Remove redundant trigger('change') call in setFrequency

The frequency change event is already triggered conditionally when
fromWaterfall=false, so the unconditional trigger on the first line
was redundant and could cause the change handler to execute twice.

assets/js/dxwaterfall.js

@@ -6248,9 +6248,10 @@ function setFrequency(frequencyInKHz, fromWaterfall) {
     }
 
     // Update frequency field with value in Hz
-    $('#frequency').val(frequencyInKHz * 1000).trigger('change');
+    $('#frequency').val(frequencyInKHz * 1000);
 
-    // Also trigger change event unless called from waterfall
+    // Trigger change event to update calculated fields and unit display
+    // Skip trigger when called from waterfall to prevent recursive updates
     if (!fromWaterfall) {
         $('#frequency').trigger('change');
     }