diff --git a/NANOVNA_STM32_F303/adc.c b/NANOVNA_STM32_F303/adc.c
index 20610e6..5e60cf4 100644
--- a/NANOVNA_STM32_F303/adc.c
+++ b/NANOVNA_STM32_F303/adc.c
@@ -21,7 +21,7 @@
 #include "hal.h"
 #include "nanovna.h"
 
-#define ADC_FULL_SCALE  3000
+#define ADC_FULL_SCALE  3300
 #define F303_ADC_VREF_ALWAYS_ON
 
 #define ADC_CHSELR_VREFINT      ADC_CHANNEL_IN18
diff --git a/main.c b/main.c
index af405b4..cd79494 100644
--- a/main.c
+++ b/main.c
@@ -154,7 +154,7 @@ static THD_FUNCTION(Thread1, arg)
       b.mode = setting.mode;
       uint32_t *f = (uint32_t *)&b;
       uint32_t *t = &backup;
-      int i = 5;
+      int i = USED_BACKUP_SIZE;
       while (i--)
         *t++ = *f++;
 
@@ -2576,7 +2576,7 @@ int main(void)
 #endif
   if(config_recall()) {
     uint32_t *f = &backup;     // Clear backup when no valid config data
-    int i = 5;
+    int i = USED_BACKUP_SIZE;
     while (i--)
       *f++ = 0;
   }
@@ -2632,10 +2632,10 @@ int main(void)
     backup_t b;
     uint32_t *f = &backup;
     uint32_t *t = (uint32_t *)&b;
-    int i = 5;
+    int i = USED_BACKUP_SIZE;
     while (i--)
       *t++ = *f++;
-#if 0       // Set mode not working reliably
+#ifdef TINYSA4       // Set mode not working reliably
     set_mode(b.mode);
     switch (b.mode) {
     case M_LOW:
diff --git a/nanovna.h b/nanovna.h
index 7f7178b..342d3c0 100644
--- a/nanovna.h
+++ b/nanovna.h
@@ -1564,7 +1564,7 @@ extern const menuitem_t  menu_mode[];
 extern void menu_push_submenu(const menuitem_t *submenu);
 
 typedef struct {
-  uint32_t    frequency0, frequency1;
+  freq_t    frequency0, frequency1;
   uint8_t attenuation;
   uint8_t reflevel;
   uint8_t RBW;
@@ -1574,7 +1574,17 @@ typedef struct {
 
 #define backup (*(uint32_t *)0x40002850)   // backup registers 5 * 32 bits
 
+#ifdef TINYSA4
+#define MAX_BACKUP_SIZE 16
+#define USED_BACKUP_SIZE 5
+#else
+#define MAX_BACKUP_SIZE 5
+#define USED_BACKUP_SIZE 3
+#endif
 
+#if USED_BACKUP_SIZE > MAX_BACKUP_SIZE
+#error "backup_t too large"
+#endif
 /*
  * misclinous
  */