diff --git a/flash.c b/flash.c
index e5caf7b..6d11baf 100644
--- a/flash.c
+++ b/flash.c
@@ -233,6 +233,9 @@ caldata_recall(uint16_t id)
 
   /* duplicated saved data onto sram to be able to modify marker/trace */
   memcpy(dst, src, sizeof(setting_t));
+#ifdef __SD_FILE_BROWSER__
+  sd_preset_path[0] = 0;              // this preset came from flash, not from SD
+#endif
 #if 0
   // Restore stored trace
   src = &(src[1]);
diff --git a/main.c b/main.c
index 36f9d43..a7b085a 100644
--- a/main.c
+++ b/main.c
@@ -1986,10 +1986,10 @@ show_one:
     do_one = true;
     goto show_one;
   }
-#if MAX_UNIT_TYPE != 7
+#if MAX_UNIT_TYPE != 8
 #error "Unit type enum possibly changed, check cmd_trace function"
 #endif
-  static const char cmd_type_list[] = "dBm|dBmV|dBuV|RAW|V|Vpp|W";
+  static const char cmd_type_list[] = "dBm|dBmV|dBuV|RAW|V|Vpp|W|dBV";
   if (argc == 1) {
     int type = get_str_index(argv[0], cmd_type_list);
     if (type >= 0) {
diff --git a/nanovna.h b/nanovna.h
index 1068946..f323edd 100644
--- a/nanovna.h
+++ b/nanovna.h
@@ -775,13 +775,15 @@ enum trace_type {
 // Electrical Delay
 // Phase
 
-#define MAX_UNIT_TYPE 7     // Index of U_DBC
+#define MAX_UNIT_TYPE 8     // Index of U_DBC
+// New units must be appended before U_DBC, the values below U_DBC are stored in
+// setting.unit (flash presets and .prs files) and may not be renumbered
 enum unit_type {
-  U_DBM=0, U_DBMV, U_DBUV, U_RAW, U_VOLT, U_VPP, U_WATT, U_DBC //  dBc only for displaying delta marker info
+  U_DBM=0, U_DBMV, U_DBUV, U_RAW, U_VOLT, U_VPP, U_WATT, U_DBV, U_DBC //  dBc only for displaying delta marker info
 };
 
-#define UNIT_IS_LINEAR(T) ( T >= U_VOLT ? true : false)
-#define UNIT_IS_LOG(T) ( T >= U_VOLT ? false : true)
+#define UNIT_IS_LINEAR(T) ((T) >= U_VOLT && (T) <= U_WATT)
+#define UNIT_IS_LOG(T)   (!UNIT_IS_LINEAR(T))
 
 float value(float);
 float index_to_value(const int i);
@@ -1759,6 +1761,11 @@ void testLog(void);        // debug log
 void sd_card_load_config(char *filename);
 extern systime_t last_auto_save;
 void save_csv(uint8_t mask);
+#ifdef __SD_FILE_BROWSER__
+// Full path of the preset last loaded from SD, empty when the active preset did
+// not come from SD. Used to default the name when storing a preset back to SD.
+extern char sd_preset_path[FF_LFN_BUF];
+#endif
 #endif
 
 /*
diff --git a/plot.c b/plot.c
index e9c1992..9bbf119 100644
--- a/plot.c
+++ b/plot.c
@@ -394,6 +394,8 @@ value(const float v)
     return v + (30.0 + 20.0*log10f(sqrtf(50.0)));
   case U_DBUV:
     return v + (90.0 + 20.0*log10f(sqrtf(50.0)));
+  case U_DBV:
+    return v + (-30.0 + 20.0*log10f(sqrtf(50.0)));
   case U_VOLT:
 //  return powf(10.0, (v-30.0)/20.0) * sqrtf(50.0);                     // powf(10.0, v           /20.0) * powf(10, -30.0/20.0) * sqrtf(50)
     return expf(v*(logf(10.0)/20.0)) * (powf(10, -30.0/20.0)*sqrtf(50));//       expf(v*logf(10.0)/20.0) * powf(10, -30.0/20.0) * sqrtf(50)
@@ -418,6 +420,8 @@ to_dBm(const float v)
     return v - (30.0 + 20.0*log10f(sqrtf(50.0)));
   case U_DBUV:
     return v - (90.0 + 20.0*log10f(sqrtf(50.0)));
+  case U_DBV:
+    return v - (-30.0 + 20.0*log10f(sqrtf(50.0)));
   case U_VOLT:
 //  return log10f(v/(sqrtf(50.0)))* 20.0             + 30.0;
     return   logf(v/(sqrtf(50.0)))*(20.0/logf(10.0)) + 30.0;
@@ -485,6 +489,7 @@ trace_into_index_y_array(index_y_t *y, float *array, int points)
 #endif
     case U_DBMV: ref_shift = 30.0 + 20.0*log10f(sqrtf(50.0));break;
     case U_DBUV: ref_shift = 90.0 + 20.0*log10f(sqrtf(50.0));break;
+    case U_DBV:  ref_shift = -30.0 + 20.0*log10f(sqrtf(50.0));break;
     case U_VOLT: vmult = powf(10, -30.0/20.0) * sqrtf(50.0); mult = logf(10.0)/20.0;break;
     case U_VPP:  vmult = 2.828* powf(10, -30.0/20.0) * sqrtf(50.0); mult = logf(10.0)/20.0;break;
     case U_WATT: vmult = 1.0/1000.0;                         mult = logf(10.0)/10.0;break;
diff --git a/sa_core.c b/sa_core.c
index e72625d..4046a20 100644
--- a/sa_core.c
+++ b/sa_core.c
@@ -592,6 +592,9 @@ void update_min_max_freq(void)
 void reset_settings(int m)
 {
 //  strcpy((char *)spi_buffer, dummy);
+#ifdef __SD_FILE_BROWSER__
+  sd_preset_path[0] = 0;              // active preset no longer comes from SD
+#endif
   setting.mode = m;
   setting.sweep = false;
   disable_waterfall();
diff --git a/ui.c b/ui.c
index 7c7e237..7bd3cac 100644
--- a/ui.c
+++ b/ui.c
@@ -102,6 +102,22 @@ void ui_set_keypad_text(const char *text)
   plot_printf(kp_buf, sizeof(kp_buf), "%s", text);
 }
 
+// Set when kp_buf holds a default that the next keypad must start with instead
+// of an empty buffer, so a single ENTER accepts it unchanged
+static bool keypad_text_preset = false;
+
+#ifdef __SD_FILE_BROWSER__
+// Preset the keypad input with the first len characters of text
+static void ui_preset_keypad_text(const char *text, int len)
+{
+  if (len > (int)sizeof(kp_buf) - 1)
+    len = sizeof(kp_buf) - 1;
+  memcpy(kp_buf, text, len);
+  kp_buf[len] = 0;
+  keypad_text_preset = true;
+}
+#endif
+
 static uint8_t ui_mode = UI_NORMAL;
 static uint8_t keypad_mode;
 static char   *kp_help_text = NULL;
@@ -4351,6 +4367,12 @@ static const char *file_ext[] = {
   [FMT_BND_FILE] = "bnd",
 };
 
+#ifdef __SD_FILE_BROWSER__
+// Full path of the preset last loaded from SD, empty when the active preset did
+// not come from SD (startup preset, stored slot or factory defaults).
+char sd_preset_path[FF_LFN_BUF] = {0};
+#endif
+
 static void sa_save_file(uint8_t format);
 
 static UI_FUNCTION_CALLBACK(menu_sdcard_cb) {
@@ -5304,6 +5326,7 @@ static const menuitem_t menu_display[] = {
 static const menuitem_t menu_unit[] =
 {
   { MT_ADV_CALLBACK,U_DBM,   "dBm",             menu_unit_acb},
+  { MT_ADV_CALLBACK,U_DBV,   "dBV",             menu_unit_acb},
   { MT_ADV_CALLBACK,U_DBMV,  "dBmV",            menu_unit_acb},
   { MT_ADV_CALLBACK,U_DBUV,  "dB"S_MICRO"V",    menu_unit_acb},
   { MT_ADV_CALLBACK,U_VOLT,  "Vrms",            menu_unit_acb},
@@ -6190,7 +6213,8 @@ float my_round(float v)
   }
   return v;
 }
-const char * const unit_string[MAX_UNIT_TYPE*2] = { "dBm", "dBmV", "dB"S_MICRO"V", "RAW", "Vrms", "Vpp", "W", "dB", "dB", "dB", "RAW", "Vrms", "Vpp", "W" }; // unit + 6 is delta unit
+const char * const unit_string[MAX_UNIT_TYPE*2] = { "dBm", "dBmV", "dB"S_MICRO"V", "RAW", "Vrms", "Vpp", "W", "dBV",
+                                                    "dB",  "dB",   "dB",           "RAW", "Vrms", "Vpp", "W", "dB" }; // unit + MAX_UNIT_TYPE is delta unit
 
 //static const float scale_value[]={50000, 20000, 10000, 5000, 2000, 1000, 500, 200, 100, 50, 20,10,5,2,1,0.5,0.2,0.1,0.05,0.02,0.01,0.005,0.002, 0.001,0.0005,0.0002, 0.0001};
 //static const char * const scale_vtext[]= {"50000", "20000", "10000", "5000", "2000", "1000", "500", "200", "100", "50", "20","10","5","2","1","0.5","0.2","0.1","0.05","0.02","0.01", "0.005","0.002","0.001", "0.0005","0.0002","0.0001"};
@@ -7846,8 +7870,19 @@ ui_process_keypad(void)
 {
   int status;
   int keypads_last_index = keypads[0].pos - 1;
-  kp_buf[0] = 0;
+  // Keep a preset default only when the keypad is really shown, a remote menu
+  // invoke must not silently accept it
+  bool preset_text = keypad_text_preset && !in_menu_command;
+  keypad_text_preset = false;
+  if (!preset_text)
+    kp_buf[0] = 0;
   if (in_menu_command) return;
+  if (preset_text) {                          // show the default, ENTER accepts it as is
+    if (keypads[0].c == NUM_KEYBOARD)
+      draw_numeric_input(kp_buf);
+    else
+      draw_text_input(kp_buf);
+  }
   while (TRUE) {
     status = btn_check();
     if (status & (EVT_UP|EVT_DOWN)) {
@@ -8025,6 +8060,17 @@ static void sa_save_file(uint8_t format) {
 #endif
   }
   else {
+#ifdef __SD_FILE_BROWSER__
+    // Storing a preset: offer the SD preset it was loaded from as default name,
+    // so a single ENTER writes back to that same file
+    if (format == FMT_PRS_FILE && sd_preset_path[0]) {
+      int len = strlen(sd_preset_path);
+      int ext = strlen(file_ext[format]) + 1;             // ".prs"
+      if (len > ext && sd_preset_path[len - ext] == '.')  // keypad adds the extension back
+        len -= ext;
+      ui_preset_keypad_text(sd_preset_path, len);
+    }
+#endif
     ui_mode_keypad(KM_FILENAME);
     if (kp_buf[0] == 0) return;
     plot_printf(fs_filename, FF_LFN_BUF, "%s.%s", kp_buf, file_ext[format]);
diff --git a/vna_browser.c b/vna_browser.c
index 33f7312..0773ea8 100644
--- a/vna_browser.c
+++ b/vna_browser.c
@@ -322,6 +322,8 @@ static char cmd_buffer[256+128];
       set_scale(setting.scale);
       set_reflevel(setting.reflevel);
       set_level_meter_or_waterfall();
+      // Remember where this preset came from so storing it back can default to it
+      plot_printf(sd_preset_path, sizeof(sd_preset_path), "%s", fno.fname);
     }
     else error = "Format err";
   }