,idphi,nfa,nfb,        &
               f0=mhz+0.001*nkHz
               ndf=nint(1000.0*(freq-foffset-(nkHz+nfshift)))
               nsync1=sync1
-              nsync2=nint(10.0*log10(sync2)) - 40 !### empirical ###
-              if(nfast.eq.2) nsync2=nsync2 + 7
+
+              s2db=10.0*log10(sync2) - 40             !### empirical ###
+              nsync2=nint(s2db)
+              if(nfast.eq.2) nsync2=nint(s2db + 6.5)
               if(decoded(1:4).eq.'RO  ' .or. decoded(1:4).eq.'RRR  ' .or.  &
-                   decoded(1:4).eq.'73  ') nsync2=nsync2-6
+                   decoded(1:4).eq.'73  ') then
+                 if(nfast.eq.1) nsync2=nint(1.33*s2db + 2.0)
+                 if(nfast.eq.2) nsync2=nint(1.33*s2db + 2.7)
+              endif
+
               nwrite=nwrite+1
               if(nxant.ne.0) then
                  npol=npol-45
@@ -393,10 +399,16 @@ subroutine map65a(dd,ss,savg,newdat,nutc,fcenter,ntol,idphi,nfa,nfb,        &
            ndf1=nint(a(2))
            ndf2=nint(a(3))
            nsync1=sync1
-           nsync2=nint(10.0*log10(sync2)) - 40 !### empirical ###
-           if(nfast.eq.2) nsync2=nsync2 + 7
+
+           s2db=10.0*log10(sync2) - 40             !### empirical ###
+           nsync2=nint(s2db)
+           if(nfast.eq.2) nsync2=nint(s2db + 6.5)
            if(decoded(1:4).eq.'RO  ' .or. decoded(1:4).eq.'RRR  ' .or.  &
-                decoded(1:4).eq.'73  ') nsync2=nsync2-6
+                decoded(1:4).eq.'73  ') then
+              if(nfast.eq.1) nsync2=nint(1.33*s2db + 2.0)
+              if(nfast.eq.2) nsync2=nint(1.33*s2db + 2.7)
+           endif
+
            if(nxant.ne.0) then
               npol=npol-45
               if(npol.lt.0) npol=npol+180
diff --git a/mainwindow.cpp b/mainwindow.cpp
index da48c07d1..64fd995c4 100644
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -1627,8 +1627,12 @@ void MainWindow::doubleClickOnCall(QString hiscall, bool ctrl)
   QString t1 = t.mid(0,i2);              //contents up to text cursor
   int i1=t1.lastIndexOf("\n") + 1;
   QString t2 = t1.mid(i1,i2-i1);         //selected line
-  int n = 60*t2.mid(13,2).toInt() + t2.mid(15,2).toInt();
-  m_txFirst = ((n%2) == 1);
+  if(m_nfast==1) {
+    int n = 60*t2.mid(13,2).toInt() + t2.mid(15,2).toInt();
+    m_txFirst = ((n%2) == 1);
+  } else {
+    m_txFirst = (t2.mid(17,2).toInt()==30);
+  }
   ui->txFirstCheckBox->setChecked(m_txFirst);
   QString rpt="";
   if(ctrl) rpt=t2.mid(23,3);
@@ -1649,8 +1653,12 @@ void MainWindow::doubleClickOnMessages(QString hiscall, QString t2)
     msgBox("Possible dupe: " + hiscall + " already in log.");
   }
   ui->dxCallEntry->setText(hiscall);
-  int n = 60*t2.mid(13,2).toInt() + t2.mid(15,2).toInt();
-  m_txFirst = ((n%2) == 1);
+  if(m_nfast==1) {
+    int n = 60*t2.mid(13,2).toInt() + t2.mid(15,2).toInt();
+    m_txFirst = ((n%2) == 1);
+  } else {
+    m_txFirst = (t2.mid(17,2).toInt()==30);
+  }
   ui->txFirstCheckBox->setChecked(m_txFirst);
   lookup();
   genStdMsgs("");