diff --git a/auto_rx/autorx/config.py b/auto_rx/autorx/config.py
index 9a50ecc..c93dd74 100644
--- a/auto_rx/autorx/config.py
+++ b/auto_rx/autorx/config.py
@@ -799,7 +799,7 @@ def read_auto_rx_config(filename, no_sdr_test=False):
                 sdr_port=auto_rx_config["sdr_port"],
                 ss_iq_path=auto_rx_config["ss_iq_path"],
                 ss_power_path=auto_rx_config["ss_power_path"],
-                check_freq=auto_rx_config["min_freq"] * 1e6,
+                check_freq=(auto_rx_config["min_freq"]+(auto_rx_config["max_freq"]-auto_rx_config["min_freq"])/2.0) * 1e6,
             )
 
             if not _sdr_ok:
diff --git a/auto_rx/autorx/scan.py b/auto_rx/autorx/scan.py
index a8b32e8..b229a1d 100644
--- a/auto_rx/autorx/scan.py
+++ b/auto_rx/autorx/scan.py
@@ -767,7 +767,7 @@ class SondeScanner(object):
             sdr_hostname = self.sdr_hostname, 
             sdr_port = self.sdr_port,
             ss_iq_path = self.ss_iq_path,
-            check_freq = self.min_freq * 1e6
+            check_freq = (self.min_freq + (self.max_freq-self.min_freq)/2.0) * 1e6
             )
 
         if not _sdr_ok:
@@ -830,7 +830,7 @@ class SondeScanner(object):
                         sdr_hostname = self.sdr_hostname, 
                         sdr_port = self.sdr_port,
                         ss_iq_path = self.ss_iq_path,
-                        check_freq = self.min_freq * 1e6
+                        check_freq = (self.min_freq + (self.max_freq-self.min_freq)/2.0) * 1e6
                         )
 
                     if not _sdr_ok: