diff --git a/driver/bk4819.c b/driver/bk4819.c
index 45efa03..0090c2e 100644
--- a/driver/bk4819.c
+++ b/driver/bk4819.c
@@ -1183,7 +1183,25 @@ void BK4819_TransmitTone(bool bLocalLoopback, uint32_t Frequency)
 {
 	BK4819_EnterTxMute();
 
-	BK4819_WriteRegister(BK4819_REG_70, 0 | BK4819_REG_70_MASK_ENABLE_TONE1 | (96U << BK4819_REG_70_SHIFT_TONE1_TUNING_GAIN));
+	// REG_70 <15>   0 Enable TONE1
+	//               1 = Enable
+	//               0 = Disable
+	//
+	// REG_70 <14:8> 0 TONE1 tuning gain
+	//               0 ~ 127
+	//
+	// REG_70 <7>    0 Enable TONE2
+	//               1 = Enable
+	//               0 = Disable
+	//
+	// REG_70 <6:0>  0 TONE2/FSK tuning gain
+	//               0 ~ 127
+	//
+	// set the tone amplitude
+	//
+//	BK4819_WriteRegister(BK4819_REG_70, BK4819_REG_70_MASK_ENABLE_TONE1 | (96u << BK4819_REG_70_SHIFT_TONE1_TUNING_GAIN));
+	BK4819_WriteRegister(BK4819_REG_70, BK4819_REG_70_MASK_ENABLE_TONE1 | (50u << BK4819_REG_70_SHIFT_TONE1_TUNING_GAIN));
+
 	BK4819_WriteRegister(BK4819_REG_71, scale_freq(Frequency));
 
 	BK4819_SetAF(bLocalLoopback ? BK4819_AF_BEEP : BK4819_AF_MUTE);
diff --git a/firmware.bin b/firmware.bin
index 88c03db..d2c5ec5 100644
Binary files a/firmware.bin and b/firmware.bin differ
diff --git a/firmware.packed.bin b/firmware.packed.bin
index bd84615..8576750 100644
Binary files a/firmware.packed.bin and b/firmware.packed.bin differ