diff --git a/HPSDRProtocol.pas b/HPSDRProtocol.pas
index 84da714..c480085 100644
--- a/HPSDRProtocol.pas
+++ b/HPSDRProtocol.pas
@@ -440,13 +440,17 @@ end;
 
 function ADCToSupplyVolts(RawADC: Word; BoardType: Integer): Double;
 begin
-  // Board 0 (Atlas) has no supply voltage measurement (protocol: "not Atlas bus systems")
-  // Boards 1,2,3 (Hermes/Angelia): V = ADC/4095 * 3.3  (Appendix A)
-  // Boards 4,5   (Orion):          V = ADC/4095 * 5.0  (Appendix A)
+  // Protocol Appendix A gives the ADC reference voltage only.
+  // The PCB voltage divider (from Thetis source) must also be applied.
+  // Board 0 (Atlas): no supply voltage measurement.
+  // Boards 1,2,3 (Hermes/Angelia): Vref=3.3V, PCB divider R1=4.7kΩ/R2=0.82kΩ.
+  // Board 5 (Orion MkII): Vref=5.0V, PCB divider R1=22kΩ/R2=1.1kΩ.
+  //   NOTE: for board 5 caller must pass UserADC0, not supply_volts bytes.
+  // Board 4 (Orion) and others: not available (return -1).
   case BoardType of
-    1, 2, 3: Result := (RawADC / 4095.0) * 3.3;
-    4, 5:    Result := (RawADC / 4095.0) * 5.0;
-  else       Result := -1.0;  // not documented or not applicable
+    1, 2, 3: Result := (RawADC / 4095.0) * 3.3 * ((4.7 + 0.82) / 0.82);
+    5:       Result := (RawADC / 4095.0) * 5.0 * ((22.0 + 1.0) / 1.1);
+  else       Result := -1.0;
   end;
 end;
 
diff --git a/MainForm.pas b/MainForm.pas
index 1bb311a..be3f9c7 100644
--- a/MainForm.pas
+++ b/MainForm.pas
@@ -2461,8 +2461,16 @@ begin
   ExcPwr  := (Status.ExciterPwr0Hi shl 8) or Status.ExciterPwr0Lo;
   FwdPwr  := (Status.FwdPwrAlex0Hi shl 8) or Status.FwdPwrAlex0Lo;
   RevPwr  := (Status.RevPwrAlex0Hi shl 8) or Status.RevPwrAlex0Lo;
-  SupplyV := ADCToSupplyVolts((Status.SupplyVoltsHi shl 8) or Status.SupplyVoltsLo,
-               FNetwork.Device.BoardType);
+  // Board 5 (Orion MkII) measures supply voltage via UserADC0 (bytes 57-58),
+  // not the supply_volts field (bytes 49-50) — matching Thetis behaviour.
+  if FNetwork.Device.BoardType = 5 then
+    SupplyV := ADCToSupplyVolts(
+                 (Status.UserADC0Hi shl 8) or Status.UserADC0Lo,
+                 FNetwork.Device.BoardType)
+  else
+    SupplyV := ADCToSupplyVolts(
+                 (Status.SupplyVoltsHi shl 8) or Status.SupplyVoltsLo,
+                 FNetwork.Device.BoardType);
   // FLastSMeter обновляется только из WDSP (GetSMeterDBm) в SpectrumTimerTick —
   // ExciterPwr это мощность TX, не уровень принятого сигнала.
   FwdW := ADCToWatts100(FwdPwr);