feat(dmr): default tuning step to 12.5 kHz

RadioController.pas

@@ -2753,6 +2753,11 @@ begin
   end;
   FFMStepOn  := B.FMStepOn;
   FFMStepIdx := EnsureRange(B.FMStepIdx, 0, 3);
+  if FMode = MODE_DMR then
+  begin
+    FFMStepOn := True;
+    FFMStepIdx := 1;  // DMR default raster: 12.5 kHz
+  end;
   FFMRptDir      := B.FMRptDir;
   FFMRptOffsetHz := B.FMRptOffsetHz;
   if FFMRptOffsetHz <= 0 then FFMRptOffsetHz := RptDefaultOffsetHz(B.VfoA);
@@ -3110,6 +3115,15 @@ end;
 procedure TRadioController.SetMode(M: Integer);
 begin
   FMode := M;
+  // DMR channels use a 12.5 kHz raster by default. Keep the ordinary STEP
+  // controls enabled so the operator can select another raster afterwards.
+  if FMode = MODE_DMR then
+  begin
+    FFMStepOn := True;
+    FFMStepIdx := 1;  // 12.5 kHz
+    Changed(rfFMStep);
+    Changed(rfFMStepIdx);
+  end;
   // Entering receive-only DMR on the selected main TX source immediately
   // releases an existing carrier. SetTune(False) also releases MOX.
   if ActiveTXMode = MODE_DMR then