diff --git a/companion/src/datamodels/compounditemmodels.cpp b/companion/src/datamodels/compounditemmodels.cpp
index 29dc9b8f5..7ee049d1f 100644
--- a/companion/src/datamodels/compounditemmodels.cpp
+++ b/companion/src/datamodels/compounditemmodels.cpp
@@ -118,7 +118,7 @@ RawSourceItemModel::RawSourceItemModel(const GeneralSettings * const generalSett
   addItems(SOURCE_TYPE_CYC,            RawSource::SourcesGroup,  CPN_MAX_CYC);
   addItems(SOURCE_TYPE_PPM,            RawSource::SourcesGroup,  firmware->getCapability(TrainerInputs));
   addItems(SOURCE_TYPE_CH,             RawSource::SourcesGroup,  firmware->getCapability(Outputs));
-  addItems(SOURCE_TYPE_SPECIAL,        RawSource::TelemGroup,    6);
+  addItems(SOURCE_TYPE_SPECIAL,        RawSource::TelemGroup,    SOURCE_TYPE_SPECIAL_COUNT);
   addItems(SOURCE_TYPE_TELEMETRY,      RawSource::TelemGroup,    firmware->getCapability(Sensors) * 3);
   addItems(SOURCE_TYPE_GVAR,           RawSource::GVarsGroup,    firmware->getCapability(Gvars));
 }
diff --git a/companion/src/firmwares/customfunctiondata.cpp b/companion/src/firmwares/customfunctiondata.cpp
index f60f1c74a..293bdd6db 100644
--- a/companion/src/firmwares/customfunctiondata.cpp
+++ b/companion/src/firmwares/customfunctiondata.cpp
@@ -84,7 +84,7 @@ QString CustomFunctionData::funcToString(const AssignFunc func, const ModelData
   else if (func == FuncReset)
     return tr("Reset");
   else if (func >= FuncSetTimer1 && func <= FuncSetTimerLast)
-    return tr("Set %1").arg(RawSource(SOURCE_TYPE_SPECIAL, SOURCE_TYPE_SPECIAL_TIMER1_IDX + func - FuncSetTimer1).toString(model));
+    return tr("Set %1").arg(RawSource(SOURCE_TYPE_SPECIAL, SOURCE_TYPE_SPECIAL_FIRST_TIMER + func - FuncSetTimer1).toString(model));
   else if (func == FuncVario)
     return tr("Vario");
   else if (func == FuncPlayPrompt)
@@ -249,7 +249,7 @@ QString CustomFunctionData::resetToString(const int value, const ModelData * mod
 
   if (value < step) {
     if (value < firmware->getCapability(Timers))
-      return RawSource(SOURCE_TYPE_SPECIAL, value + SOURCE_TYPE_SPECIAL_TIMER1_IDX).toString(model);
+      return RawSource(SOURCE_TYPE_SPECIAL, value + SOURCE_TYPE_SPECIAL_FIRST_TIMER).toString(model);
     else
       return QString(CPN_STR_UNKNOWN_ITEM);
   }
diff --git a/companion/src/firmwares/edgetx/yaml_rawsource.cpp b/companion/src/firmwares/edgetx/yaml_rawsource.cpp
index 868ab4776..df72ec4fd 100644
--- a/companion/src/firmwares/edgetx/yaml_rawsource.cpp
+++ b/companion/src/firmwares/edgetx/yaml_rawsource.cpp
@@ -45,9 +45,13 @@ const YamlLookupTable specialSourceLut = {
   {  0, "TX_VOLTAGE" },
   {  1, "TX_TIME"  },
   {  2, "TX_GPS"  },
-  {  3, "TIMER1"  },
-  {  4, "TIMER2"  },
-  {  5, "TIMER3"  },
+  {  3, "RESERVED1"  },
+  {  4, "RESERVED2"  },
+  {  5, "RESERVED3"  },
+  {  6, "RESERVED4"  },
+  {  7, "TIMER1"  },
+  {  8, "TIMER2"  },
+  {  9, "TIMER3"  },
 };
 
 std::string YamlRawSourceEncode(const RawSource& rhs)
diff --git a/companion/src/firmwares/opentx/opentxeeprom.cpp b/companion/src/firmwares/opentx/opentxeeprom.cpp
index 51402e931..d07c0887c 100644
--- a/companion/src/firmwares/opentx/opentxeeprom.cpp
+++ b/companion/src/firmwares/opentx/opentxeeprom.cpp
@@ -184,6 +184,7 @@ inline int MAX_MOUSE_ANALOG_SOURCES(Board::Type board, int version)
 #define NUM_PPM_INPUTS(board, version)        16
 #define ROTENC_COUNT(board, version)          ((IS_STM32(board) && version >= 218) ? 0 : 1)
 #define MAX_AUX_TRIMS(board)                  ((IS_FAMILY_HORUS_OR_T16(board) && !IS_FLYSKY_NV14(board)) ? 2 : 0)
+#define MAX_SOURCE_TYPE_SPECIAL(board, version)    SOURCE_TYPE_SPECIAL_COUNT
 
 inline int switchIndex(int i, Board::Type board, unsigned int version)
 {
@@ -382,13 +383,8 @@ class SourcesConversionTable: public ConversionTable {
       if (!(flags & FLAG_NOTELEMETRY)) {
         for (int i=0; i<MAX_GVARS(board, version); i++)
           addConversion(RawSource(SOURCE_TYPE_GVAR, i), val++);
-        addConversion(RawSource(SOURCE_TYPE_SPECIAL, 0), val++); // BATT
-        addConversion(RawSource(SOURCE_TYPE_SPECIAL, 1), val++); // TIME
-        addConversion(RawSource(SOURCE_TYPE_SPECIAL, 2), val++); // GPS
-        val += 4;
-        addConversion(RawSource(SOURCE_TYPE_SPECIAL, 3), val++); // Timer1
-        addConversion(RawSource(SOURCE_TYPE_SPECIAL, 4), val++); // Timer2
-        addConversion(RawSource(SOURCE_TYPE_SPECIAL, 5), val++); // Timer3
+        for (int i=0; i<MAX_SOURCE_TYPE_SPECIAL(board, version); i++)
+          addConversion(RawSource(SOURCE_TYPE_SPECIAL, i), val++);
         for (int i=0; i<MAX_TELEMETRY_SENSORS(board, version)*3; ++i) {
           addConversion(RawSource(SOURCE_TYPE_TELEMETRY, i), val++);
         }
diff --git a/companion/src/firmwares/rawsource.cpp b/companion/src/firmwares/rawsource.cpp
index d0cc4b5ee..36844fab0 100644
--- a/companion/src/firmwares/rawsource.cpp
+++ b/companion/src/firmwares/rawsource.cpp
@@ -141,7 +141,7 @@ QString RawSource::toString(const ModelData * model, const GeneralSettings * con
   };
 
   static const QString special[] = {
-    tr("Batt"), tr("Time"), tr("GPS")
+    tr("Batt"), tr("Time"), tr("GPS"), tr("Reserved1"), tr("Reserved2"), tr("Reserved3"), tr("Reserved4")
   };
 
   static const QString rotary[]  = { tr("REa"), tr("REb") };
@@ -212,11 +212,11 @@ QString RawSource::toString(const ModelData * model, const GeneralSettings * con
         return LimitData().nameToString(index);
 
     case SOURCE_TYPE_SPECIAL:
-      if (index >= SOURCE_TYPE_SPECIAL_TIMER1_IDX && index <= SOURCE_TYPE_SPECIAL_TIMER1_IDX + CPN_MAX_TIMERS - 1) {
+      if (index >= SOURCE_TYPE_SPECIAL_FIRST_TIMER && index <= SOURCE_TYPE_SPECIAL_LAST_TIMER) {
         if (model)
-          result = model->timers[index - SOURCE_TYPE_SPECIAL_TIMER1_IDX].nameToString(index - SOURCE_TYPE_SPECIAL_TIMER1_IDX);
+          result = model->timers[index - SOURCE_TYPE_SPECIAL_FIRST_TIMER].nameToString(index - SOURCE_TYPE_SPECIAL_FIRST_TIMER);
         else
-          result = TimerData().nameToString(index - SOURCE_TYPE_SPECIAL_TIMER1_IDX);
+          result = TimerData().nameToString(index - SOURCE_TYPE_SPECIAL_FIRST_TIMER);
       }
       else
         result = CHECK_IN_ARRAY(special, index);
@@ -293,7 +293,7 @@ bool RawSource::isSlider(int * sliderIndex, Board::Type board) const
 
 bool RawSource::isTimeBased(Board::Type board) const
 {
-  return (type == SOURCE_TYPE_SPECIAL && index >= SOURCE_TYPE_SPECIAL_TIMER1_IDX);
+  return (type == SOURCE_TYPE_SPECIAL && index >= SOURCE_TYPE_SPECIAL_FIRST_TIMER && index <= SOURCE_TYPE_SPECIAL_LAST_TIMER);
 }
 
 bool RawSource::isAvailable(const ModelData * const model, const GeneralSettings * const gs, Board::Type board) const
@@ -309,6 +309,9 @@ bool RawSource::isAvailable(const ModelData * const model, const GeneralSettings
   if (type == SOURCE_TYPE_SWITCH && index >= b.getCapability(Board::Switches))
     return false;
 
+  if (type == SOURCE_TYPE_SPECIAL && index >= SOURCE_TYPE_SPECIAL_FIRST_RESERVED && index <= SOURCE_TYPE_SPECIAL_LAST_RESERVED)
+    return false;
+
   if (model) {
     if (type == SOURCE_TYPE_VIRTUAL_INPUT && !model->isInputValid(index))
       return false;
diff --git a/companion/src/firmwares/rawsource.h b/companion/src/firmwares/rawsource.h
index 25779ccd4..f5fbfbcd5 100644
--- a/companion/src/firmwares/rawsource.h
+++ b/companion/src/firmwares/rawsource.h
@@ -178,8 +178,25 @@ enum RawSourceType {
   MAX_SOURCE_TYPE
 };
 
+enum RawSourceTypeSpecial {
+  SOURCE_TYPE_SPECIAL_TX_BATT,
+  SOURCE_TYPE_SPECIAL_TX_TIME,
+  SOURCE_TYPE_SPECIAL_TX_GPS,
+  SOURCE_TYPE_SPECIAL_FIRST_RESERVED,
+  SOURCE_TYPE_SPECIAL_RESERVED1 = SOURCE_TYPE_SPECIAL_FIRST_RESERVED,
+  SOURCE_TYPE_SPECIAL_RESERVED2,
+  SOURCE_TYPE_SPECIAL_RESERVED3,
+  SOURCE_TYPE_SPECIAL_RESERVED4,
+  SOURCE_TYPE_SPECIAL_LAST_RESERVED = SOURCE_TYPE_SPECIAL_RESERVED4,
+  SOURCE_TYPE_SPECIAL_FIRST_TIMER,
+  SOURCE_TYPE_SPECIAL_TIMER1 = SOURCE_TYPE_SPECIAL_FIRST_TIMER,
+  SOURCE_TYPE_SPECIAL_TIMER2,
+  SOURCE_TYPE_SPECIAL_TIMER3,
+  SOURCE_TYPE_SPECIAL_LAST_TIMER = SOURCE_TYPE_SPECIAL_TIMER3,
+  SOURCE_TYPE_SPECIAL_COUNT
+};
+
 constexpr int SOURCE_TYPE_STICK_THR_IDX { 3 };      //  TODO is there a function to determine index?
-constexpr int SOURCE_TYPE_SPECIAL_TIMER1_IDX { 3 }; //  TODO temp const until Timers own source type
 
 class RawSourceRange
 {