diff --git a/app/app.c b/app/app.c
index 92376b3..8dac70a 100644
--- a/app/app.c
+++ b/app/app.c
@@ -475,15 +475,30 @@ void APP_StartListening(FUNCTION_Type_t Function)
 
 void APP_SetFrequencyByStep(VFO_Info_t *pInfo, int8_t Step)
 {
-	uint32_t Frequency = pInfo->ConfigRX.Frequency + (Step * pInfo->StepFrequency);
+	uint32_t Frequency;
+
+	Frequency = pInfo->ConfigRX.Frequency + (Step * pInfo->StepFrequency);
+
+	if (pInfo->StepFrequency == 833)
+	{
+		const uint32_t Lower = LowerLimitFrequencyBandTable[pInfo->Band];
+		const uint32_t Delta = Frequency - Lower;
+		uint32_t       Base  = (Delta / 2500) * 2500;
+		const uint32_t Index = ((Delta - Base) % 2500) / 833;
+
+		if (Index == 2)
+			Base++;
+
+		Frequency = Lower + Base + (Index * 833);
+	}
 
-	if (Frequency < LowerLimitFrequencyBandTable[pInfo->Band])
-		Frequency = FREQUENCY_FloorToStep(UpperLimitFrequencyBandTable[pInfo->Band], pInfo->StepFrequency, LowerLimitFrequencyBandTable[pInfo->Band]);
-	else
 	if (Frequency > UpperLimitFrequencyBandTable[pInfo->Band])
-		Frequency = LowerLimitFrequencyBandTable[pInfo->Band];
-
-	pInfo->ConfigRX.Frequency = Frequency;
+		pInfo->ConfigRX.Frequency = LowerLimitFrequencyBandTable[pInfo->Band];
+	else
+	if (Frequency < LowerLimitFrequencyBandTable[pInfo->Band])
+		pInfo->ConfigRX.Frequency = FREQUENCY_FloorToStep(UpperLimitFrequencyBandTable[pInfo->Band], pInfo->StepFrequency, LowerLimitFrequencyBandTable[pInfo->Band]);
+	else
+		pInfo->ConfigRX.Frequency = Frequency;
 }
 
 static void FREQ_NextChannel(void)
@@ -614,6 +629,14 @@ void APP_CheckRadioInterrupts(void)
 		// fetch the interrupt status bits
 		interrupt_status_bits = BK4819_ReadRegister(BK4819_REG_02);
 
+		// 0 = no phase shift
+		// 1 = 120deg phase shift
+		// 2 = 180deg phase shift
+		// 3 = 240deg phase shift
+//		const uint8_t ctcss_shift = BK4819_GetCTCShift();
+//		if (ctcss_shift > 0)
+//			g_CTCSS_Lost = true;
+		
 		if (interrupt_status_bits & BK4819_REG_02_DTMF_5TONE_FOUND)
 		{
 			gDTMF_RequestPending = true;
diff --git a/app/menu.c b/app/menu.c
index 7dc0b84..5f82114 100644
--- a/app/menu.c
+++ b/app/menu.c
@@ -24,6 +24,8 @@
 #include "board.h"
 #include "bsp/dp32g030/gpio.h"
 #include "driver/backlight.h"
+#include "driver/bk4819.h"
+#include "driver/eeprom.h"
 #include "driver/gpio.h"
 #include "driver/keyboard.h"
 #include "frequencies.h"
@@ -61,9 +63,9 @@
 		VOICE_ID_INVALID,
 		VOICE_ID_BEEP_PROMPT,
 		VOICE_ID_TRANSMIT_OVER_TIME,
-//		#ifdef ENABLE_VOICE
+		#ifdef ENABLE_VOICE
 			VOICE_ID_VOICE_PROMPT,
-//		#endif
+		#endif
 		VOICE_ID_INVALID,
 		VOICE_ID_INVALID,
 		VOICE_ID_INVALID,
@@ -72,6 +74,9 @@
 		VOICE_ID_INVALID,
 		VOICE_ID_INVALID,
 		VOICE_ID_INVALID,
+		#ifdef ENABLE_COMPANDER
+			VOICE_ID_INVALID,
+		#endif
 		VOICE_ID_INVALID,
 		VOICE_ID_INVALID,
 		VOICE_ID_INVALID,
@@ -98,11 +103,16 @@
 		#endif
 		VOICE_ID_DELETE_CHANNEL,
 		VOICE_ID_INITIALISATION,
+
+		// hidden items
+		
 		VOICE_ID_INVALID,
 		VOICE_ID_INVALID,
 		VOICE_ID_INVALID,
 		VOICE_ID_INVALID,
 		VOICE_ID_INVALID,
+		VOICE_ID_INVALID,
+
 		VOICE_ID_INVALID
 	};
 #endif
@@ -127,7 +137,7 @@ void MENU_StopCssScan(void)
 	RADIO_SetupRegisters(true);
 }
 
-int MENU_GetLimits(uint8_t Cursor, uint8_t *pMin, uint8_t *pMax)
+int MENU_GetLimits(uint8_t Cursor, int32_t *pMin, int32_t *pMax)
 {
 	switch (Cursor)
 	{
@@ -304,7 +314,12 @@ int MENU_GetLimits(uint8_t Cursor, uint8_t *pMin, uint8_t *pMax)
 			*pMin = 1;
 			*pMax = 16;
 			break;
-			
+
+		case MENU_F_CALI:
+			*pMin = -1000;
+			*pMax = +1000;
+			break;
+		
 		default:
 			return -1;
 	}
@@ -314,8 +329,8 @@ int MENU_GetLimits(uint8_t Cursor, uint8_t *pMin, uint8_t *pMax)
 
 void MENU_AcceptSetting(void)
 {
-	uint8_t        Min;
-	uint8_t        Max;
+	int32_t        Min;
+	int32_t        Max;
 	uint8_t        Code;
 	FREQ_Config_t *pConfig = &gTxVfo->ConfigRX;
 
@@ -656,7 +671,28 @@ void MENU_AcceptSetting(void)
 			gRequestSaveSettings    = true;
 			gFlagReconfigureVfos    = true;
 			return;
-	
+
+		case MENU_F_CALI:
+			gEeprom.BK4819_XTAL_FREQ_LOW = gSubMenuSelection;
+			BK4819_WriteRegister(BK4819_REG_3B, 22656 + gEeprom.BK4819_XTAL_FREQ_LOW);
+			{
+				struct
+				{
+					int16_t  BK4819_XtalFreqLow;
+					uint16_t EEPROM_1F8A;
+					uint16_t EEPROM_1F8C;
+					uint8_t  VOLUME_GAIN;
+					uint8_t  DAC_GAIN;
+				} __attribute__((packed)) Misc;
+		
+				// radio 1 .. 04 00 46 00 50 00 2C 0E
+				// radio 2 .. 05 00 46 00 50 00 2C 0E
+				EEPROM_ReadBuffer(0x1F88, &Misc, 8);
+				Misc.BK4819_XtalFreqLow = gEeprom.BK4819_XTAL_FREQ_LOW;
+				EEPROM_WriteBuffer(0x1F88, &Misc);
+			}
+			return;
+			
 		default:
 			return;
 	}
@@ -666,13 +702,14 @@ void MENU_AcceptSetting(void)
 
 void MENU_SelectNextCode(void)
 {
-	uint8_t UpperLimit;
+	int32_t UpperLimit;
 
 	if (gMenuCursor == MENU_R_DCS)
 		UpperLimit = 208;
+		//UpperLimit = ARRAY_SIZE(DCS_Options);
 	else
 	if (gMenuCursor == MENU_R_CTCS)
-		UpperLimit = 50;
+		UpperLimit = ARRAY_SIZE(CTCSS_Options) - 1;
 	else
 		return;
 
@@ -707,11 +744,11 @@ void MENU_SelectNextCode(void)
 
 static void MENU_ClampSelection(int8_t Direction)
 {
-	uint8_t Min;
-	uint8_t Max;
+	int32_t Min;
+	int32_t Max;
 	if (!MENU_GetLimits(gMenuCursor, &Min, &Max))
 	{
-		uint8_t Selection = gSubMenuSelection;
+		int32_t Selection = gSubMenuSelection;
 		if (Selection < Min) Selection = Min;
 		else
 		if (Selection > Max) Selection = Max;
@@ -976,6 +1013,10 @@ void MENU_ShowCurrentSetting(void)
 		case MENU_SCREN:
 			gSubMenuSelection = gSetting_ScrambleEnable;
 			break;
+
+		case MENU_F_CALI:
+			gSubMenuSelection = gEeprom.BK4819_XTAL_FREQ_LOW;
+			break;
 	}
 }
 
@@ -1073,8 +1114,8 @@ static void MENU_Key_DIGITS(KEY_Code_t Key, bool bKeyPressed, bool bKeyHeld)
 		}
 		else
 		{
-			uint8_t Min;
-			uint8_t Max;
+			int32_t Min;
+			int32_t Max;
 
 			if (!MENU_GetLimits(gMenuCursor, &Min, &Max))
 			{
@@ -1322,12 +1363,16 @@ static void MENU_Key_UP_DOWN(bool bKeyPressed, bool bKeyHeld, int8_t Direction)
 		case MENU_1_CALL:
 			bCheckScanList = false;
 			break;
+
 		case MENU_SLIST2:
 			VFO = 1;
+
 			// Fallthrough
+
 		case MENU_SLIST1:
 			bCheckScanList = true;
 			break;
+
 		default:
 			MENU_ClampSelection(Direction);
 			gRequestDisplayScreen = DISPLAY_MENU;
@@ -1361,7 +1406,7 @@ void MENU_ProcessKeys(KEY_Code_t Key, bool bKeyPressed, bool bKeyHeld)
 			MENU_Key_MENU(bKeyPressed, bKeyHeld);
 			break;
 		case KEY_UP:
-			MENU_Key_UP_DOWN(bKeyPressed, bKeyHeld, 1);
+			MENU_Key_UP_DOWN(bKeyPressed, bKeyHeld,  1);
 			break;
 		case KEY_DOWN:
 			MENU_Key_UP_DOWN(bKeyPressed, bKeyHeld, -1);
diff --git a/app/menu.h b/app/menu.h
index a4fbe61..644be8d 100644
--- a/app/menu.h
+++ b/app/menu.h
@@ -19,7 +19,7 @@
 
 #include "driver/keyboard.h"
 
-int MENU_GetLimits(uint8_t Cursor, uint8_t *pMin, uint8_t *pMax);
+int MENU_GetLimits(uint8_t Cursor, int32_t *pMin, int32_t *pMax);
 void MENU_AcceptSetting(void);
 void MENU_SelectNextCode(void);
 void MENU_ShowCurrentSetting(void);
diff --git a/board.c b/board.c
index d4cd54a..d697913 100644
--- a/board.c
+++ b/board.c
@@ -52,8 +52,8 @@ static const uint32_t gDefaultFrequencyTable[] =
 	14500000,    //
 	14550000,    //
 	43300000,    //
-	43320000,    // 
-	43350000     // 
+	43320000,    //
+	43350000     //
 };
 
 // BAND1_50MHz
@@ -69,10 +69,10 @@ void BOARD_FLASH_Init(void)
 	FLASH_Init(FLASH_READ_MODE_1_CYCLE);
 	FLASH_ConfigureTrimValues();
 	SYSTEM_ConfigureClocks();
-	
+
 	overlay_FLASH_MainClock       = 48000000;
 	overlay_FLASH_ClockMultiplier = 48;
-	
+
 	FLASH_Init(FLASH_READ_MODE_2_CYCLE);
 }
 
@@ -379,7 +379,7 @@ void BOARD_EEPROM_Init(void)
 		gEeprom.NoaaChannel[0] = IS_NOAA_CHANNEL(Data[6])  ? Data[6] : NOAA_CHANNEL_FIRST;
 		gEeprom.NoaaChannel[1] = IS_NOAA_CHANNEL(Data[7])  ? Data[7] : NOAA_CHANNEL_FIRST;
 	#endif
-	
+
 #ifdef ENABLE_FMRADIO
 	{	// 0E88..0E8F
 		struct
@@ -389,7 +389,7 @@ void BOARD_EEPROM_Init(void)
 			uint8_t  IsMrMode;
 			uint8_t  Padding[8];
 		} __attribute__((packed)) FM;
-	
+
 		EEPROM_ReadBuffer(0x0E88, &FM, 8);
 		gEeprom.FM_LowerLimit = 760;
 		gEeprom.FM_UpperLimit = 1080;
@@ -401,7 +401,7 @@ void BOARD_EEPROM_Init(void)
 		gEeprom.FM_SelectedChannel = FM.SelectedChannel;
 		gEeprom.FM_IsMrMode        = (FM.IsMrMode < 2) ? FM.IsMrMode : false;
 	}
-	
+
 	// 0E40..0E67
 	EEPROM_ReadBuffer(0x0E40, gFM_Channels, sizeof(gFM_Channels));
 	FM_ConfigureChannelState();
@@ -430,7 +430,7 @@ void BOARD_EEPROM_Init(void)
 		EEPROM_ReadBuffer(0x0EA0, Data, 8);
 		gEeprom.VOICE_PROMPT = (Data[0] < 3) ? Data[0] : VOICE_PROMPT_ENGLISH;
 	#endif
-	
+
 	// 0EA8..0EAF
 	EEPROM_ReadBuffer(0x0EA8, Data, 8);
 	#ifdef ENABLE_ALARM
@@ -568,25 +568,29 @@ void BOARD_EEPROM_LoadMoreSettings(void)
 	//gEeprom.MIC_SENSITIVITY_TUNING = (Mic < 32) ? Mic : 15;
 	gEeprom.MIC_SENSITIVITY_TUNING = gMicGain_dB2[gEeprom.MIC_SENSITIVITY];
 
-	struct
 	{
-		int16_t  BK4819_XtalFreqLow;
-		uint16_t EEPROM_1F8A;
-		uint16_t EEPROM_1F8C;
-		uint8_t  VOLUME_GAIN;
-		uint8_t  DAC_GAIN;
-	} Misc;
+		struct
+		{
+			int16_t  BK4819_XtalFreqLow;
+			uint16_t EEPROM_1F8A;
+			uint16_t EEPROM_1F8C;
+			uint8_t  VOLUME_GAIN;
+			uint8_t  DAC_GAIN;
+		} __attribute__((packed)) Misc;
 
-	EEPROM_ReadBuffer(0x1F88, &Misc, 8);
-	gEeprom.BK4819_XTAL_FREQ_LOW = ((Misc.BK4819_XtalFreqLow + 1000) < 2000) ? Misc.BK4819_XtalFreqLow : 0;
+		// radio 1 .. 04 00 46 00 50 00 2C 0E
+		// radio 2 .. 05 00 46 00 50 00 2C 0E
+		EEPROM_ReadBuffer(0x1F88, &Misc, 8);
 
-	gEEPROM_1F8A = Misc.EEPROM_1F8A & 0x01FF;
-	gEEPROM_1F8C = Misc.EEPROM_1F8C & 0x01FF;
+		gEeprom.BK4819_XTAL_FREQ_LOW = (Misc.BK4819_XtalFreqLow >= -1000 && Misc.BK4819_XtalFreqLow <= 1000) ? Misc.BK4819_XtalFreqLow : 0;
+		gEEPROM_1F8A                 = Misc.EEPROM_1F8A & 0x01FF;
+		gEEPROM_1F8C                 = Misc.EEPROM_1F8C & 0x01FF;
+		gEeprom.VOLUME_GAIN          = (Misc.VOLUME_GAIN < 64) ? Misc.VOLUME_GAIN : 58;
+		gEeprom.DAC_GAIN             = (Misc.DAC_GAIN    < 16) ? Misc.DAC_GAIN    : 8;
 
-	gEeprom.VOLUME_GAIN = (Misc.VOLUME_GAIN < 64) ? Misc.VOLUME_GAIN : 58;
-	gEeprom.DAC_GAIN    = (Misc.DAC_GAIN    < 16) ? Misc.DAC_GAIN    : 8;
-
-	BK4819_WriteRegister(BK4819_REG_3B, gEeprom.BK4819_XTAL_FREQ_LOW + 22656);
+		BK4819_WriteRegister(BK4819_REG_3B, 22656 + gEeprom.BK4819_XTAL_FREQ_LOW);
+//		BK4819_WriteRegister(BK4819_REG_3C, gEeprom.BK4819_XTAL_FREQ_HIGH);
+	}
 }
 
 void BOARD_FactoryReset(bool bIsAll)
diff --git a/driver/bk4819.c b/driver/bk4819.c
index a323a42..66fbbde 100644
--- a/driver/bk4819.c
+++ b/driver/bk4819.c
@@ -1028,12 +1028,17 @@ uint8_t BK4819_GetDTMF_5TONE_Code(void)
 
 uint8_t BK4819_GetCDCSSCodeType(void)
 {
-	return (BK4819_ReadRegister(BK4819_REG_0C) >> 14) & 3;
+	return (BK4819_ReadRegister(BK4819_REG_0C) >> 14) & 3u;
+}
+
+uint8_t BK4819_GetCTCShift(void)
+{
+	return (BK4819_ReadRegister(BK4819_REG_0C) >> 12) & 3u;
 }
 
 uint8_t BK4819_GetCTCType(void)
 {
-	return (BK4819_ReadRegister(BK4819_REG_0C) >> 10) & 3;
+	return (BK4819_ReadRegister(BK4819_REG_0C) >> 10) & 3u;
 }
 
 void BK4819_SendFSKData(uint16_t *pData)
diff --git a/driver/bk4819.h b/driver/bk4819.h
index 178afa2..77950c9 100644
--- a/driver/bk4819.h
+++ b/driver/bk4819.h
@@ -137,6 +137,7 @@ void     BK4819_StopScan(void);
 uint8_t  BK4819_GetDTMF_5TONE_Code(void);
 
 uint8_t  BK4819_GetCDCSSCodeType(void);
+uint8_t  BK4819_GetCTCShift(void);
 uint8_t  BK4819_GetCTCType(void);
 
 void     BK4819_SendFSKData(uint16_t *pData);
diff --git a/firmware b/firmware
index 25d58d6..4753dc1 100644
Binary files a/firmware and b/firmware differ
diff --git a/firmware.bin b/firmware.bin
index dc4502e..b9c9e66 100644
Binary files a/firmware.bin and b/firmware.bin differ
diff --git a/firmware.packed.bin b/firmware.packed.bin
index a051c48..70275fc 100644
Binary files a/firmware.packed.bin and b/firmware.packed.bin differ
diff --git a/frequencies.c b/frequencies.c
index 6277aff..d2baa1a 100644
--- a/frequencies.c
+++ b/frequencies.c
@@ -148,7 +148,22 @@ uint8_t FREQUENCY_CalculateOutputPower(uint8_t TxpLow, uint8_t TxpMid, uint8_t T
 
 uint32_t FREQUENCY_FloorToStep(uint32_t Upper, uint32_t Step, uint32_t Lower)
 {
-	const uint32_t Index = (Upper - Lower) / Step;
+	uint32_t Index;
+
+	if (Step == 833)
+	{
+		const uint32_t Delta = Upper - Lower;
+		uint32_t       Base  = (Delta / 2500) * 2500;
+		const uint32_t Index = ((Delta - Base) % 2500) / 833;
+
+		if (Index == 2)
+			Base++;
+
+		return Lower + Base + (Index * 833);
+	}
+
+	Index = (Upper - Lower) / Step;
+
 	return Lower + (Step * Index);
 }
 
diff --git a/helper/boot.c b/helper/boot.c
index d8a4879..a8c06ab 100644
--- a/helper/boot.c
+++ b/helper/boot.c
@@ -66,7 +66,8 @@ void BOOT_ProcessMode(BOOT_Mode_t Mode)
 {
 	if (Mode == BOOT_MODE_F_LOCK)
 	{
-		gMenuListCount    += 6;               // enable the last 6 menu items
+		//gMenuListCount    += 6;               // enable the last 6 menu items
+		gMenuListCount    += 7;               // enable the last 7 menu items
 		gMenuCursor        = MENU_350TX;
 		gSubMenuSelection  = gSetting_350TX;
 		GUI_SelectNextDisplay(DISPLAY_MENU);
diff --git a/main.c b/main.c
index 5bae662..adc1018 100644
--- a/main.c
+++ b/main.c
@@ -116,7 +116,8 @@ void Main(void)
 		// count the number of menu list items
 		while (MenuList[gMenuListCount][0] != 0)
 			gMenuListCount++;
-		gMenuListCount -= 6;
+		//gMenuListCount -= 6;
+		gMenuListCount -= 7;
 
 		UI_DisplayWelcome();
 		BACKLIGHT_TurnOn();
diff --git a/misc.c b/misc.c
index b6c9993..e08a2dc 100644
--- a/misc.c
+++ b/misc.c
@@ -216,12 +216,15 @@ void NUMBER_ToDigits(uint32_t Value, char *pDigits)
 	pDigits[8] = 0;
 }
 
-uint8_t NUMBER_AddWithWraparound(uint8_t Base, int8_t Add, uint8_t LowerLimit, uint8_t UpperLimit)
+int32_t NUMBER_AddWithWraparound(int32_t Base, int32_t Add, int32_t LowerLimit, int32_t UpperLimit)
 {
 	Base += Add;
-	if (Base == 0xFF || Base < LowerLimit)
+
+	if (Base == 0x7fffffff || Base < LowerLimit)
 		return UpperLimit;
+
 	if (Base > UpperLimit)
 		return LowerLimit;
+
 	return Base;
 }
diff --git a/misc.h b/misc.h
index fe3ea64..fd09a2a 100644
--- a/misc.h
+++ b/misc.h
@@ -239,7 +239,7 @@ extern uint8_t               gIsLocked;
 
 void    NUMBER_Get(char *pDigits, uint32_t *pInteger);
 void    NUMBER_ToDigits(uint32_t Value, char *pDigits);
-uint8_t NUMBER_AddWithWraparound(uint8_t Base, int8_t Add, uint8_t LowerLimit, uint8_t UpperLimit);
+int32_t NUMBER_AddWithWraparound(int32_t Base, int32_t Add, int32_t LowerLimit, int32_t UpperLimit);
 
 #endif
 
diff --git a/ui/menu.c b/ui/menu.c
index c1d4b58..b442397 100644
--- a/ui/menu.c
+++ b/ui/menu.c
@@ -15,10 +15,12 @@
  */
 
 #include <string.h>
+#include <stdlib.h>  // abs()
 
 #include "app/dtmf.h"
 #include "bitmaps.h"
 #include "dcs.h"
+#include "driver/bk4819.h"
 #include "driver/eeprom.h"   // EEPROM_ReadBuffer()
 #include "driver/st7565.h"
 #include "external/printf/printf.h"
@@ -107,7 +109,9 @@ const char MenuList[][7] =
 	"500-TX",    // was "500TX"
 	"350-EN",    // was "350EN"
 	"SCR-EN",    // was "SCREN"
-	
+
+	"F-CALI",    // reference xtal calibration
+
 	""           // end of list
 };
 
@@ -241,10 +245,10 @@ const char gSubMenu_F_LOCK[6][4] =
 	"438"
 };
 
-bool     gIsInSubMenu;
-uint8_t  gMenuCursor;
-int8_t   gMenuScrollDirection;
-uint32_t gSubMenuSelection;
+bool    gIsInSubMenu;
+uint8_t gMenuCursor;
+int8_t  gMenuScrollDirection;
+int32_t gSubMenuSelection;
 
 void UI_DisplayMenu(void)
 {
@@ -255,7 +259,7 @@ void UI_DisplayMenu(void)
 	memset(gFrameBuffer, 0, sizeof(gFrameBuffer));
 
 	for (i = 0; i < 3; i++)
-		if (gMenuCursor || i)
+		if (gMenuCursor > 0 || i > 0)
 			if ((gMenuListCount - 1) != gMenuCursor || i != 2)
 				UI_PrintString(MenuList[gMenuCursor + i - 1], 0, 0, i * 2, 8);
 
@@ -274,7 +278,7 @@ void UI_DisplayMenu(void)
 			gFrameBuffer[i][49] = 0xFF;
 		}
 	#else
-		// a nicer less intense thinner dotted line
+		// a less intense thinner dotted line
 		for (i = 0; i < 6; i++)
 			gFrameBuffer[i][49] = 0xAA;
 	#endif
@@ -283,7 +287,7 @@ void UI_DisplayMenu(void)
 		NUMBER_ToDigits(1 + gMenuCursor, String);
 		UI_DisplaySmallDigits(2, String + 6, 33, 6, false);
 	#else
-		sprintf(String, "%2u.%u", 1u + gMenuCursor, gMenuListCount);
+		sprintf(String, "%2u.%u", 1 + gMenuCursor, gMenuListCount);
 		UI_PrintStringSmall(String, 8, 0, 6);
 	#endif
 
@@ -295,7 +299,7 @@ void UI_DisplayMenu(void)
 	switch (gMenuCursor)
 	{
 		case MENU_SQL:
-			sprintf(String, "%u", gSubMenuSelection);
+			sprintf(String, "%d", gSubMenuSelection);
 			break;
 
 		case MENU_MIC:
@@ -306,13 +310,13 @@ void UI_DisplayMenu(void)
 			break;
 
 		case MENU_STEP:
-			sprintf(String, "%u.%02uKHz", StepFrequencyTable[gSubMenuSelection] / 100, StepFrequencyTable[gSubMenuSelection] % 100);
+			sprintf(String, "%d.%02uKHz", StepFrequencyTable[gSubMenuSelection] / 100, abs(StepFrequencyTable[gSubMenuSelection]) % 100);
 			break;
-	
+
 		case MENU_TXP:
 			strcpy(String, gSubMenu_TXP[gSubMenuSelection]);
 			break;
-	
+
 		case MENU_R_DCS:
 		case MENU_T_DCS:
 			if (gSubMenuSelection == 0)
@@ -323,7 +327,7 @@ void UI_DisplayMenu(void)
 			else
 				sprintf(String, "D%03oI", DCS_Options[gSubMenuSelection - 105]);
 			break;
-	
+
 		case MENU_R_CTCS:
 		case MENU_T_CTCS:
 			if (gSubMenuSelection == 0)
@@ -331,15 +335,15 @@ void UI_DisplayMenu(void)
 			else
 				sprintf(String, "%u.%uHz", CTCSS_Options[gSubMenuSelection - 1] / 10, CTCSS_Options[gSubMenuSelection - 1] % 10);
 			break;
-	
+
 		case MENU_SFT_D:
 			strcpy(String, gSubMenu_SFT_D[gSubMenuSelection]);
 			break;
-	
+
 		case MENU_OFFSET:
 			if (!gIsInSubMenu || gInputBoxIndex == 0)
 			{
-				sprintf(String, "%u.%05u", gSubMenuSelection / 100000, gSubMenuSelection % 100000);
+				sprintf(String, "%d.%05u", gSubMenuSelection / 100000, abs(gSubMenuSelection) % 100000);
 				break;
 			}
 
@@ -355,26 +359,26 @@ void UI_DisplayMenu(void)
 			String[11] = 0;
 
 			break;
-	
+
 		case MENU_W_N:
 			strcpy(String, gSubMenu_W_N[gSubMenuSelection]);
 			break;
-	
+
 		case MENU_SCR:
 		case MENU_VOX:
 			if (gSubMenuSelection == 0)
 				strcpy(String, "OFF");
 			else
-				sprintf(String, "%u", gSubMenuSelection);
+				sprintf(String, "%d", gSubMenuSelection);
 			break;
-	
+
 		case MENU_ABR:
 			#if 0
 				if (gSubMenuSelection == 0)
 					strcpy(String, "OFF");
 				else
 				if (gSubMenuSelection < 5)
-					sprintf(String, "%u sec", gSubMenuSelection * 10);
+					sprintf(String, "%d sec", gSubMenuSelection * 10);
 				else
 					strcpy(String, "ON");
 			#else
@@ -390,11 +394,11 @@ void UI_DisplayMenu(void)
 				}
 			#endif
 			break;
-	
+
 		case MENU_AM:
 			strcpy(String, (gSubMenuSelection == 0) ? "FM" : "AM");
 			break;
-			
+
 		case MENU_AUTOLK:
 			strcpy(String, (gSubMenuSelection == 0) ? "OFF" : "AUTO");
 			break;
@@ -419,91 +423,88 @@ void UI_DisplayMenu(void)
 		case MENU_SCREN:
 			strcpy(String, gSubMenu_OFF_ON[gSubMenuSelection]);
 			break;
-	
+
 		case MENU_MEM_CH:
 		case MENU_1_CALL:
 		case MENU_DEL_CH:
-			UI_GenerateChannelStringEx(
-				String,
-				RADIO_CheckValidChannel((uint16_t)gSubMenuSelection, false, 0),
-				(uint8_t)gSubMenuSelection);
+			UI_GenerateChannelStringEx(String, RADIO_CheckValidChannel(gSubMenuSelection, false, 0), gSubMenuSelection);
 			break;
-	
+
 		case MENU_SAVE:
 			strcpy(String, gSubMenu_SAVE[gSubMenuSelection]);
 			break;
-	
+
 		case MENU_TDR:
 		case MENU_XB:
 			strcpy(String, gSubMenu_CHAN[gSubMenuSelection]);
 			break;
-	
+
 		case MENU_TOT:
 			if (gSubMenuSelection == 0)
 				strcpy(String, "OFF");
 			else
-				sprintf(String, "%umin", gSubMenuSelection);
+				sprintf(String, "%dmin", gSubMenuSelection);
 			break;
-	
+
 		#ifdef ENABLE_VOICE
 			case MENU_VOICE:
 				strcpy(String, gSubMenu_VOICE[gSubMenuSelection]);
 				break;
 		#endif
-		
+
 		case MENU_SC_REV:
 			strcpy(String, gSubMenu_SC_REV[gSubMenuSelection]);
 			break;
-	
+
 		case MENU_MDF:
 			strcpy(String, gSubMenu_MDF[gSubMenuSelection]);
 			break;
-	
+
 		case MENU_RP_STE:
 			if (gSubMenuSelection == 0)
 				strcpy(String, "OFF");
 			else
-				sprintf(String, "%u*100ms", gSubMenuSelection);
+				sprintf(String, "%d*100ms", gSubMenuSelection);
 			break;
-	
+
 		case MENU_S_LIST:
 			sprintf(String, "LIST%u", gSubMenuSelection);
 			break;
-	
+
 		#ifdef ENABLE_ALARM
 			case MENU_AL_MOD:
 				sprintf(String, gSubMenu_AL_MOD[gSubMenuSelection]);
 				break;
 		#endif
-		
+
 		case MENU_ANI_ID:
 			strcpy(String, gEeprom.ANI_DTMF_ID);
 			break;
-	
+
 		case MENU_UPCODE:
 			strcpy(String, gEeprom.DTMF_UP_CODE);
 			break;
-	
+
 		case MENU_DWCODE:
 			strcpy(String, gEeprom.DTMF_DOWN_CODE);
 			break;
-	
+
 		case MENU_D_RSP:
 			strcpy(String, gSubMenu_D_RSP[gSubMenuSelection]);
 			break;
-	
+
 		case MENU_D_HOLD:
-			sprintf(String, "%us", gSubMenuSelection);
+			sprintf(String, "%ds", gSubMenuSelection);
 			break;
-	
+
 		case MENU_D_PRE:
-			sprintf(String, "%u*10ms", gSubMenuSelection);
+			sprintf(String, "%d*10ms", gSubMenuSelection);
 			break;
-	
+
 		case MENU_PTT_ID:
 			strcpy(String, gSubMenu_PTT_ID[gSubMenuSelection]);
 			break;
-	
+
 		case MENU_D_LIST:
 			gIsDtmfContactValid = DTMF_GetContact((int)gSubMenuSelection - 1, Contact);
 			if (!gIsDtmfContactValid)
@@ -511,26 +512,42 @@ void UI_DisplayMenu(void)
 			else
 				memcpy(String, Contact, 8);
 			break;
-	
+
 		case MENU_PONMSG:
 			strcpy(String, gSubMenu_PONMSG[gSubMenuSelection]);
 			break;
-	
+
 		case MENU_ROGER:
 			strcpy(String, gSubMenu_ROGER[gSubMenuSelection]);
 			break;
-	
+
 		case MENU_VOL:
 			sprintf(String, "%u.%02uV", gBatteryVoltageAverage / 100, gBatteryVoltageAverage % 100);
 			break;
-	
+
 		case MENU_RESET:
 			strcpy(String, gSubMenu_RESET[gSubMenuSelection]);
 			break;
-	
+
 		case MENU_F_LOCK:
 			strcpy(String, gSubMenu_F_LOCK[gSubMenuSelection]);
 			break;
+
+		case MENU_F_CALI:
+			{
+				sprintf(String, "%d", gSubMenuSelection);
+				UI_PrintString(String, 50, 127, 1, 8);
+
+				const uint32_t value = 22656 + gSubMenuSelection;
+				//gEeprom.BK4819_XTAL_FREQ_LOW = gSubMenuSelection;
+				BK4819_WriteRegister(BK4819_REG_3B, value);
+
+				const uint32_t xtal_Hz = (0x4f0000u + value) * 5;
+				sprintf(String, "%u.%06u", xtal_Hz / 1000000, xtal_Hz % 1000000);
+				UI_PrintString(String, 50, 127, 3, 8);
+				UI_PrintString("MHz",  50, 127, 5, 8);
+			}
+			break;
 	}
 
 	if (gMenuCursor == MENU_AM)
@@ -565,6 +582,7 @@ void UI_DisplayMenu(void)
 		UI_PrintString("MHz",  50, 127, 3, 8);
 	}
 	else
+	if (gMenuCursor != MENU_F_CALI)
 	{
 		UI_PrintString(String, 50, 127, 2, 8);
 	}
@@ -631,7 +649,7 @@ void UI_DisplayMenu(void)
 	    gMenuCursor == MENU_D_LIST)
 	{
 		unsigned int Offset;
-		NUMBER_ToDigits((uint8_t)gSubMenuSelection, String);
+		NUMBER_ToDigits(gSubMenuSelection, String);
 		Offset = (gMenuCursor == MENU_D_LIST) ? 2 : 3;
 		UI_DisplaySmallDigits(Offset, String + (8 - Offset), 105, 0, false);
 	}
@@ -643,7 +661,7 @@ void UI_DisplayMenu(void)
 		if (gSubMenuSelection == 0xFF)
 			strcpy(String, "NULL");
 		else
-			UI_GenerateChannelStringEx(String, true, (uint8_t)gSubMenuSelection);
+			UI_GenerateChannelStringEx(String, true, gSubMenuSelection);
 
 		if (gSubMenuSelection == 0xFF || !gEeprom.SCAN_LIST_ENABLED[i])
 		{
diff --git a/ui/menu.h b/ui/menu.h
index eebcefb..fdf17a3 100644
--- a/ui/menu.h
+++ b/ui/menu.h
@@ -82,12 +82,17 @@ enum
 	#endif
 	MENU_DEL_CH,
 	MENU_RESET,
+
+	// items after here are normally hidden
+
 	MENU_350TX,
 	MENU_F_LOCK,
 	MENU_200TX,
 	MENU_500TX,
 	MENU_350EN,
-	MENU_SCREN
+	MENU_SCREN,
+
+	MENU_F_CALI   // reference xtal calibration
 };
 
 extern const char MenuList[][7];
@@ -121,9 +126,8 @@ extern bool       gIsInSubMenu;
 
 extern uint8_t    gMenuCursor;
 extern int8_t     gMenuScrollDirection;
-extern uint32_t   gSubMenuSelection;
+extern int32_t    gSubMenuSelection;
 
 void UI_DisplayMenu(void);
 
 #endif
-