diff --git a/nanovna.h b/nanovna.h
index 98cb1aa..b9734e5 100644
--- a/nanovna.h
+++ b/nanovna.h
@@ -456,7 +456,7 @@ void clear_frequency_cache(void);
 void toggle_high_out_adf4350(void);
 extern int high_out_adf4350;
 #endif
-void set_30mhz(freq_t);
+int set_actual_freq(int);
 void set_IF2(int f);
 void set_R(int f);
 extern void set_modulo(uint32_t f);
diff --git a/sa_cmd.c b/sa_cmd.c
index 03aab2b..ffaff9c 100644
--- a/sa_cmd.c
+++ b/sa_cmd.c
@@ -591,7 +591,7 @@ VNA_SHELL_FUNCTION(cmd_actual_freq)
     shell_printf("%DHz\r\n", config.setting_frequency_30mhz);
     return;
   } else {
-    set_30mhz(my_atoui(argv[0]));
+    set_actual_freq(my_atoui(argv[0]));
   }
 }
 #endif
diff --git a/sa_core.c b/sa_core.c
index 9af22d4..9330d10 100644
--- a/sa_core.c
+++ b/sa_core.c
@@ -803,15 +803,19 @@ void set_gridlines(int d)
 }
 
 #ifdef TINYSA4
-void set_30mhz(freq_t f)
+
+int set_actual_freq(int f)
 {
-//  if (f < 29000000 || f > 31000000)
-//    return;
-  config.setting_frequency_30mhz = f;
+  if (get_sweep_frequency(ST_CENTER) > 1000000000)
+    return -1;
+  if (f < - 10000 || f > +10000)
+    return -1;
+  config.setting_frequency_30mhz = 3000000000 + f * 3 ;
   ADF4351_recalculate_PFDRFout();
   config_save();
   dirty = true;
   update_grid();
+  return 0;
 }
 #else
 void set_10mhz(freq_t f)
@@ -7325,7 +7329,7 @@ void calibrate(void)
     set_auto_reflevel(true);
     setting.repeat = 10;
     //setting.scale = 1;
-    if (i == 5) {
+    if (i == 5) {                       // Not used !!!!!
       set_sweep_points(51);
       set_sweep_frequency(ST_SPAN,    50);
       setting.rbw_x10 = 3;
diff --git a/si4468.c b/si4468.c
index ea885b1..b0cc862 100644
--- a/si4468.c
+++ b/si4468.c
@@ -444,6 +444,7 @@ void ADF4351_R_counter(int R)
 void ADF4351_recalculate_PFDRFout(void){
   int local_r = old_R;
   old_R = -1;
+  local_setting_frequency_30mhz_x100 = config.setting_frequency_30mhz;
   ADF4351_R_counter(local_r);
 }
 
@@ -458,7 +459,7 @@ void ADF4350_shift_ref(int f) {
   if (f == shifted)
     return;
   shifted = false;
-  local_setting_frequency_30mhz_x100 = 3000000000;
+  local_setting_frequency_30mhz_x100 = config.setting_frequency_30mhz;
   if (shifted) {
     local_setting_frequency_30mhz_x100 = (local_setting_frequency_30mhz_x100 * SHIFT_MUL) / SHIFT_DIV;
   }
diff --git a/ui_sa.c b/ui_sa.c
index f5156c8..64e74f0 100644
--- a/ui_sa.c
+++ b/ui_sa.c
@@ -404,7 +404,7 @@ enum {
   // #10
   KM_SAMPLETIME, KM_LOWOUTLEVEL, KM_DECAY, KM_NOISE,
 #ifdef TINYSA4
-  KM_30MHZ, 
+  KM_FREQ_CORR,
 #else
   KM_10MHZ, 
 #endif
@@ -469,7 +469,7 @@ static const struct {
 [KM_DECAY]        = {keypads_positive    , "DECAY"},    // KM_DECAY
 [KM_NOISE]        = {keypads_positive    , "NOISE\nLEVEL"},    // KM_NOISE
 #ifdef TINYSA4
-[KM_30MHZ]        = {keypads_freq        , "FREQ"},    // KM_30MHz
+[KM_FREQ_CORR]    = {keypads_plusmin     , "PPB"},    // KM_FREQ_CORR
 #else
 [KM_10MHZ]        = {keypads_freq        , "FREQ"},    // KM_10MHz
 #endif
@@ -2971,7 +2971,7 @@ static const menuitem_t menu_settings2[] =
   { MT_KEYPAD,   KM_ATTACK,      "ATTACK\n\b%s",   "0..100000ms"},
 #endif
 #ifdef TINYSA4
-  { MT_KEYPAD,   KM_30MHZ,      "30MHz*100\n\b%s", "Enter actual 30MHz * 100"},
+  { MT_KEYPAD,   KM_FREQ_CORR,    "FREQ CORR\n\b%s", "Enter ppb correction"},
 #endif
   { MT_SUBMENU,  0,             S_RARROW" MORE",     menu_settings3},
   { MT_NONE,     0, NULL, menu_back} // next-> menu_back
@@ -3501,9 +3501,13 @@ static void fetch_numeric_target(uint8_t mode)
     plot_printf(uistat.text, sizeof uistat.text, "%d", ((int32_t)uistat.value));
     break;
 #ifdef TINYSA4
-  case KM_30MHZ:
-    uistat.freq_value = config.setting_frequency_30mhz;
-    plot_printf(uistat.text, sizeof uistat.text, "%.5QHz", uistat.freq_value);
+  case KM_FREQ_CORR:
+    if (config.setting_frequency_30mhz >= 3000000000ULL)
+      uistat.value = (config.setting_frequency_30mhz - 3000000000ULL)/3;
+    else
+      uistat.value = - ((int)(3000000000ULL - config.setting_frequency_30mhz))/3;
+
+    plot_printf(uistat.text, sizeof uistat.text, "%d", (int32_t)uistat.value);
     break;
 #else
   case KM_10MHZ:
@@ -3711,8 +3715,8 @@ set_numeric_value(void)
     set_noise(uistat.value);
     break;
 #ifdef TINYSA4
-  case KM_30MHZ:
-    set_30mhz(uistat.freq_value);
+  case KM_FREQ_CORR:
+    set_actual_freq(uistat.value);
     break;
 #else
   case KM_10MHZ: