diff --git a/vna_system/core/processors/base_processor.py b/vna_system/core/processors/base_processor.py
index a68da91..6baa78d 100644
--- a/vna_system/core/processors/base_processor.py
+++ b/vna_system/core/processors/base_processor.py
@@ -562,6 +562,26 @@ class BaseProcessor:
     # --------------------------------------------------------------------- #
     # History Export/Import
     # --------------------------------------------------------------------- #
+    def _make_json_serializable(self, obj: Any) -> Any:
+        """
+        Recursively convert non-serializable objects to JSON-compatible types.
+
+        Handles Enums, custom objects, etc.
+        """
+        from enum import Enum
+
+        if isinstance(obj, Enum):
+            return obj.value
+        elif isinstance(obj, dict):
+            return {key: self._make_json_serializable(value) for key, value in obj.items()}
+        elif isinstance(obj, (list, tuple)):
+            return [self._make_json_serializable(item) for item in obj]
+        elif hasattr(obj, '__dict__'):
+            # Custom object - try to serialize its dict
+            return self._make_json_serializable(obj.__dict__)
+        else:
+            return obj
+
     def export_history_data(self) -> list[dict[str, Any]]:
         """
         Export sweep history in JSON-serializable format.
@@ -578,13 +598,16 @@ class BaseProcessor:
                 calibrated_data = entry["calibrated_data"]
                 reference_data = entry.get("reference_data")
 
+                # Convert vna_config to fully serializable format
+                vna_config = self._make_json_serializable(entry.get("vna_config", {}))
+
                 exported.append({
                     "sweep_number": sweep_data.sweep_number if sweep_data else None,
                     "timestamp": entry.get("timestamp"),
                     "sweep_points": sweep_data.points if sweep_data else [],
                     "calibrated_points": calibrated_data.points if calibrated_data else [],
                     "reference_points": reference_data.points if reference_data else [],
-                    "vna_config": entry.get("vna_config", {}),
+                    "vna_config": vna_config,
                 })
 
             return exported