diff --git a/libraries/SX1278FSK/SX1278FSK.cpp b/libraries/SX1278FSK/SX1278FSK.cpp
index d6500ce..c7b5e29 100644
--- a/libraries/SX1278FSK/SX1278FSK.cpp
+++ b/libraries/SX1278FSK/SX1278FSK.cpp
@@ -330,6 +330,7 @@ uint8_t SX1278FSK::setFrequency(float freq) {
 
 	// set mode to FSK STANDBY 
 	writeRegister(REG_OP_MODE, FSK_STANDBY_MODE);
+	freq += sonde.config.freqofs;  // manual frequency correction
 
 	uint32_t frf = freq * 1.0 * (1<<19) / SX127X_CRYSTAL_FREQ;
 	writeRegister(REG_FRF_MSB, (frf&0xff0000)>>16);
diff --git a/libraries/SondeLib/Sonde.cpp b/libraries/SondeLib/Sonde.cpp
index 8b024e9..dedeee5 100644
--- a/libraries/SondeLib/Sonde.cpp
+++ b/libraries/SondeLib/Sonde.cpp
@@ -4,8 +4,10 @@
 #include "Sonde.h"
 #include "RS41.h"
 #include "DFM.h"
+#include "SX1278FSK.h"
 
 extern U8X8_SSD1306_128X64_NONAME_SW_I2C *u8x8;
+extern SX1278FSK sx1278;
 
 //SondeInfo si = { STYPE_RS41, 403.450, "P1234567", true, 48.1234, 14.9876, 543, 3.97, -0.5, true, 120 };
 const char *sondeTypeStr[5] = { "DFM6", "DFM9", "RS41" };
@@ -75,6 +77,8 @@ Sonde::Sonde() {
 	config.timer=0;
 	config.marker=0;
 	config.norx_timeout=0;
+	config.showafc=0;
+	config.freqofs=0;
 	config.rs41.agcbw=25;
 	config.rs41.rxbw=12;
 	config.udpfeed.active = 1;
@@ -141,7 +145,9 @@ void Sonde::setConfig(const char *cfg) {
 	} else if(strcmp(cfg,"norx_timeout")==0) {
 		config.norx_timeout = atoi(val);					
 	} else if(strcmp(cfg,"showafc")==0) {
-		config.showafc = atoi(val);					
+		config.showafc = atoi(val);
+	} else if(strcmp(cfg,"freqofs")==0) {
+		config.freqofs = atoi(val);
 	} else if(strcmp(cfg,"rs41.agcbw")==0) {
 		config.rs41.agcbw = atoi(val);
 	} else if(strcmp(cfg,"rs41.rxbw")==0) {
@@ -246,6 +252,11 @@ void Sonde::setup() {
 		dfm.setFrequency(sondeList[currentSonde].freq * 1000000);
 		break;
 	}
+	// debug
+	float afcbw = sx1278.getAFCBandwidth();
+	float rxbw = sx1278.getRxBandwidth();
+	Serial.printf("AFC BW: %f  RX BW: %f\n", afcbw, rxbw);
+
 }
 int Sonde::receiveFrame() {
 	int ret;
diff --git a/libraries/SondeLib/Sonde.h b/libraries/SondeLib/Sonde.h
index 2051d55..f35a8b8 100644
--- a/libraries/SondeLib/Sonde.h
+++ b/libraries/SondeLib/Sonde.h
@@ -35,6 +35,7 @@ typedef struct st_rdzconfig {
 	int norx_timeout;		// Time after which rx mode switches to scan mode (without rx signal)
 	int noisefloor;			// for spectrum display
 	int showafc;			// show afc value in rx screen
+	int freqofs;			// frequency offset (tuner config = rx frequency + freqofs) in Hz
 	char call[9];			// APRS callsign
 	char passcode[9];		// APRS passcode
 	struct st_rs41config rs41;	// configuration options specific for RS41 receiver